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Assessment of Physicochemical Properties and Comparative Pollution Status of the Dhaleshwari River in Bangladesh

Assessment of Physicochemical Properties and Comparative Pollution Status of the Dhaleshwari... Article Assessment of Physicochemical Properties and Comparative Pollution Status of the Dhaleshwari River in Bangladesh 1 2 1 , Md. Al Sadikul Islam , Mohammad Enayet Hossain and Nehreen Majed * Department of Civil Engineering, University of Asia Pacific, Dhaka 1205, Bangladesh; sadikul96@outlook.com Department of Soil, Water and Environment, Dhaka University, Dhaka 1000, Bangladesh; enayetswe@du.ac.bd * Correspondence: nehreen-ce@uap-bd.edu; Tel.: +88-01819206394 Abstract: The Dhaleshwari river which flows near Dhaka, the capital of Bangladesh, is currently under threat due to the recent relocation of the Hazaribagh tannery to the Savar area. This study investigated the physicochemical parameters of water quality along with the heavy metal levels in the Dhaleshwari river and performed a comparative analysis among the peripheral rivers around Dhaka City. Surface water quality parameters such as total dissolved solids (TDS), biochemical oxygen demand (BOD ), and chemical oxygen demand (COD) obtained for the Dhaleshwari river deviated by as much as 90% from World Health Organization (WHO) standards in certain instances due to direct discharge from untreated point sources. Concentrations of toxic metals such as chromium (Cr), cadmium (Cd), and nickel (Ni) were above the Food and Agriculture Organization (FAO) standards for heavy metals in surface waters. Strong correlations among the heavy metals indicated significant linear dependences. Based on the physicochemical and toxicity-based characterization, the river system in Dhaka city can be termed as severely polluted with respect to organic and solids discharge, while ecological risk indices (E ) indicated disastrously high risk in the Dhaleshwari and Buriganga RI Citation: Islam, M.A.S.; Hossain, rivers. The study outcomes emphasize the necessity of frequent investigation while controlling the M.E.; Majed, N. Assessment of point and nonpoint urban pollution sources discharging into the peripheral rivers of Dhaka city. Physicochemical Properties and Comparative Pollution Status of the Keywords: river water; pollution; Dhaleshwari; heavy metals; wastewater; ecological risk Dhaleshwari River in Bangladesh. Earth 2021, 2, 696–714. https:// doi.org/10.3390/earth2040041 1. Introduction Academic Editor: Laura Bulgariu Life and health depend on freshwater, which is a vital issue to public health and welfare. Almost all civilizations on Earth are inextricably linked by rivers, which are Received: 9 August 2021 the places where they originated and evolved from. Once, the rivers of Bangladesh Accepted: 26 September 2021 Published: 30 September 2021 were its lifeblood, but pollution is now a major national problem, mainly owing to the ever-increasing development activities surrounding riverbank areas that lack appropriate Publisher’s Note: MDPI stays neutral environmental protection [1,2]. Such rivers are vast reservoirs for numerous fish and with regard to jurisdictional claims in different aquatic species [3]. The river water is utilized inconceivably for maintaining the published maps and institutional affil- water system, energy generation, navigation, amusement, and numerous industrial and iations. domestic purposes [4]. Changes in the quality of inland surface water are typically caused by industrial operations and seasonal variations in river flow [5]. Rapid and unplanned urban sprawl, industrial growth, and population pressure have made the city an environmentally polluted area [6,7]. The waterways of Bangladesh have become more polluted due to the excessive Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. usage of pesticides in the surrounding river lands, unrestricted urbanization, lack of well- This article is an open access article planned construction along riverbanks, and population expansion. In Bangladesh, surface distributed under the terms and water is used for drinking purposes, farming, and fishing [8,9]. Mills and industries are conditions of the Creative Commons dumping chemical and hazardous wastes into numerous rivers posing health risks to Attribution (CC BY) license (https:// people. Since the dawn of society and progress, threats continue to exist side by side creativecommons.org/licenses/by/ with development initiatives. As a young delta, the river channels are constantly shifting. 4.0/). Earth 2021, 2, 696–714. https://doi.org/10.3390/earth2040041 https://www.mdpi.com/journal/earth Earth 2021, 2 697 The peripheral rivers of Dhaka city are vulnerable to natural calamities, climate-change- related problems, transboundary challenges, and, last but not the least, anthropogenic interventions [10]. In recent years, water quality issues have emerged with concerns surrounding water flow and, subsequently, the water bodies’ carrying capacity. In central Dhaka, the Dhaleshwari River is one of the main distributaries on the left bank of the Jamuna River, which has a length of 160 km and has an average depth of around 37 m [11,12]. In its surrounding territories, this river makes a significant contribution to socio-economic development [13]. The Dhaleshwari receives substantial amounts of munic- ipal waste, surface runoff, unregulated industrial waste, and directly or indirectly treated sewage waste from Saver City [14]. These contaminants pollute the river water making it unsuitable for use and harming aquatic lifeforms. Most notably, the physicochemical quality of the river has deteriorated, and most of the water quality parameters do not meet the minimum standard guidelines for safe drinking water by World Health Organization (WHO). Contaminated water intake may be associated with several illnesses such as can- cer, congenital abnormalities, central nervous system problems, and endocrine system disturbance and heart disease. Blue baby diseases, gastric cancer, and other disorders are also associated with nitrate and nitrite-contaminated water diseases [15–17]. Biological diversity as well as other aquatic communities, including fish, are declining, putting the rivers of Dhaka, such as Dhaleshwari, at risk of becoming “dead” river in the coming days. The government of Bangladesh relocated the tannery industries from their previous site in Hazaribagh beside the Buriganga river, to a new location in Savar due to the dangerous impact that the tannery wastes were posing for human and environmental health in Hazaribagh. Modernization of the tanneries and treatment of effluents in a contemporary central effluent treatment plant (CETP) have been the primary goals of this move, which would result in a waste management system for the tannery industry that is more environmentally sound. However, as claimed by tannery industrial park residents, the water quality of the Dhaleshwari river has worsened, and this has been published in several local newspapers. Improper release of waste into the waterway, circumventing the mainline of the CETP, was the subject of several frightening media reports. CETP effluent released from the tannery industrial park has not been characterized in detail for its influence on the water quality of the surrounding river stretch. This warrants thorough investigation and characterization of water quality in the vicinity of the tannery. On another alarming note, heavy metals contamination in the aquatic ecosystem has drawn global attention in recent years because of the persistent nature, abundance, and prevalence of the same [18–20]. The rapid expansion of the world population, household activities, agricultural and industrial output have resulted in the release of large quantities of toxics such as heavy metals into rivers across the world [21–23]. Severe contamination of water, soil, and atmosphere are observed with unprecedented accumulation and dispersion of heavy metals, affecting marine and aquatic species [24–27]. Rivers constitute predominant pathways for the transport of heavy metals [28,29], and several poisonous metals eventually become part of numerous riverine frameworks [30] due to absorption, precipitation, solubility, and complexity processes [30–32], affecting their actions and bioavailability [31,32]. Due to the practice of dumping untreated commercial and residential trash into water bodies, metal concentrations are increasing in river water [33,34]. The nature of metals in natural water is dependent on the composition of the water substrate, suspended sedi- ment, and the quality of the water [35]. The Association of metals in sediments of various geological stages has a significant impact on the cumulative behavior of heavy metals in aquatic environments [36]. In predicting potential pollution, flexibility, and bioavailability, geochemical speciation and metal distribution in the given chemical fractions are generally used [36–39]. River water polluted with heavy metals such as cadmium (Cd), chromium (Cr), zinc (Zn), and nickel (Ni) can damage crops such as vegetables and rice [40–44]. The assessment of the contamination by and transmission of heavy metals in the riverine environment is therefore essential. Heavy metals in the concerned peripheral rivers around Dhaka city may be a result of human activities, such as mining and the disposal of improp- Earth 2021, 2, FOR PEER REVIEW 3 erally used [36–39]. River water polluted with heavy metals such as cadmium (Cd), chro- mium (Cr), zinc (Zn), and nickel (Ni) can damage crops such as vegetables and rice [40– 44]. The assessment of the contamination by and transmission of heavy metals in the riv- erine environment is therefore essential. Heavy metals in the concerned peripheral rivers around Dhaka city may be a result of human activities, such as mining and the disposal of improperly handled or untreated effluent from industries such as tanneries, battery Earth 2021, 2 698 industries, steel plants, and thermal power plants, as well as pesticides used in agricul- tural fields and compost containing heavy metals [45]. The Aim of the Study erly handled or untreated effluent from industries such as tanneries, battery industries, steel plants, and thermal power plants, as well as pesticides used in agricultural fields and In the context of the facts discussed above, the present study aims to evaluate the compost containing heavy metals [45]. pollution condition of the Dhaleshwari river due to the impact of the newly shifted tan- nery industrial park as compared to the Buriganga river in general. This study also makes The Aim of the Study a comparative assessment of the surface water quality among all the peripheral rivers In the context of the facts discussed above, the present study aims to evaluate the pollution around Dh condition aka City of the that h Dhaleshwari as rarely river been due accomp to the impact lished of with re the newly spect shifted to bot tannery h physicochem- industrial park as compared to the Buriganga river in general. This study also makes a ical status of water quality and heavy metal contamination. A particular focus of this comparative assessment of the surface water quality among all the peripheral rivers around study consists of evaluating the ecological threat emanating from the presence of heavy Dhaka City that has rarely been accomplished with respect to both physicochemical status metals in the surface water of the Dhaleshwari River which would further pave and ne- of water quality and heavy metal contamination. A particular focus of this study consists cessitate the ways towards mitigating the pollution and rehabilitating the river. of evaluating the ecological threat emanating from the presence of heavy metals in the surface water of the Dhaleshwari River which would further pave and necessitate the ways 2. Materials and Methods towards mitigating the pollution and rehabilitating the river. 2.1. Description of the Study Area and River Water Sampling 2. Materials and Methods 2.1. Description of the Study Area and River Water Sampling The peripheral river system of Dhaka city mainly consists of three different systems; Dhaleswari-Kaliganga System, Bangsi-Turag-Buriganga-Dhaleshwari System, and Balu- The peripheral river system of Dhaka city mainly consists of three different systems; Dhaleswari-Kaliganga System, Bangsi-Turag-Buriganga-Dhaleshwari System, and Balu- Lakhya System (Figure 1). The Dhaleswari-Kaliganga and Bangshi-Turag-Buriganga river Lakhya System (Figure 1). The Dhaleswari-Kaliganga and Bangshi-Turag-Buriganga river systems are to the west, and the Balu-Lakhya river system is to the east of Dhaka. The systems are to the west, and the Balu-Lakhya river system is to the east of Dhaka. The Dhaleshwari River originates from the Jamuna River near the north-western edge of Tan- Dhaleshwari River originates from the Jamuna River near the north-western edge of Tangail gail district and eventually reaches the Shitalakshya river near the district of Narayanganj. district and eventually reaches the Shitalakshya river near the district of Narayanganj. This This merged flow goes towards the south to combine with the Meghna River [46]. All the merged flow goes towards the south to combine with the Meghna River [46]. All the samples samplefor s fo the r th present e present investigation investigation were collected were frcol omlected selected from locations selected where lo the cation river s where the flows through the Savar District industrialized area. river flows through the Savar District industrialized area. Figure 1. GIS Map of the Sampling Stations along Dhaleshwari River. Figure 1. GIS Map of the Sampling Stations along Dhaleshwari River. Identified sampling stations were selected based on the intensity of industrialized Identified sampling stations were selected based on the intensity of industrialized zones and presence of waste disposal points beside the banks of the rivers. In the present zones and presence of waste disposal points beside the banks of the rivers. In the present study, five of the following places along the river were chosen: Savar Tannery (D-1), study, five of the following places along the river were chosen: Savar Tannery (D-1), Sudkhira (D-2), Dhalla (fish market) (D-3), AKS dying (D-4), and Nama Bazar (D-5) at Sudkhira (D-2), Dhalla (fish market) (D-3), AKS dying (D-4), and Nama Bazar (D-5) at Savar district in Bangladesh (Figure 1). Global positioning system (GPS) coordinates were used to precisely locate each sampling station. The identification of the sampling stations and distances from the Savar Tannery are provided in Table 1. Earth 2021, 2, FOR PEER REVIEW 4 Savar district in Bangladesh (Figure 1). Global positioning system (GPS) coordinates were used to precisely locate each sampling station. The identification of the sampling stations and distances from the Savar Tannery are provided in Table 1. Earth 2021, 2 699 Table 1. Identification of sampling stations and distance from D-1 in Dhaleshwari River. Sampling Stations Type of Discharge Distance from Savar Tannery (km) Table 1. Identification of sampling stations and distance from D-1 in Dhaleshwari River. D-1 Industrial 0 D-2 Municipal 1.7 Distance from Savar Tannery Sampling Stations Type of Discharge D-3 Industrial 3.7 (km) D-4 Industrial 4.1 D-1 Industrial 0 D-5 Industrial 6.2 D-2 Municipal 1.7 D-3 Industrial 3.7 D-4 Industrial 4.1 The peripheral rivers around Dhaka City are depicted in Figure 2, with the red boxes D-5 Industrial 6.2 showing the sampling locations. A minimum average of three samples was collected from each of the Turag, Tongi Canal, Balu, Buriganga, and Shitalakhya rivers. The sampling The peripheral rivers around Dhaka City are depicted in Figure 2, with the red boxes stations were chosen along the zones of concentrated levels of industrial and agricultural showing the sampling locations. A minimum average of three samples was collected from activities with numerous point sources and non-point sources of contamination. Different each of the Turag, Tongi Canal, Balu, Buriganga, and Shitalakhya rivers. The sampling indu stations strial wer sec e chosen tors such along as the lea zones therof , tex concentrated tiles, and levels metal of industrial processing andcon agricultu stitute ral the point activities with numerous point sources and non-point sources of contamination. Different sources. Other industries considered as point sources include power plants, fertilizer and industrial sectors such as leather, textiles, and metal processing constitute the point sources. pharmaceutical plants, and industries that dye fabrics and produce batteries or ink, as Other industries considered as point sources include power plants, fertilizer and pharma- well as metal melting plants. In addition, waste disposal points, toxic sewage, terminals, ceutical plants, and industries that dye fabrics and produce batteries or ink, as well as metal and landing stations also constitute point sources and contribute to pollution. Twenty melting plants. In addition, waste disposal points, toxic sewage, terminals, and landing samples in total were collected from all the rivers for physicochemical analysis, and five stations also constitute point sources and contribute to pollution. Twenty samples in total add wer itiona e collected l sam fr ples om all were the rivers obtaifor ned physi from cochemical Dhaleshwa analysis, ri River and five for additional heavy met samples al analysis. Un- were obtained from Dhaleshwari River for heavy metal analysis. Unfiltered samples of filtered samples of water were obtained from the middle of the river course. The samples water were obtained from the middle of the river course. The samples were then placed were then placed into 100 mL polypropylene bottles, and then the bottles were sealed. In into 100 mL polypropylene bottles, and then the bottles were sealed. In each polypropylene each polypropylene bottle, 1 mL of ultrapure nitric acid was added to achieve a pH of ~1 bottle, 1 mL of ultrapure nitric acid was added to achieve a pH of ~1 [47] before transferring [47] before transferring to the Department of Soil, Water and Environment Laboratory of to the Department of Soil, Water and Environment Laboratory of the University of Dhaka the University of Dhaka for heavy metals analysis. The standard sampling procedure was for heavy metals analysis. The standard sampling procedure was followed to collect all samples at every single sampling station [48–52]. followed to collect all samples at every single sampling station [48–52]. Figure 2. GIS Map Showing Peripheral Rivers around Dhaka city (boxes representing the sampling Figure 2. GIS Map Showing Peripheral Rivers around Dhaka city (boxes representing the sam- stretches along the rivers). pling stretches along the rivers). 2.2. Analysis of Physicochemical Parameters and Heavy Metals for Water Samples Water samples collected from all the rivers were analyzed for the physicochemical parameters in the Environmental Engineering Laboratory, Department of Civil Engineering, Earth 2021, 2 700 University of Asia Pacific. Standard instruments were used to test the conductivity, total dissolved solids (TDS), pH, and dissolved oxygen (DO). Electrical conductivity (EC) and total suspended solids (TSS) were assessed by a model ‘CTS-406 meter manufactured by EZDO (Taipei City, Taiwan); pH was determined by a B-221 pH meter (Twin, Santee, USA), and DO was assessed by a model ’YK-22DO’ dissolved oxygen meter (EZDO, Taipei City, Taiwan). Chemical oxygen demand (COD) was determined by using condensation and oxi- dation with potassium dichromate. All the heavy metals such as cadmium (Cd), chromium (Cr), nickel (Ni), and zinc (Zn) were analyzed in the Department of Soil, Water, and En- vironment at the University of Dhaka. The toxic metal concentrations were calculated by an “AA-7000’ atomic absorption spectrometer manufactured by Shimadzu (South San Francisco, USA). For all measurements an accurate ‘ABS 220-4’ precision electrical balance manufactured by KERN (Ziegelei, Balingen, Germany) was used. Preconcentrated samples were filtered using a nylon membrane filter (47 mm diameter, Whatman, Washington, DC, USA) to determine hazardous metals concentration [53]. For heavy metal analysis, 100 mL of each sample was collected and placed in a Pyrex volumetric flask. 1 M HCl (9 mL) and 1 M HNO (3 mL) were added next. The volumetric flask was carefully heated in a sand bath placed in a fume hood to reduce the moisture level. Deionized water was added to the sample after the flask was cooled to room temperature. The filtrate was collected in a 250 mL high density polyethylene screw-cap (HDPE) plastic container tube with a polypropylene/low density polyethylene (LDPE)-lined cap; Thermo Scientific, Washington, DC, USA). Finally samples were retained for the calculation of the concentration of the metals. The atomic absorption spectrometer (AAS) was calibrated for all the metals by running different standard concentrations. Three observations of each data point were averaged. In this case, the detection limit was set at 0.001 mg/L. An oven (GAF-7000, ESCO, Changi South Street, Singapore) was used to test the amounts of the metals present. 2.3. Multivariate Statistical Analysis Pearson’s correlation and linear regression analysis was performed to evaluate the relationship between the metals to validate the multivariate analysis (SPSS v.25, Armonk, NY, USA). The map showing the locations of the Dhaleshwari River sampling stations was generated using ArcGIS 10.3 (Esri Bangladesh, Dhaka, Bangladesh). 2.4. Assessment of Ecological Risk Hakanson [54] suggested the possible ecological risk index approach from a sedimen- tology aspect first to determine the natural and environmental behavior of heavy metal pollutants. A single coefficient of pollution, an indicator of a heavy metal toxic reaction, an exact measure of pollution, and a possible ecological risk index are included in the process. Ecological risk index (E ) was obtained by following equations [54]: RI i i i i E = T (C /C ) r r o E = E RI å r i i where C and C are the concentrations of particular heavy metals and their permitted i i reference value, respectively, and E represents an ecological risk factor. T is the toxicity r r factor for each metal (Cd = 30, Cr = 2, Ni = 5, and Zn = 1) [53]. E represents the ecological RI risk that determines how sensitive biological populations to particular metals are in the area being considered. Table 2 shows the ranges of the indices of E and E based on r RI which the categorization of risk was evaluated for the rivers. Higher values of E and E RI indicate higher risks for the ecosystem. Wastewater does not have a standard value for assessing ecological risks. Thus, classification of ecological risk exposed to toxic metals was consulted, which is provided below: Earth 2021, 2 701 Table 2. Classification of ecological risk index (E ) of heavy metal pollution [55,56]. RI E Classification r RI E < 30 E < 100 Low risk r RI 30  E < 50, 100  E < 150 Moderate risk r RI 150  E < 200 Considerable risk 50  E < 100 r RI 100  E < 150 200  E < 300 Very high risk r RI E  150 E  300 Disastrous risk r RI 3. Results and Discussion 3.1. Assessment of Physicochemical Parameters of Surface Water Surface water sampled from all the rivers in Dhaka City were analyzed for various water quality indicators. Table 3 summarizes the results on the assessment of physico- chemical characterization of the peripheral rivers around Dhaka City along with the water quality guidelines established by the WHO and Environmental Conservation Rule (ECR). Average values of all the parameters that were obtained from sampling at multiple locations have been presented in Table 3 that provides a comparative scenario in a snapshot. The Dhaleshwari River water was dark in color and had an acrid odor during the period of the study. The pH value varied from 6.9 to 11.2, along with the sampling locations of the river. The maximum pH value was observed at Sampling station D-1 (Savar Tannery), and the minimum pH value was recorded at Sampling station D-3 (Dhalla, fish market). Table 3. Results of Physicochemical properties of the peripheral rivers around Dhaka City. Average  Standard Error of Mean WHO Parameter Unit ECR’97 Dhaleshwar Buriganga Shitalakshya (2011) Turag River Tongi Canal Balu River River River River pH 6.5–8.5 6.5–8.5 8.04  0.14 6.7  0.17 6.66  0.15 7.23  0.14 6.9  0.06 7.1  0.06 TSS - 619.6  107.19 385  61.44 556.33  92.59 605  131.43 278.33  58.9 368.33  80.84 TDS mg/L 1000 1364.6  321.35 235  2.88 475  2.88 46.66  2.33 241.66  6 930  138. 68 BOD mg/L >6 5 26.44  7.61 41.33  4.97 33.33  3.48 41.33  4.63 24.66  6.88 34.5  3.67 COD mg/L 10 461.74  110.36 675.33  371.62 247.86  35.14 602.76  145.92 250.56  40.78 351.4  28.87 DO mg/L >5 4–6 2.052  0.97 0.9  0.17 3.96  0.29 2.56  0.37 2.2  0.51 2.13  0.52 EC S/cm 1000 1709.34  204.07 987.33  68.71 1283.33  92.79 655  400 620.67  342.13 710  355.01 a b The Environment Conservation Rules, 1997; World Health Organization, 2011. m m Figures 3 and 4 represent Max Vs Min concentrations of pH and TDS, respectively for the peripheral rivers of Dhaka, along with the WHO standards in dotted lines. The pH value was within the standard limit in the study, as assessed for the other peripheral rivers in Dhaka City. Total dissolved solids (TDS) primarily represents the different types of minerals, alkalis, some colloidal and dissolved solids in water, some acids, sulfates, metallic ions, etc., [52]. TDS in the water of the Dhaleshwari River ranged from 412 to 3278 mg/L with the maximum level of TDS obtained at sampling station D-1 (Savar Tannery) and the minimum level at sampling station D-5 (Nama Bazar) (Figure 4). Except for Savar tannery (D-1) and Sudkhira (D-2), all sampling stations exhibited values below the permitted level of WHO guidelines (1000 mg/L) for Dhaleshwari River. The water becomes more turbid and saltier when the TDS level exceeds the allowable limit of 1000 mg/L, which has a negative impact on aquatic life [57,58]. Consequently, it has an ultimate effect on the human, crop, and livestock. During the monsoon season, runoff water flow may cause some variance, but this volatility has impacted the irrigation system. Effluents from dyeing units might potentially be a contributing factor to the elevated TDS levels reported in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). Earth 2021, 2, FOR PEER REVIEW 7 Earth 2021, 2, FOR PEER REVIEW 7 in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration Earth 2021, 2 702 was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). (Figure 4). m m m m m m Figure Figure 3. 3. Max Max vs. vs. Min Min Concentrations Concentrations of pH of pH for the for t peripheral he peripher rivers al rive of Dhaka rs of Dh with aka wit WHOh WHO Figure 3. Max vs. Min Concentrations of pH for the peripheral rivers of Dhaka with WHO standar standards ds in in dotted dotte lines d li(6.5–8.5). nes (6.5–8.5). standards in dotted lines (6.5–8.5). m m m m Figure 4. Max m vs. Min m Concentration of TDS for the peripheral rivers of Dhaka with WHO Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO standards in dotted lines (1000 mg/L). standards in dotted lines (1000 mg/L). standards in dotted lines (1000 mg/L). m m Figures 5 and 6 represent Max vs. m Min Concentrations m of BOD and DO for all Figures 5 and 6 represent Maxm vs. Minm Concentrations of BOD 5 5 and DO for all the Figures 5 and 6 represent Max vs. Min Concentrations of BOD5 and DO for all the the peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of of BOD is the best single test for evaluating organic contamination and has significant BOD5 is the best single test for evaluating organic contamination and has significant rele- BOD5 is the best single test for evaluating organic contamination and has significant rele- relevance in water quality evaluation [60]. The BOD ranged from 11 to 45 mg/L for the vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). The observed BOD levels in the water samples indicated organic waste in the Dhaleshwari Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). river [61]. Among the sampling stations, the highest BOD was found at Sampling station The observed BOD5 levels in the water samples indicated organic waste in the The observed BOD5 levels in the water samples indicated organic waste in the D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sampling station Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD limits are 0.2 mg/L for pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irrigation [62]. pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are Since the sampling stations run through the most heavily populated and industrialized 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- region along the riverbank, the BOD was greater along the selected stretch in Dhaleshwari gation [62]. Since the sampling stations run through the most heavily populated and in- than it was along the other stretches. gation [62]. Since the sampling stations run through the most heavily populated and in- Organic materials are also discharged along with the effluent as a result of poor- dustrialized region along the riverbank, the BOD5 was greater along the selected stretch dustrialized region along the riverbank, the BOD5 was greater along the selected stretch functioning of the sewage treatment plants, storm discharges, agricultural slurries, domes- in Dhaleshwari than it was along the other stretches. in Dhaleshwari than it was along the other stretches. tic waste (waste from humans and food) and industrial waste (food industries, tannery, and dyeing) and silage liquor, thereby the Dhaleshwari River can accumulate various organic and chemical pollutants. BOD levels varied within 33–49 mg/L for the Buriganga River, 30–39 mg/L for the Shitalakshya River, 32–49 mg/L for the Turag River, 27–39 mg/L for the Tongi Canal, and 15–38 mg/L for the Balu River (Figure 5). This reveals that the discharge of organic substances and subsequent pollution is commonly happening in general for all the peripheral rivers at comparable rates. m m m m Figure 5. Max vs. Min Concentration of BOD5 in the peripheral rivers of Dhaka with WHO Figure 5. Max vs. Min Concentration of BOD5 in the peripheral rivers of Dhaka with WHO standards (5 mg/L). standards (5 mg/L). Earth 2021, 2, FOR PEER REVIEW 7 in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). m m Figure 3. Max vs. Min Concentrations of pH for the peripheral rivers of Dhaka with WHO standards in dotted lines (6.5–8.5). m m Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO standards in dotted lines (1000 mg/L). m m Figures 5 and 6 represent Max vs. Min Concentrations of BOD5 and DO for all the peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of BOD5 is the best single test for evaluating organic contamination and has significant rele- vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). The observed BOD5 levels in the water samples indicated organic waste in the Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- gation [62]. Since the sampling stations run through the most heavily populated and in- Earth 2021, 2 703 dustrialized region along the riverbank, the BOD5 was greater along the selected stretch in Dhaleshwari than it was along the other stretches. Earth 2021, 2, FOR PEER REVIEW 8 m m m m Figure Figure 5.5. Max Max vs. vs. Min Min Concentration Concentration o of BOD f BO in Dthe 5 in peripheral the peripheral riversrive of Dhaka rs of Dh with aka wit WHOh WHO standar standards ds (5 mg/L). (5 mg/L). m m m m Figure Figure 6. 6 Max . Maxvs. vs. Min Min Concentration Concentration DO DO of peripheral of peripher rivers al of riv Dhaka ers of with Dhak WHO a with standar WHO stand ds ards (6 (6 m mg/L). g/L). The concentration of dissolved oxygen (DO) is a vital issue for aquatic organisms in Organic materials are also discharged along with the effluent as a result of poor-func- surface waters [8,63]. Low DO levels are indicative of the presence of oxygen-consuming tioning of the sewage treatment plants, storm discharges, agricultural slurries, domestic pollutants in the water body. The concentration of dissolved oxygen influences several waste (waste from humans and food) and industrial waste (food industries, tannery, and aspects of the water body (bacteria and photosynthesis), the availability and concentration dyeing) and silage liquor, thereby the Dhaleshwari River can accumulate various organic of nutrients [64]. The DO concentration among sampling stations along Dhaleshwari River ranged from 0.06 to 5.1 mg/L (Figure 6). The DO concentrations of all sampling stations and chemical pollutants. BOD5 levels varied within 33–49 mg/L for the Buriganga River, were deficient in the Dhaleshwari River. Sampling station D-1 exhibited the lowest value 30–39 mg/L for the Shitalakshya River, 32–49 mg/L for the Turag River, 27–39 mg/L for of DO (0.06 mg/L) beside the Savar tannery area. According to the Environmental Quality the Tongi Canal, and 15–38 mg/L for the Balu River (Figure 5). This reveals that the dis- Standard (EQS), the accompanying DO requirements are acceptable: fish and domesticated charge of organic substances and subsequent pollution is commonly happening in general animals require 4 to 6 milligrams per liter and 6 mg/L for drinking, 4 to 5 milligrams per for all the peripheral rivers at comparable rates. liter, whereas industrial applications require up to 5 milligrams per liter [50]. The The low con levels centra oftion dissolved of disso oxygen lved oxy could gen be(DO attributed ) is a vit to al the issue release forof aqu organic atic organisms in substances with high organic content, such as sewage treatment plants, storm flooding, surface waters [8,63]. Low DO levels are indicative of the presence of oxygen-consuming slurry cultivation, alcohol silage, etc. These low values of DO eventually impact the aquatic pollutants in the water body. The concentration of dissolved oxygen influences several species. By encouraging the growth of microorganisms in the water body, biodegradable aspects of the water body (bacteria and photosynthesis), the availability and concentration waste from industrial and residential sources causes a fast drop in DO value. All aquatic of nutrients [64]. The DO concentration among sampling stations along Dhaleshwari River species with aerobic respiratory biochemistry require oxygen to function [65]. When BOD ranged from 0.06 to 5.1 mg/L (Figure 6). The DO concentrations of all sampling stations levels are high, the amount of dissolved oxygen (DO) reduces because the bacteria absorb the were def oxygenicien obtained t in the Dh in the wate alershwar [65]. Consequ i River.ently Sampl , fish ing st and other ation D aquatic -1 exh species ibited t cannot he lowest value survive in oxygen-depleted conditions. Including the Dhaleshwari River as stated above, all of DO (0.06 mg/L) beside the Savar tannery area. According to the Environmental Quality the peripheral rivers of Dhaka were witnessed to have very low levels of dissolved oxygen, Standard (EQS), the accompanying DO requirements are acceptable: fish and domesti- ranging from 1.9–3.2 mg/L for the Buriganga River, 1.1–2.8 mg/L for the Shitalakshya River, cated animals require 4 to 6 milligrams per liter and 6 mg/L for drinking, 4 to 5 milligrams 0.6–1.2 mg/L for the Turag River, 3.4–4.4 mg/L for the Tongi Canal and 1.5–3.2 mg/L for per liter, whereas industrial applications require up to 5 milligrams per liter [50]. the Balu River (Figure 6). Almost all these ranges fall outside the required DO levels based The low levels of dissolved oxygen could be attributed to the release of organic sub- stances with high organic content, such as sewage treatment plants, storm flooding, slurry cultivation, alcohol silage, etc. These low values of DO eventually impact the aquatic spe- cies. By encouraging the growth of microorganisms in the water body, biodegradable waste from industrial and residential sources causes a fast drop in DO value. All aquatic species with aerobic respiratory biochemistry require oxygen to function [65]. When BOD5 levels are high, the amount of dissolved oxygen (DO) reduces because the bacteria absorb the oxygen obtained in the water [65]. Consequently, fish and other aquatic species cannot survive in oxygen-depleted conditions. Including the Dhaleshwari River as stated above, all the peripheral rivers of Dhaka were witnessed to have very low levels of dissolved oxygen, ranging from 1.9–3.2 mg/L for the Buriganga River, 1.1–2.8 mg/L for the Shita- lakshya River, 0.6–1.2 mg/L for the Turag River, 3.4–4.4 mg/L for the Tongi Canal and 1.5– 3.2 mg/L for the Balu River (Figure 6). Almost all these ranges fall outside the required DO levels based on the WHO guidelines (4–6 mg/L) (Figure 6). Figures 7 and 8 represent m m Max vs. Min Concentrations of TSS and COD respectively, for the peripheral rivers of Dhaka. Earth 2021, 2 704 Earth 2021, 2, FOR PEER REVIEW 9 m m Earth 2021, 2, FOR PEER REVIEW 9 on the WHO guidelines (4–6 mg/L) (Figure 6). Figures 7 and 8 represent Max vs. Min Concentrations of TSS and COD respectively, for the peripheral rivers of Dhaka. m m m m Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. m m Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. m m Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO m m m m Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO standards (10 mg/L). standards (10 mg/L). standards (10 mg/L). Total Total suspended suspended solids solids (TSS) (Tvalues SS) values in the in Dhaleshwari the Dhaleshw River ari varied River var from ied 191 from to 191 to 1278 Total suspended solids (TSS) values in the Dhaleshwari River varied from 191 to 1278 1278 mg/L (Figure 7). In studies involving sewage and other wastewater, the determination mg/L (Figure 7). In studies involving sewage and other wastewater, the determination of mg/L (Figure 7). In studies involving sewage and other wastewater, the determination of of suspended solids is especially useful and is as critical as the determination of BOD [61]. suspended solids is especially useful and is as critical as the determination of BOD5 [61]. suspended solids is especially useful and is as critical as the determination of BOD5 [61]. The presence of suspended solids in the canal is undesirable for causing putrefaction, and The presence of suspended solids in the canal is undesirable for causing putrefaction, and The presence of suspended solids in the canal is undesirable for causing putrefaction, and suspended particles can also contain many organic materials. The concentration levels of suspended particles can also contain many organic materials. The concentration levels of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment suspended particles can also contain many organic materials. The concentration levels of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment industrial waste and sewage to contamination and the quantity of oxygen required to (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of oxidize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari industrial waste and sewage to contamination and the quantity of oxygen required to ox- industrial waste and sewage to contamination and the quantity of oxygen required to ox- varied between 121.2 and 935 mg/L (Figure 8). In sampling station D-1, the highest COD idize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari idize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari value was correlated with the flow of effluent from the dyeing unit that is released into varied between 121.2 and 935 mg/L (Figure 8). In sampling station D-1, the highest COD the vari river ed .bet The we higher en 12 levels 1.2 and of COD 935 mg/ in the L samples (Figure suggest 8). In sam an incr pling eased statio concentration n D-1, the of highest COD value was correlated with the flow of effluent from the dyeing unit that is released into industrial contaminants containing inorganic and organic compounds, thereby indicating value was correlated with the flow of effluent from the dyeing unit that is released into ath higher e river. degr Th eeeof higher toxicity leve [67,ls 68]. of COD COD values in thranged e samp frles om su 170–1400 ggest an mg/L incr for eathe sed Turag concentration of the river. The higher levels of COD in the samples suggest an increased concentration of River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, industrial contaminants containing inorganic and organic compounds, thereby indicating industrial contaminants containing inorganic and organic compounds, thereby indicating 180.2–321.49 mg/L for the Balu River, and 302.1–402.1 mg/L for the Shitalakshya River, a higher degree of toxicity [67,68]. COD values ranged from 170–1400 mg/L for the Turag a higher degree of toxicity [67,68]. COD values ranged from 170–1400 mg/L for the Turag suggesting a high level of contamination in these rivers based on the WHO guideline River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, (10 mg/L) (Figure 8). 180.2–321.49 mg/L for the Balu River, and 302.1–402.1 mg/L for the Shitalakshya River, m m 180.2 Figur –32e 1.49 9 repr mg/ esents L for Max the vs. Balu Min River Concentrations , and 302.1–of 402.1 EC for mg/ the L peripheral for the Shi rivers talakshya River, suggesting a high level of contamination in these rivers based on the WHO guideline (10 of Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) suggesting a high level of contamination in these rivers based on the WHO guideline (10 varied mg/L) fr( om Fig286.1 ure 8). to 5309.6 S/cm in the Dhaleshwari River (Figure 9). According to the mg/L) (Figure 8). m m WHO standards, a water body with an EC of more than 1000 mg/L is not suitable for Figure 9 represents Max vs. Min Concentrations of EC for the peripheral rivers of m m Figure 9 represents Max vs. Min Concentrations of EC for the peripheral rivers of the agricultural sector, domestic, bathing, industrial, or drinking purposes. Among the Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) var- Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) var- ied from 286.1 to 5309.6 μS/cm in the Dhaleshwari River (Figure 9). According to the WHO ied from 286.1 to 5309.6 μS/cm in the Dhaleshwari River (Figure 9). According to the WHO standards, a water body with an EC of more than 1000 mg/L is not suitable for the agri- standards, a water body with an EC of more than 1000 mg/L is not suitable for the agri- cultural sector, domestic, bathing, industrial, or drinking purposes. Among the five sam- cultural sector, domestic, bathing, industrial, or drinking purposes. Among the five sam- pling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 pling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 μS/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 μS/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 μS/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed μS/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed WHO guidelines (1000 μS/cm) for the permissible limit of EC. Emissions from tanneries WHO guidelines (1000 μS/cm) for the permissible limit of EC. Emissions from tanneries and metal plating industries might be responsible for the increase in electrical conductiv- and metal plating industries might be responsible for the increase in electrical conductiv- ity. Industries like textile and dyeing generate heavy metals as well. There may be some ity. Industries like textile and dyeing generate heavy metals as well. There may be some physiological effects of high EC levels on plants and some of the environmental species. physiological effects of high EC levels on plants and some of the environmental species. Earth 2021, 2 705 five sampling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 S/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 S/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed Earth 2021, 2, FOR PEER REVIEW 10 WHO guidelines (1000 S/cm) for the permissible limit of EC. Emissions from tanneries and metal plating industries might be responsible for the increase in electrical conductivity. Industries like textile and dyeing generate heavy metals as well. There may be some physiological effects of high EC levels on plants and some of the environmental species. However, these concentrations suggest that wastewater (industrial and sewage effluent) However, these concentrations suggest that wastewater (industrial and sewage effluent) containing high ionic concentrations get discharged into the rivers, ultimately causing containing high ionic concentrations get discharged into the rivers, ultimately causing detrimental effects to the aquatic biodiversity. With respect to the other peripheral rivers, detrimental effects to the aquatic biodiversity. With respect to the other peripheral rivers, EC varied from 890 to 1120 µ S/cm for the Turag River, 1100 to 1400 µ S/cm for the Tongi EC varied from 890 to 1120 S/cm for the Turag River, 1100 to 1400 S/cm for the Tongi Canal, 10 to 1390 µ S/cm for the Buriganga River, 220 to 1400 µ S/cm for the Shitalakhya Canal, 10 to 1390 S/cm for the Buriganga River, 220 to 1400 S/cm for the Shitalakhya River River , and , an210 d 21 to0 1300 to 1300 S/cm µ Sf /c or m the for Balu the River Balu . Based River. on Ba WHO sed on criteria, WHO these criteri rivers a, th have ese rivers have significant levels of ionic pollution (Figure 9). significant levels of ionic pollution (Figure 9). m m m m Figure 9. Max vs. Min Concentration of EC for the peripheral rivers of Dhaka for with WHO Figure 9. Max vs. Min Concentration of EC for the peripheral rivers of Dhaka for with WHO standar standard in d d in dotted otted line l(1000 ine (1000 S/cm). μS/cm). 3.2. Correlation among the Physicochemical Parameters of Dhaleshwari River 3.2. Correlation among the Physicochemical Parameters of Dhaleshwari River The correlation coefficient represents the relations among the variables and the assess- The correlation coefficient represents the relations among the variables and the as- ment of whether a specific variable depends on the other variables or not. Correlations among sessmen thet physicochemical of whether a spec parameters ific variof abl analyzed e depenwater ds on samples the other from variable the Dhaleshwari s or not. Correlations River were obtained using Pearson’s correlation and linear regression analysis in order among the physicochemical parameters of analyzed water samples from the Dhaleshwari to determine their interrelationships [61]. The correlation matrix among different water River were obtained using Pearson’s correlation and linear regression analysis in order to quality parameters of the Dhaleshwari River is presented in Table 4. The correlation coeffi- determine their interrelationships [61]. The correlation matrix among different water cient ranges between 1 and +1. Between 0.5 and 0.8, the relationship could be considered quality parameters of the Dhaleshwari River is presented in Table 4. The correlation coef- moderate, and above 0.8, the association could be considered substantial [69]. ficient ranges between −1 and +1. Between 0.5 and 0.8, the relationship could be consid- Table 4. Pearson’s correlation coefficients among the physicochemical parameters in the Dhaleshwari ered moderate, and above 0.8, the association could be considered substantial [69]. River (significance of correlation was measured both at 0.01 and 05 levels). Table 4. Pearson’s correlation coefficients among the physicochemical parameters in the Parameters pH TSS TDS BOD COD DO EC Dhaleshwari River (significance of correlation was measured both at 0.01 and 05 levels). pH 1 TSS 0.888 * 1 Parame- TDS 0.821 0.773 * 1 pH TSS TDS BOD5 COD DO EC ters BOD 0.550 0.590 0.547 1 COD 0.726 0.735 0.756 0.960 ** 1 pH 1 DO 0.517 0.796 0.452 0.783 0.766 1 TSS 0.888 * 1 EC 0.541 0.695 0.879 * 0.570 0.718 0.613 1 TDS 0.821 0.773 * 1 * Correlation is significant at the 0.05 level (2-tailed); ** Correlation is significant at the 0.01 level (2-tailed). BOD5 0.550 0.590 0.547 1 COD 0.726 0.735 0.756 0.960 ** 1 This investigation demonstrated that pH has significant strong positive correlations DO −0.517 −0.796 −0.452 −0.783 −0.766 1 (p < 0.01) with TSS and TDS (r = 0.888 and 0.821). It was also observed that DO has strong EC 0.541 0.695 0.879 * 0.570 0.718 −0.613 1 * Correlation is significant at the 0.05 level (2-tailed); ** Correlation is significant at the 0.01 level (2-tailed). This investigation demonstrated that pH has significant strong positive correlations (p < 0.01) with TSS and TDS (r = 0.888 and 0.821). It was also observed that DO has strong negative correlations with pH, TSS, TDS, BOD5, COD and EC (r = −0.517, −0.796, −0.452, −0.783, −0.766 and −0.613, respectively). The photosynthetic activity of algae, water tem- perature, aquatic respiration, oxidative degradation of organic materials, etc., impact pH and DO fluctuations [69]. It is also clear from the results that the TDS was moderately correlated with TSS, BOD5, COD, and EC (r = 0.773, 0.547, 0.756, 0.879 respectively) (Table 4). In water, this implies the presence of dissolved materials (organic matter and salts) Earth 2021, 2 706 negative correlations with pH, TSS, TDS, BOD , COD and EC (r = 0.517, 0.796, 0.452, 0.783, 0.766 and 0.613, respectively). The photosynthetic activity of algae, water temperature, aquatic respiration, oxidative degradation of organic materials, etc., impact pH and DO fluctuations [69]. It is also clear from the results that the TDS was moderately correlated with TSS, BOD , COD, and EC (r = 0.773, 0.547, 0.756, 0.879 respectively) (Table 4). In water, this implies the presence of dissolved materials (organic matter and salts) [70]. DO was shown to be negatively associated with all factors and not substantially connected with any of the examined parameters by Usharani et al. [61]. COD was found to have strong positive correlations (p < 0.01) with BOD (r = 0.960). EC was observed to possess significant positive correlation (p < 0.01) with pH, TSS, TDS, BOD , and COD respectively (r = 0.541, 0.695, 0.879, 0.570 and 0.718, respectively) and negatively correlated with DO (r = 0.613). It is also evident from these observations that the aquatic body is severely contaminated due to the different forms of industrial waste that are dumped directly into the water body. 3.3. Comparative Assessment of Heavy Metal Contamination Table 5 shows the concentrations of heavy metals in the Dhaleshwari River analyzed in the present study. This table also lists the heavy metal levels in the other peripheral rivers of Dhaka city that were reported by previous studies. Surface water standards by WHO and FAO are provided in the table as well. The average concentration levels of the analyzed heavy metals followed a decreasing order of Cr > Ni > Cd > Zn in the river water. The concentration of chromium in water varied from 0.08 to 0.92 mg/L in Dhaleshwari River, which might be due to the extensive disposal of domestic sewage and runoff from agricultural zone [22,24]. Table 5. Heavy Metals Concentration (mg/L) levels of the water samples of the Dhaleshwari River and the other peripheral rivers in Dhaka city. Average  Standard Error of Mean References Cd Cr Ni Zn Dhaleshwari River 0.19  0.01 0.71  0.16 0.62  0.1 0.18  0.03 Present Study Buriganga River 0.015  0.003 2.04  1.53 0.19  0.03 0.21  0.04 [70] Shitalakshya River 0.011  0.003 - - 0.0263  0.003 [71] Turag River - 0.32  0.02 0.018  0.003 0.10  0.01 [55] Tongi Canal - 0.01 0.005 0.156 [72] Balu River 0.01  0.001 - - 0.03  0.002 [71] WHO 0.003 0.05 0.05 3 [73] 0.01 0.1 0.2 2 [74] FAO a b WHO = World Health Organization; FAO = Food and Agriculture Organization. m m Figures 10 and 11 represent the Max vs Min Concentrations of the heavy metals Cd and Cr, respectively for all the peripheral rivers of Dhaka. The figures also show the WHO standards in dotted lines. The highest contamination of Cd was recorded at sampling location D-1 (0.25 mg/L), resulting from the Savar tannery industries zone, and the lowest amount was recorded at sampling location D-2 (Sudkhira) (0.15 mg/L) in the Dhaleshwari River (Figure 11). The results exceeded the allowable limits specified by World Health Organization (0.003 mg/L, Food and Agriculture Organization (0.01 mg/L), and The Environmental Conservation Rules (0.005 mg/L) [72–75]. Table 5 shows that Arefin et al. [55] recorded Cr at 0.32 mg/L in the Turag River, and Biswas et al. [72] found Cr at 0.01 mg/L in the Tongi Canal. The present study observed the highest chromium concentration at 7.76 mg/L in the Buriganga River [70] among the peripheral rivers (Figure 11), which may result from the operation and maintenance of various cooling towers at different industries beside Buriganga. Chromium-containing compounds from cooling towers might have been discharged into the Buriganga River. Although the selected section of the Dhaleswari river is located near the Savar tannery effluent discharge region, Earth 2021, 2 707 Earth 2021, 2, FOR PEER REVIEW 12 Earth 2021, 2, FOR PEER REVIEW 12 the concentration of Cr at this site is lower than that in Buriganga, however, exceeding the permissible level. Since water cotyledons (E. crassipes) were growing surrounding the sample site throughout the sampling period, these water cotyledons are believed to sample site throughout the sampling period, these water cotyledons are believed to accu- sample site throughout the sampling period, these water cotyledons are believed to accu- accumulate Cr and are termed chrome-sorbent plants [76,77]. mulate Cr and are termed chrome-sorbent plants [76,77]. mulate Cr and are termed chrome-sorbent plants [76,77]. Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted line line (0 (0.003 .003 mg/L). mg/L). line (0.003 mg/L). Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted line line (0.05 mg/L). line (0.05 mg/L). (0.05 mg/L). In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along the five sampling locations. Figure 10 shows that the concentration of Cd is above the the five sampling locations. Figure 10 shows that the concentration of Cd is above the the five sampling locations. Figure 10 shows that the concentration of Cd is above the tolerable limit specified by World Health Organization (WHO) and Food and Agricul- tolerable limit specified by World Health Organization (WHO) and Food and Agriculture tolerable limit specified by World Health Organization (WHO) and Food and Agriculture ture Organization (FAO) (0.003 mg/L and 0.01 mg/L, respectively) [73,74]. Potential Organization (FAO) (0.003 mg/L and 0.01 mg/L, respectively) [73,74]. Potential sources of sour Organ ces ization of cadmium (FAO in) the (0.00 Dhaleshwari 3 mg/L and River 0.01 m include g/L, r batteries, espectively pigment ) [73s, ,7and 4]. Poten plating tial sources of cadmium in the Dhaleshwari River include batteries, pigments, and plating businesses businesses [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may cadmium in the Dhaleshwari River include batteries, pigments, and plating businesses [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may be caused be caused by effluents from the Savar tannery industries, is higher than WHO allowable [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may be caused limit (0.05 mg/L). Apart from this, every sampling station around the industrial sector of by effluents from the Savar tannery industries, is higher than WHO allowable limit (0.05 by effluents from the Savar tannery industries, is higher than WHO allowable limit (0.05 Savar city has a Cr content over the permissible limit. Cadmium exposure for a prolonged mg/L). Apart from this, every sampling station around the industrial sector of Savar city mg/L). Apart from this, every sampling station around the industrial sector of Savar city period over the permissible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] has a Cr content over the permissible limit. Cadmium exposure for a prolonged period has a Cr content over the permissible limit. Cadmium exposure for a prolonged period reported that red tilapia mortality was caused in Alexandria, Egypt, through exposure to over the permissible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] reported very over high the levels permof iss cadmium. ible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] reported that red tilapia mortality was caused in Alexandria, Egypt, through exposure to very high Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for that red tilapia mortality was caused in Alexandria, Egypt, through exposure to very high water levels of ca samples dmium. for the Shitalakshya River by Mokaddes et al. [71] and 0.015 mg/L for levels of cadmium. the Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for current study was obtained at a much lower concentration than the water quality standard water samples for the Shitalakshya River by Mokaddes et al. [71] and 0.015 mg/L for the water samples for the Shitalakshya Ri m ver by m Mokaddes et al. [71] and 0.015 mg/L for the limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the cur- Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the cur- of Dhaka for Ni and Zn, respectively, while the WHO standards are shown in dotted lines. rent study was obtained at a much lower concentration than the water quality standard The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 rent study was obtained at a much lower concentration than the water quality standard m m limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers to 0.87 mg/L (Figure 12). Every sample location exceeded m Ni m concentrations according limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers to of WHO Dhaka permitted for Ni and limit Zn (0.1 , re mg/L). spectively, Nickel wis hil ae car thcinogenic e WHO stand metalar that ds leads are shown to sever in e dotted lines. of Dhaka for Ni and Zn, respectively, while the WHO standards are shown in dotted lines. The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 to The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 to 0.87 mg/L (Figure 12). Every sample location exceeded Ni concentrations according to 0.87 mg/L (Figure 12). Every sample location exceeded Ni concentrations according to WHO permitted limit (0.1 mg/L). Nickel is a carcinogenic metal that leads to severe dam- WHO permitted limit (0.1 mg/L). Nickel is a carcinogenic metal that leads to severe dam- age to the liver and heart, reduced body weight, and skin irritation due to long-term ex- age to the liver and heart, reduced body weight, and skin irritation due to long-term ex- posure [81]. posure [81]. Earth 2021, 2 708 Earth 2021, 2, FOR PEER REVIEW  13  Earth 2021, 2, FOR PEER REVIEW  13  damage to the liver and heart, reduced body weight, and skin irritation due to long-term exposure [81]. Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted line Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted  line (0.003 mg/L).  (0.003 mg/L). line (0.003 mg/L).  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted line (3 mg/L).  line (3 mg/L). line (3 mg/L).  Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in  Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in  the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag  the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag  River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas et  River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas et  et al. [72]. Several dockyards were established beside the Buriganga Riverbank, and a few al. [72]. Several dockyards were established beside the Buriganga Riverbank, and a few  launch al. [72] stations . Severar ale doc located kyanear rds were the station  estab [l 70 ished ]. Nickel  beside concentrations  the Buriga inng the a Riverb Buriganga ank, and a few  launch stations are located near the station [70]. Nickel concentrations in the Buriganga  River might result from several factors relating to discharge from specific manufacturing launch stations are located near the station [70]. Nickel concentrations in the Buriganga  industries. Ni has been associated with cancer, lung damage, and dermatitis, among other River might result from several factors relating to discharge from specific manufacturing  River might result from several factors relating to discharge from specific manufacturing  health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari industries. Ni has been associated with cancer, lung damage, and dermatitis, among other  industries. Ni has been associated with cancer, lung damage, and dermatitis, among other  River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO , health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari  health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari  which might explain why surface water has a lower percentage of Zn than deep water does, River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO3,  River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO3,  according to previous researchers [84]. The contamination of Zn was within the acceptable which might explain why surface water has a lower percentage of Zn than deep water  limit by WHO (3 mg/L) in all the peripheral rivers. which might explain why surface water has a lower percentage of Zn than deep water  does, according to previous researchers [84]. The contamination of Zn was within the ac‐ does, according to previous researchers [84]. The contamination of Zn was within the ac‐ 3.4. Correlation among the Heavy Metals in Dhaleshwari River ceptable limit by WHO (3 mg/L) in all the peripheral rivers.  ceptable limit by WHO (3 mg/L) in all the peripheral rivers.  The Pearson’s correlation matrix among the different trace metals for Dhaleshwari River is presented in Table 6. The majority of heavy metals showing a significantly linear 3.4. Correlation among the Heavy Metals in Dhaleshwari River  3.4. Correlation among the Heavy Metals in Dhaleshwari River  dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni The Pearson’s correlation matrix among the different trace metals for Dhaleshwari  and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719). The Pearson’s correlation matrix among the different trace metals for Dhaleshwari  River is presented in Table 6. The majority of heavy metals showing a significantly linear  This is because runoff from agricultural land, leather industries, and tanneries located in River is presented in Table 6. The majority of heavy metals showing a significantly linear  Savar city are constantly contributing untreated sewage and solid waste in the Dhaleshwari dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni  dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni  River, leading to an increased concentration of each of the metals. Tannery wastewater, and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719).  and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719).  including residues from the tanning, re-tanning, and basification phases of leather manu- This is because runoff from agricultural land, leather industries, and tanneries located in  This is because runoff from agricultural land, leather industries, and tanneries located in  facturing, as well as municipal sewerage, are included in this category. It is utilized to allow Savar  city  are  constantly  contributing  untreated  sewage  and  solid  waste  in  the  the Sav chr aromium   city  or are aldehyde   constato ntly attach   contributin to the sking pr  otein untrea during ted  the sew tanning age  an prd ocess   solid [84 ].waste  in  the  Dhaleshwari River, leading to an increased concentration of each of the metals. Tannery  Dhaleshwari River, leading to an increased concentration of each of the metals. Tannery  wastewater, including residues from the tanning, re‐tanning, and basification phases of  wastewater, including residues from the tanning, re‐tanning, and basification phases of  leather manufacturing, as well as municipal sewerage, are included in this category. It is  leather manufacturing, as well as municipal sewerage, are included in this category. It is  utilized to allow the chromium or aldehyde to attach to the skin protein during the tan‐ utilized to allow the chromium or aldehyde to attach to the skin protein during the tan‐ ning process [84].  ning process [84].          Earth 2021, 2 709 Table 6. Pearson’s Correlation matrix among the Heavy Metals in the Dhaleshwari River (significance of correlation was measured both at 0.05 levels). Parameters Cd Cr Ni Zn Cd 1 Cr 0.639 * 1 Ni 0.627 * 0.663 * 1 Zn 0.919 * 0.719 * 0.446 1 * Correlation is significant at the 0.05 level (2-tailed). 3.5. Ecological Risk Assessment A technique for assessing ecological hazards with relation to water pollution reduction was devised by Hakanson [54]. The ecological risk indices of individual metals for all the peripheral rivers have been estimated, which are presented in Table 7. The measured values of the ecological risk index (E ) for heavy metals show a descending trend along with the RI locations of Dhaleshwari River as follows: D-1 > D-4 > D-5> D-3> D-2. The calculated E RI values ranged from 469.71 to 830.32, with an average of 623.47 in Dhaleshwari River. The lower value was observed at D-2, representing the Sudkhira area while the highest value was observed in the D-1 location (Savar tannery area). This may be due to the tannery activities, which also indicate a high degree of ecological risk. Every sampling station was contributed by leather and dying industries. According to Table 7, sampling stations D-1 (Savar tannery), D-2 (Sudkhira), D-3 (Dhalla, fish market), D-4 (AKS dying), and D-5 (Nama Bazar) showed E values greater than 300, all of which are indicating a disastrous RI degree of ecological risk. The ecological risk index was very low (E < 100), indicating low RI risk in the Shitalakshya River, Turag River, and Tongi Canal. Table 7. Ecological risk characterization of the Peripheral Rivers in Dhaka city. a i Sampling Station E Risk Grade RI Cd Cr Ni Zn D-1 750 36.8 43.5 0.02 830.32 Disastrous risk D-2 450 3.2 16.5 0.006 469.71 Disastrous risk D-3 510 31.2 36.5 0.007 577.71 Disastrous risk D-4 570 35.6 19.5 0.015 625.11 Disastrous risk D-5 540 36 38.5 0.012 614.51 Disastrous risk Buriganga River 59.4 310.62 10.35 0.02 380.39 Disastrous risk Shitalakshya River 36 - - 0.002 36.002 Low risk Turag River - 10 1.4 0.013 11.413 Low risk Tongi Canal - 0.4 0.25 0.01 0. 66 Low risk a i b E = Ecological risk factor; E = Ecological risk index. RI It is worth mentioning that these higher values of E might be attributed to the RI presence of greater degrees of Cd at each sampling station. Phosphate fertilizers, non- ferrous metal mining or refining, and waste disposal are among the anthropogenic (result of human activity) sources of cadmium in the environment [85]. A vast amount of agricultural land and metal processing industries exist around the Dhaleshwari River. Extra cadmium accumulates in the aquatic organism and crops. Untreated waste from tanneries, unplanned urbanization, raw effluent from several dying industries, leather waste throughout the selected stretch are the plausible causes of the disastrous ecological risk. The Ecological risk indices for the other peripheral rivers were also evaluated with the information gathered from different studies [71–73,86,87] and presented in Table 7. Authors obtained an ecological risk at a level of 380.39 in the surface water of the Buriganga River according to the concentration levels reported by Sarkar et al. (2015), which also indicates disastrous level of risk in the Buriganga. However, based on the characterization by Ecological Risk Index, all the other rivers (Turag, Tongi Canal and Shitalakshya) exhibited low level of Earth 2021, 2 710 risks. Thus ecosystems are severely under threat in the Dhaleshwari and Buriganga rivers while the other rivers could maintain ecosystem without significant threat. 4. Conclusions The present study dealt with evaluating the current water quality of the Dhaleshwari river in terms of physicochemical parameters and heavy metals while the study also attempted to make a comparative assessment on pollution status among all the peripheral rivers around Dhaka City. Significant contamination was observed at every peripheral river concerning identified parameters such as dissolved oxygen (DO), total dissolved solids (TDS), 5-day biochemical oxygen demand (BOD ) and chemical oxygen demand (COD). This study also performed investigation on the status of relevant heavy metals (chromium-Cr, cadmium-Cd, nickel-Ni, zinc-Zn) pollution in different rivers of Dhaka City. The concentration levels of the toxic metals such as Cr, Cd, and Ni in the Savar tannery (D-1), Sudkhira (D-2), AKS dying (D-4), and Nama Bazar (D-5) areas of Dhaleshwari River and Buriganga river in general seemed to be of significant and of high concern warranting regular and detailed investigation and monitoring. Heavy metals pollution was further characterized in this study by ecological risk index (E ). Except for the Burganga and Dhaleshwari rivers, the ecological risk index values RI showed very low levels (E < 100) for the Shitalakshya River, Turag River, and Tongi Canal, RI indicating lower level of risk. However, the ecological risk index measured contamination intensity of heavy metals that revealed disastrous risk (E  300) at sampling stations RI D-1 (Savar tannery), D-2 (Sudkhira), D-3 (Dhalla, fish market), D-4 (AKS dying), and D-5 (Nama Bazar) in the Dhaleshwari River and disastrous level of ecological risk was also obtained in the Buriganga River. Based on all the physicochemical and toxicity-based risk characterization, the river system in Dhaka city can be termed as severely polluted based on organic and solids discharge whilst not all the rivers could be considered as significant threats to maintain ecosystems in general, except for the Dhaleshwari and Burganga rivers. A wider level and continuous comprehensive investigation will be required to confirm on the ecological characterization of the rivers. Although, it was observed that the deviation of physicochemical parameters for certain peripheral rivers of Dhaka were not significant enough from the standards, however, satisfactory conditions are yet to be expected. Furthermore, after the relocation of Hazaribagh tannery to Savar, the water quality of the Dhaleshwari river started to deteriorate and quite possibly could pose a severe threat to the ecosystem. If appropriate measures are not adopted soon enough, this will impact both the ecological and public health around the river. On the context of ever-increasing industrial growth and urbanization concerns in Dhaka city, present findings lay down additional foundation for frequent monitoring of the river systems and their tributaries. As part of the steps to abate the water pollution for river system of Dhaka City, a continual assessment of waste discharge and pollutant loadings is warranted on a regular basis. Author Contributions: Conceptualization, M.A.S.I. and N.M.; Investigation, M.A.S.I. and N.M.; Data Collection and Analysis, M.A.S.I. and M.E.H.; Investigation; M.A.S.I., M.E.H. and N.M.; Writing— original draft preparation, M.A.S.I.; Writing—review and editing, M.A.S.I. and N.M.; Supervision; N.M. and M.E.H. All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by the Undergraduate Thesis fund of the Department of Civil Engineering, University of Asia Pacific, Dhaka, Bangladesh. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Acknowledgments: The authors hereby declare that the work was part of undergraduate thesis work with support from Department of Civil Engineering at University of Asia Pacific and the Department Earth 2021, 2 711 of Soil, Water and Environment at Dhaka University in collaboration. No additional funding was received for performing any part of this study. Conflicts of Interest: The authors declare that they have no conflict of interest. References 1. Roy, S.; Banna, L.; Hossain, M.; Rahman, H. Water quality of Narai canal and Balu river of Dhaka City: An impact of industrial- ization. J. Bangladesh Agric. Univ. 2014, 12, 285–290. [CrossRef] 2. Sener ¸ , S.; ¸ Se ¸ ner, E.; Davraz, A. Evaluation of water quality using water quality index (WQI) method and GIS in Aksu River (SW-Turkey). Sci. Total. Environ. 2017, 584, 131–144. [CrossRef] 3. Mustafa, M.; Brooks, A.C. A comparative study of two seasonal floodplain aquaculture systems in Bangladesh. Water Policy 2009, 11, 69–79. [CrossRef] 4. Islam, F.; Rahman, M.; Khan, S.; Ahmed, B.; Bakar, A.; Halder, M. Heavy metals in water, sediment and some fishes of Karnofuly River, Bangladesh. Pollut. Res. 2013, 32, 715–721. 5. Hafizur, R.; Nuralam, H.; Rumainul, I. Investigation of physicochemical parameter, heavy metal in Turag river water and adjacent industrial effluent in Bangladesh. J. Sci. Technol. Environ. Inform. 2017, 5, 347–360. [CrossRef] 6. Karn, S.K.; Harada, H. Surface water pollution in three urban territories of Nepal, India, and Bangladesh. Environ. Manag. 2001, 28, 483–496. 7. Haigh, M.J. Sustainable management of headwater resources: The Nairobi’Headwater ’Declaration (2002) and beyond. Asian J. Water Environ. Pollut. 2004, 1, 17–28. 8. Kumar, R.N. An assessment of seasonal variation and water quality index of Sabarmati River and Kharicut canal at Ahmedabad, Gujarat. Electron. J. Environ. Agric. Food Chem. 2011, 10, 2248–2261. 9. Hacioglu, N.; Dulger, B. Monthly variation of some physico-chemical and microbiological parameters in Biga Stream (Biga, Canakkale, Turkey). Afr. J. Biotechnol. 2009, 8, 1929–1937. 10. Alam, M.M.; Islam, M.A.; Islam, S.; Haider, S.Z. Surface water quality of various polluted locations. J. Bangladesh Chem. Soc. 1996, 8, 129–137. [CrossRef] 11. Raknuzzaman, M.; Ahmed, M.K.; Islam, M.S.; Habibullah-Al-Mamun, M.; Tokumura, M.; Sekine, M.; Masunaga, S. Trace metal contamination in commercial fish and crustaceans collected from coastal area of Bangladesh and health risk assessment. Environ. Sci. Pollut. Res. 2016, 23, 17298–17310. [CrossRef] 12. Ahsan, M.A.; Siddique, M.A.B.; Munni, M.A.; Akbor, M.A.; Akter, S.; Mia, M.Y. Analysis of physicochemical parameters, anions and major heavy metals of the Dhaleshwari River water, Tangail, Bangladesh. Am. J. Environ. Prot. 2018, 7, 29–39. [CrossRef] 13. Ahmed, M.K.; Ahamed, S.; Rahman, S.; Haque, M.R.; Islam, M.M. Heavy metals concentration in water, sediments and their bioaccumulation in some freshwater fishes and mussel in Dhaleshwari River, Bangladesh. Terr. Aquat. Environ. Toxicol. 2009, 3, 33–41. 14. Mohanta, L.C.; Niloy, M.N.H.; Chowdhury, G.W.; Islam, D.; Lipy, E.P. Heavy metals in water, sediment and three fish species of Dhaleshwari river, Savar. Bangladesh J. Zool. 2019, 47, 263–272. [CrossRef] 15. Biplob, P.; Fatihah, S.; Shahrom, Z.; Ahmed, E. Nitrogen-removal efficiency in an upflow partially packed biological aerated filter (BAF) without backwashing process. J. Water Reuse Desalination 2011, 1, 27–35. [CrossRef] 16. Zetterberg, C.; Öfverholm, T. Carpal tunnel syndrome and other wrist/hand symptoms and signs in male and female car assembly workers. Int. J. Ind. Ergon. 1999, 23, 193–204. [CrossRef] 17. Doyle, M.P.; Herman, J.G.; Dykstra, R.L. Autocatalytic oxidation of hemoglobin induced by nitrite: Activation and chemical inhibition. J. Free. Radic. Biol. Med. 1985, 1, 145–153. [CrossRef] 18. Yuan, G.-L.; Liu, C.; Chen, L.; Yang, Z. Inputting history of heavy metals into the inland lake recorded in sediment profiles: Poyang Lake in China. J. Hazard. Mater. 2011, 185, 336–345. [CrossRef] 19. Armitage, P.D.; Bowes, M.J.; Vincent, H.M. Long-term changes in macroinvertebrate communities of a heavy metal polluted stream: The river Nent (Cumbria, UK) after 28 years. River Res. Appl. 2007, 23, 997–1015. [CrossRef] 20. Sin, S.; Chua, H.; Lo, W.; Ng, L. Assessment of heavy metal cations in sediments of Shing Mun River, Hong Kong. Environ. Int. 2001, 26, 297–301. [CrossRef] 21. Srebotnjak, T.; Carr, G.; de Sherbinin, A.; Rickwood, C. A global Water Quality Index and hot-deck imputation of missing data. Ecol. Indic. 2012, 17, 108–119. [CrossRef] 22. Islam, M.S.; Han, S.; AHMED, M.K.; Masunaga, S. Assessment of trace metal contamination in water and sediment of some rivers in Bangladesh. J. Water Environ. Technol. 2014, 12, 109–121. [CrossRef] 23. Su, S.; Xiao, R.; Mi, X.; Xu, X.; Zhang, Z.; Wu, J. Spatial determinants of hazardous chemicals in surface water of Qiantang River, China. Ecol. Indic. 2013, 24, 375–381. [CrossRef] 24. Koukal, B.; Dominik, J.; Vignati, D.; Arpagaus, P.; Santiago, S.; Ouddane, B.; Benaabidate, L. Assessment of water quality and toxicity of polluted Rivers Fez and Sebou in the region of Fez (Morocco). Environ. Pollut. 2004, 131, 163–172. [CrossRef] [PubMed] 25. Cataldo, D.; Colombo, J.; Boltovskoy, D.; Bilos, C.; Landoni, P. Environmental toxicity assessment in the Paraná river delta (Argentina): Simultaneous evaluation of selected pollutants and mortality rates of Corbicula fluminea (Bivalvia) early juveniles. Environ. Pollut. 2001, 112, 379–389. [CrossRef] Earth 2021, 2 712 26. Mohiuddin, K.; Zakir, H.; Otomo, K.; Sharmin, S.; Shikazono, N. Geochemical distribution of trace metal pollutants in water and sediments of downstream of an urban river. Int. J. Environ. Sci. Technol. 2010, 7, 17–28. [CrossRef] 27. Hobbelen, P.; Koolhaas, J.; Van Gestel, C. Risk assessment of heavy metal pollution for detritivores in floodplain soils in the Biesbosch, The Netherlands, taking bioavailability into account. Environ. Pollut. 2004, 129, 409–419. [CrossRef] [PubMed] 28. Harikumar, P.; Nasir, U.; Rahman, M.M. Distribution of heavy metals in the core sediments of a tropical wetland system. Int. J. Environ. Sci. Technol. 2009, 6, 225–232. [CrossRef] 29. Miller, C.V.; Foster, G.D.; Majedi, B.F. Baseflow and stormflow metal fluxes from two small agricultural catchments in the Coastal Plain of the Chesapeake Bay Basin, United States. Appl. Geochem. 2003, 18, 483–501. [CrossRef] 30. Dassenakis, M.; Scoullos, M.; Foufa, E.; Krasakopoulou, E.; Pavlidou, A.; Kloukiniotou, M. Effects of multiple source pollution on a small Mediterranean river. Appl. Geochem. 1998, 13, 197–211. [CrossRef] 31. Abdel-Ghani, N.; Elchaghaby, G. Influence of operating conditions on the removal of Cu, Zn, Cd and Pb ions from wastewater by adsorption. Int. J. Environ. Sci. Technol. 2007, 4, 451–456. [CrossRef] 32. Akcay, H.; Oguz, A.; Karapire, C. Study of heavy metal pollution and speciation in Buyak Menderes and Gediz river sediments. Water Res. 2003, 37, 813–822. [CrossRef] 33. Venugopal, T.; Giridharan, L.; Jayaprakash, M. Characterization and risk assessment studies of bed sediments of River Adyar-An application of speciation study. Int. J. Environ. Res. 2009, 3, 581–598. 34. Khadse, G.; Patni, P.; Kelkar, P.; Devotta, S. Qualitative evaluation of Kanhan river and its tributaries flowing over central Indian plateau. Environ. Monit. Assess. 2008, 147, 83–92. [CrossRef] 35. Mohiuddin, K.; Otomo, K.; Ogawa, Y.; Shikazono, N. Seasonal and spatial distribution of trace elements in the water and sediments of the Tsurumi River in Japan. Environ. Monit. Assess. 2012, 184, 265–279. [CrossRef] 36. Morillo, J.; Usero, J.; Gracia, I. Heavy metal distribution in marine sediments from the southwest coast of Spain. Chemosphere 2004, 55, 431–442. [CrossRef] 37. Soeprobowati, T.R.; Hariyati, R. Phycoremediation of Pb, Cd, Cu, and Cr by Spirulina platensis (Gomont) Geitler. Am. J. Biosci. 2014, 2, 165–170. [CrossRef] 38. Pueyo, M.; Sastre, J.; Hernandez, E.; Vidal, M.; López-Sánchez, J.; Rauret, G. Prediction of trace element mobility in contaminated soils by sequential extraction. J. Environ. Qual. 2003, 32, 2054–2066. [CrossRef] 39. Caeiro, S.; Costa, M.H.; Ramos, T.; Fernandes, F.; Silveira, N.; Coimbra, A.; Medeiros, G.; Painho, M. Assessing heavy metal contamination in Sado Estuary sediment: An index analysis approach. Ecol. Indic. 2005, 5, 151–169. [CrossRef] 40. Rahman, M.; Ziku, A.; Choudhury, T.R.; Ahmad, J.U.; Mottaleb, M.A. Heavy Metal Contaminations in Vegatables, Soils and River Water: A Comprehensive Study of Chilmari, Kurigram, Bangladesh. Int. J. Environ. Ecol. Fam. Urban Stud. 2015, 5, 29–42. 41. Phuong, N.M.; Kang, Y.; Sakurai, K.; Iwasaki, K.; Kien, C.N.; Van Noi, N. Levels and chemical forms of heavy metals in soils from Red River Delta, Vietnam. Water Air Soil Pollut. 2010, 207, 319–332. [CrossRef] 42. Benti, G. Assessment of heavy metals in vegetables irrigated with Awashi River in selected farms around Adama town, Ethiopia. Afr. J. Environ. Sci. Technol. 2014, 8, 428–434. 43. Yadav, A.; Yadav, P.K.; Shukla, D. Investigation of heavy metal status in soil and vegetables grown in urban area of Allahabad, Uttar Pradesh, India. Int. J. Sci. Res. Publ. 2013, 3, 1–7. 44. Prabu, P. Impact of heavy metal contamination of Akaki River of Ethiopia on soil and metal toxicity on cultivated vegetable crops. Electron. J. Environ. Agric. Food Chem. 2009, 8, 818–827. 45. Ammann, A.A. Speciation of heavy metals in environmental water by ion chromatography coupled to ICP–MS. Anal. Bioanal. Chem. 2002, 372, 448–452. [CrossRef] 46. Majumdar, R.C. History of Ancient Bengal; G. Bharadwaj & Co.: Hyderabad, India, 1971. 47. Cenci, R.; Martin, J.-M. Concentration and fate of trace metals in Mekong River Delta. Sci. Total. Environ. 2004, 332, 167–182. [CrossRef] 48. Wade, T.J.; Pai, N.; Eisenberg, J.N.; Colford, J.M., Jr. Do US Environmental Protection Agency water quality guidelines for recreational waters prevent gastrointestinal illness? A systematic review and meta-analysis. Environ. Health Perspect. 2003, 111, 1102–1109. [CrossRef] 49. Nahian, M.; Islam, M.; Kabir, M.; Tusher, T.R.; Sultana, N. Seasonal variation of water quality in Gowain river near Ratargul swamp forest, Sylhet, Bangladesh. Humayun and Tusher, Tanmoy Roy and Sultana, Nargis, Seasonal Variation of Water Quality in Gowain River near Ratargul Swamp Forest, Sylhet, Bangladesh. Grassroots J. Nat. Resour. 2018, 1, 26–36. [CrossRef] 50. Fatema, K.; Begum, M.; Al Zahid, M.; Hossain, M. Water quality assessment of the river Buriganga, Bangladesh. J. Biodivers. Conserv. Bioresour. Manag. 2018, 4, 47–54. [CrossRef] 51. Islam, M.; Rehnuma, M.; Tithi, S.; Kabir, M.; Sarkar, L. Investigation of water quality parameters from Ramna, Crescent and Hatirjheel Lakes in Dhaka City. J. Environ. Sci. Nat. Resour. 2015, 8, 1–5. [CrossRef] 52. Kabir, E.; Kabir, M.; Islam, S.; Mia, C.; Begum, N.; Chowdhury, D.; Sultana, S.; Rahman, S. Assessment of effluent quality of Dhaka export processing zone with special emphasis to the textile and dying industries. Jahangirnagar Univ. J. Sci. 2002, 25, 137–138. 53. Trivedy, R.K. Ecology and Pollution of Indian Rivers; Ashish Pub. House: Delhi, India, 1988. 54. Hakanson, L. An ecological risk index for aquatic pollution control. A sedimentological approach. Water Res. 1980, 14, 975–1001. [CrossRef] Earth 2021, 2 713 55. Arefin, M.T.; Rahman, M.M. Heavy metal contamination in surface water used for irrigation: Functional assessment of the Turag River in Bangladesh. J. Appl. Biol. Chem. 2016, 59, 83–90. [CrossRef] 56. Gan, J.; Jia, X.; Lin, Q.; Li, C.; Wang, Z.; Zhou, G.; Wang, X.; Cai, W.; Lu, X. A primary study on ecological risk caused by the heavy metals in coastal sediments. J. Fish. China/Shuichan Xuebao 2000, 24, 533–538. 57. Srivastava, R.; Sinha, A.; Pande, D.; Singh, K.; Chandra, H. Water quality of the river Ganga at Phaphamau (Allahabad)—Effect of mass bathing during Mahakumbh. Environ. Toxicol. Water Qual. Int. J. 1996, 11, 1–5. [CrossRef] 58. Simpi, B.; Hiremath, S.; Murthy, K.; Chandrashekarappa, K.; Patel, A.N.; Puttiah, E. Analysis of water quality using physico- chemical parameters Hosahalli Tank in Shimoga District, Karnataka, India. Glob. J. Sci. Front. Res. 2011, 11, 31–34. 59. Saravanan, V. Technological transformation and water conflicts in the Bhavani River Basin of Tamil Nadu, 1930–1970. Environ. Hist. 2001, 7, 289–334. [CrossRef] 60. Mohanakavitha, T.; Shankar, K.; Divahar, R.; Meenambal, T.; Saravanan, R. Impact of industrial wastewater disposal on surface water bodies in Kalingarayan canal, Erode district, Tamil Nadu, India. Arch. Agric. Environ. Sci. 2019, 4, 379–387. [CrossRef] 61. Usharani, K.; Umarani, K.; Ayyasamy, P.; Shanthi, K.; Lakshmanaperumalsamy, P. Physico-chemical and bacteriological character- istics of Noyyal River and ground water quality of Perur, India. J. Appl. Sci. Environ. Manag. 2010, 14. [CrossRef] 62. Standard, B. The Environment Conservation Rules 1997; Government of the People’s Republic of Bangladesh: Dhaka, Bangladesh, 63. Agbaire, P.; Obi, C. Seasonal variations of some physico-chemical properties of River Ethiope water in Abraka, Nigeria. J. Appl. Sci. Environ. Manag. 2009, 13. [CrossRef] 64. Premlata, V. Multivariant analysis of drinking water quality parameters of lake Pichhola in Udaipur, India. Biological Forum. 2009, 1, 86–91. 65. Sawyer, C.N.; McCarty, P.L.; Parkin, G.F. Chemistry for Environmental Engineering and Science; McGraw-Hill: New York, NY, USA, 2003; Volume 5. 66. Vishwakarma, C.A.; Sen, R.; Singh, N.; Singh, P.; Rena, V.; Rina, K.; Mukherjee, S. Geochemical characterization and controlling factors of chemical composition of spring water in a part of Eastern Himalaya. J. Geol. Soc. India 2018, 92, 753–763. [CrossRef] 67. Brady, N.C.; Weil, R.R.; Weil, R.R. The Nature and Properties of Soils; Prentice Hall Upper Saddle River: Hoboken, NJ, USA, 2008; Volume 13. 68. National Recommended Water Quality Criteria. United States Environmental Protection Agency, Office of Water, Office of Science and Technology. 2009. Available online: https://www.epa.gov/wqc/national-recommended-water-quality-criteria-tables (accessed on 23 July 2021). 69. Doganlar ˘ , Z.B.; Atmaca, M. Influence of airborne pollution on Cd, Zn, Pb, Cu, and Al accumulation and physiological parameters of plant leaves in Antakya (Turkey). Water Air Soil Pollut. 2011, 214, 509–523. [CrossRef] 70. Sarkar, M.; Rahman, A.L.; Islam, J.; Ahmed, K.; Uddin, M.; Bhoumik, N. Study of hydrochemistry and pollution status of the Buriganga river, Bangladesh. Bangladesh J. Sci. Ind. Res. 2015, 50, 123–134. [CrossRef] 71. Mokaddes, M.; Nahar, B.; Baten, M. Status of heavy metal contaminations of river water of Dhaka Metropolitan City. J. Environ. Sci. Nat. Resour. 2012, 5, 349–353. [CrossRef] 72. Biswas, S.; Rahman, M.; Bahar, A.-U.; Debnath, S. Status of heavy metal in the peripheral rivers around Dhaka city. OIDA Int. J. Sustain. Dev. 2015, 8, 39–44. 73. World Health Organization. Guidelines for Drinking-Water Quality; World Health Organization: Geneva, Switzerland, 1993. 74. Shaw, J. Milk: The Mammary Gland and Its Secretion; Food and Agriculture Organization of The United Nations: Rome, Italy, 2016; p. 89. 75. Ahammed, R.; Harvey, N. Evaluation of environmental impact assessment procedures and practice in Bangladesh. Impact Assess. Proj. Apprais. 2004, 22, 63–78. 76. World Health Organization. Guidelines for Safe Recreational Water Environments: Coastal and Fresh Waters; World Health Organiza- tion: Geneva, Switzerland, 2003; Volume 1. 77. Hamed, M.A. Chemical forms of copper, zinc, lead and cadmium in sediments of the northern part of the Red Sea, Egypt. Pak. J. Mar. Sci. 2007, 16, 69–78. 78. FY 2013 Annual Performance Report FY 2015 Annual Plan Data Quality Records. n.d. Available online: https://nepis.epa.gov/ Exe/ZyNET.exe/P100M5MS.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2011+Thru+2015&Docs=&Query=&Time= &EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay= &IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C11thru15%5CTxt%5C000 00015%5CP100M5MS.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1& FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL& Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL (accessed on 23 July 2021). 79. El-Ebiary, E.; Wahbi, O.; El-Greisy, Z. Influence of dietary cadmium on sexual maturity and reproduction of red tilapia. Egypt J. Aquat. Res. 2013, 39, 313–317. [CrossRef] 80. Fauser, P.; Strand, J.; Vorkamp, K. Risk assessment of added chemicals in plastics in the Danish marine environment. Mar. Pollut. Bull. 2020, 157, 111298. [CrossRef] Earth 2021, 2 714 81. Homady, M.; Hussein, H.; Jiries, A.; Mahasneh, A.; Al-Nasir, F.; Khleifat, K. Survey of some heavy metals in sediments from vehicular service stations in Jordan and their effects on social aggression in prepubertal male mice. Environ. Res. 2002, 89, 43–49. [CrossRef] [PubMed] 82. Ahmad, M.; Islam, S.; Rahman, S.; Haque, M.; Islam, M. Heavy metals in water, sediment and some fishes of Buriganga River, Bangladesh. Int. J. Environ. Res. 2010, 4, 321–332. 83. Mgbenu, C.N.; Egbueri, J.C. The hydrogeochemical signatures, quality indices and health risk assessment of water resources in Umunya district, southeast Nigeria. Appl. Water Sci. 2019, 9, 1–19. [CrossRef] 84. Bhuiyan, M.A.H.; Suruvi, N.I.; Dampare, S.B.; Islam, M.; Quraishi, S.B.; Ganyaglo, S.; Suzuki, S. Investigation of the possible sources of heavy metal contamination in lagoon and canal water in the tannery industrial area in Dhaka, Bangladesh. Environ. Monit. Assess. 2011, 175, 633–649. [CrossRef] [PubMed] 85. ATSDR (Agency for Toxic Substances and Disease Registry). Prepared by Clement International Corp., Under Contract No. 205-88-0608. 2000. Available online: https://www.atsdr.cdc.gov/ (accessed on 23 July 2021). 86. Rahman, M.; Islam, M.; Khan, M. Status of heavy metal pollution of water and fishes in Balu and Brahmaputra rivers. Progress. Agric. 2016, 27, 444–452. [CrossRef] 87. Shama, S.; Moustafa, M.; Gad, M. Removal of heavy metals Fe3+, Cu2+, Zn2+, Pb2+, Cr3+ and Cd2+ from aqueous solutions by using eichhornia crassipes. Port. Electrochim. Acta 2010, 28, 125–133. [CrossRef] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Earth Multidisciplinary Digital Publishing Institute

Assessment of Physicochemical Properties and Comparative Pollution Status of the Dhaleshwari River in Bangladesh

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Article Assessment of Physicochemical Properties and Comparative Pollution Status of the Dhaleshwari River in Bangladesh 1 2 1 , Md. Al Sadikul Islam , Mohammad Enayet Hossain and Nehreen Majed * Department of Civil Engineering, University of Asia Pacific, Dhaka 1205, Bangladesh; sadikul96@outlook.com Department of Soil, Water and Environment, Dhaka University, Dhaka 1000, Bangladesh; enayetswe@du.ac.bd * Correspondence: nehreen-ce@uap-bd.edu; Tel.: +88-01819206394 Abstract: The Dhaleshwari river which flows near Dhaka, the capital of Bangladesh, is currently under threat due to the recent relocation of the Hazaribagh tannery to the Savar area. This study investigated the physicochemical parameters of water quality along with the heavy metal levels in the Dhaleshwari river and performed a comparative analysis among the peripheral rivers around Dhaka City. Surface water quality parameters such as total dissolved solids (TDS), biochemical oxygen demand (BOD ), and chemical oxygen demand (COD) obtained for the Dhaleshwari river deviated by as much as 90% from World Health Organization (WHO) standards in certain instances due to direct discharge from untreated point sources. Concentrations of toxic metals such as chromium (Cr), cadmium (Cd), and nickel (Ni) were above the Food and Agriculture Organization (FAO) standards for heavy metals in surface waters. Strong correlations among the heavy metals indicated significant linear dependences. Based on the physicochemical and toxicity-based characterization, the river system in Dhaka city can be termed as severely polluted with respect to organic and solids discharge, while ecological risk indices (E ) indicated disastrously high risk in the Dhaleshwari and Buriganga RI Citation: Islam, M.A.S.; Hossain, rivers. The study outcomes emphasize the necessity of frequent investigation while controlling the M.E.; Majed, N. Assessment of point and nonpoint urban pollution sources discharging into the peripheral rivers of Dhaka city. Physicochemical Properties and Comparative Pollution Status of the Keywords: river water; pollution; Dhaleshwari; heavy metals; wastewater; ecological risk Dhaleshwari River in Bangladesh. Earth 2021, 2, 696–714. https:// doi.org/10.3390/earth2040041 1. Introduction Academic Editor: Laura Bulgariu Life and health depend on freshwater, which is a vital issue to public health and welfare. Almost all civilizations on Earth are inextricably linked by rivers, which are Received: 9 August 2021 the places where they originated and evolved from. Once, the rivers of Bangladesh Accepted: 26 September 2021 Published: 30 September 2021 were its lifeblood, but pollution is now a major national problem, mainly owing to the ever-increasing development activities surrounding riverbank areas that lack appropriate Publisher’s Note: MDPI stays neutral environmental protection [1,2]. Such rivers are vast reservoirs for numerous fish and with regard to jurisdictional claims in different aquatic species [3]. The river water is utilized inconceivably for maintaining the published maps and institutional affil- water system, energy generation, navigation, amusement, and numerous industrial and iations. domestic purposes [4]. Changes in the quality of inland surface water are typically caused by industrial operations and seasonal variations in river flow [5]. Rapid and unplanned urban sprawl, industrial growth, and population pressure have made the city an environmentally polluted area [6,7]. The waterways of Bangladesh have become more polluted due to the excessive Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. usage of pesticides in the surrounding river lands, unrestricted urbanization, lack of well- This article is an open access article planned construction along riverbanks, and population expansion. In Bangladesh, surface distributed under the terms and water is used for drinking purposes, farming, and fishing [8,9]. Mills and industries are conditions of the Creative Commons dumping chemical and hazardous wastes into numerous rivers posing health risks to Attribution (CC BY) license (https:// people. Since the dawn of society and progress, threats continue to exist side by side creativecommons.org/licenses/by/ with development initiatives. As a young delta, the river channels are constantly shifting. 4.0/). Earth 2021, 2, 696–714. https://doi.org/10.3390/earth2040041 https://www.mdpi.com/journal/earth Earth 2021, 2 697 The peripheral rivers of Dhaka city are vulnerable to natural calamities, climate-change- related problems, transboundary challenges, and, last but not the least, anthropogenic interventions [10]. In recent years, water quality issues have emerged with concerns surrounding water flow and, subsequently, the water bodies’ carrying capacity. In central Dhaka, the Dhaleshwari River is one of the main distributaries on the left bank of the Jamuna River, which has a length of 160 km and has an average depth of around 37 m [11,12]. In its surrounding territories, this river makes a significant contribution to socio-economic development [13]. The Dhaleshwari receives substantial amounts of munic- ipal waste, surface runoff, unregulated industrial waste, and directly or indirectly treated sewage waste from Saver City [14]. These contaminants pollute the river water making it unsuitable for use and harming aquatic lifeforms. Most notably, the physicochemical quality of the river has deteriorated, and most of the water quality parameters do not meet the minimum standard guidelines for safe drinking water by World Health Organization (WHO). Contaminated water intake may be associated with several illnesses such as can- cer, congenital abnormalities, central nervous system problems, and endocrine system disturbance and heart disease. Blue baby diseases, gastric cancer, and other disorders are also associated with nitrate and nitrite-contaminated water diseases [15–17]. Biological diversity as well as other aquatic communities, including fish, are declining, putting the rivers of Dhaka, such as Dhaleshwari, at risk of becoming “dead” river in the coming days. The government of Bangladesh relocated the tannery industries from their previous site in Hazaribagh beside the Buriganga river, to a new location in Savar due to the dangerous impact that the tannery wastes were posing for human and environmental health in Hazaribagh. Modernization of the tanneries and treatment of effluents in a contemporary central effluent treatment plant (CETP) have been the primary goals of this move, which would result in a waste management system for the tannery industry that is more environmentally sound. However, as claimed by tannery industrial park residents, the water quality of the Dhaleshwari river has worsened, and this has been published in several local newspapers. Improper release of waste into the waterway, circumventing the mainline of the CETP, was the subject of several frightening media reports. CETP effluent released from the tannery industrial park has not been characterized in detail for its influence on the water quality of the surrounding river stretch. This warrants thorough investigation and characterization of water quality in the vicinity of the tannery. On another alarming note, heavy metals contamination in the aquatic ecosystem has drawn global attention in recent years because of the persistent nature, abundance, and prevalence of the same [18–20]. The rapid expansion of the world population, household activities, agricultural and industrial output have resulted in the release of large quantities of toxics such as heavy metals into rivers across the world [21–23]. Severe contamination of water, soil, and atmosphere are observed with unprecedented accumulation and dispersion of heavy metals, affecting marine and aquatic species [24–27]. Rivers constitute predominant pathways for the transport of heavy metals [28,29], and several poisonous metals eventually become part of numerous riverine frameworks [30] due to absorption, precipitation, solubility, and complexity processes [30–32], affecting their actions and bioavailability [31,32]. Due to the practice of dumping untreated commercial and residential trash into water bodies, metal concentrations are increasing in river water [33,34]. The nature of metals in natural water is dependent on the composition of the water substrate, suspended sedi- ment, and the quality of the water [35]. The Association of metals in sediments of various geological stages has a significant impact on the cumulative behavior of heavy metals in aquatic environments [36]. In predicting potential pollution, flexibility, and bioavailability, geochemical speciation and metal distribution in the given chemical fractions are generally used [36–39]. River water polluted with heavy metals such as cadmium (Cd), chromium (Cr), zinc (Zn), and nickel (Ni) can damage crops such as vegetables and rice [40–44]. The assessment of the contamination by and transmission of heavy metals in the riverine environment is therefore essential. Heavy metals in the concerned peripheral rivers around Dhaka city may be a result of human activities, such as mining and the disposal of improp- Earth 2021, 2, FOR PEER REVIEW 3 erally used [36–39]. River water polluted with heavy metals such as cadmium (Cd), chro- mium (Cr), zinc (Zn), and nickel (Ni) can damage crops such as vegetables and rice [40– 44]. The assessment of the contamination by and transmission of heavy metals in the riv- erine environment is therefore essential. Heavy metals in the concerned peripheral rivers around Dhaka city may be a result of human activities, such as mining and the disposal of improperly handled or untreated effluent from industries such as tanneries, battery Earth 2021, 2 698 industries, steel plants, and thermal power plants, as well as pesticides used in agricul- tural fields and compost containing heavy metals [45]. The Aim of the Study erly handled or untreated effluent from industries such as tanneries, battery industries, steel plants, and thermal power plants, as well as pesticides used in agricultural fields and In the context of the facts discussed above, the present study aims to evaluate the compost containing heavy metals [45]. pollution condition of the Dhaleshwari river due to the impact of the newly shifted tan- nery industrial park as compared to the Buriganga river in general. This study also makes The Aim of the Study a comparative assessment of the surface water quality among all the peripheral rivers In the context of the facts discussed above, the present study aims to evaluate the pollution around Dh condition aka City of the that h Dhaleshwari as rarely river been due accomp to the impact lished of with re the newly spect shifted to bot tannery h physicochem- industrial park as compared to the Buriganga river in general. This study also makes a ical status of water quality and heavy metal contamination. A particular focus of this comparative assessment of the surface water quality among all the peripheral rivers around study consists of evaluating the ecological threat emanating from the presence of heavy Dhaka City that has rarely been accomplished with respect to both physicochemical status metals in the surface water of the Dhaleshwari River which would further pave and ne- of water quality and heavy metal contamination. A particular focus of this study consists cessitate the ways towards mitigating the pollution and rehabilitating the river. of evaluating the ecological threat emanating from the presence of heavy metals in the surface water of the Dhaleshwari River which would further pave and necessitate the ways 2. Materials and Methods towards mitigating the pollution and rehabilitating the river. 2.1. Description of the Study Area and River Water Sampling 2. Materials and Methods 2.1. Description of the Study Area and River Water Sampling The peripheral river system of Dhaka city mainly consists of three different systems; Dhaleswari-Kaliganga System, Bangsi-Turag-Buriganga-Dhaleshwari System, and Balu- The peripheral river system of Dhaka city mainly consists of three different systems; Dhaleswari-Kaliganga System, Bangsi-Turag-Buriganga-Dhaleshwari System, and Balu- Lakhya System (Figure 1). The Dhaleswari-Kaliganga and Bangshi-Turag-Buriganga river Lakhya System (Figure 1). The Dhaleswari-Kaliganga and Bangshi-Turag-Buriganga river systems are to the west, and the Balu-Lakhya river system is to the east of Dhaka. The systems are to the west, and the Balu-Lakhya river system is to the east of Dhaka. The Dhaleshwari River originates from the Jamuna River near the north-western edge of Tan- Dhaleshwari River originates from the Jamuna River near the north-western edge of Tangail gail district and eventually reaches the Shitalakshya river near the district of Narayanganj. district and eventually reaches the Shitalakshya river near the district of Narayanganj. This This merged flow goes towards the south to combine with the Meghna River [46]. All the merged flow goes towards the south to combine with the Meghna River [46]. All the samples samplefor s fo the r th present e present investigation investigation were collected were frcol omlected selected from locations selected where lo the cation river s where the flows through the Savar District industrialized area. river flows through the Savar District industrialized area. Figure 1. GIS Map of the Sampling Stations along Dhaleshwari River. Figure 1. GIS Map of the Sampling Stations along Dhaleshwari River. Identified sampling stations were selected based on the intensity of industrialized Identified sampling stations were selected based on the intensity of industrialized zones and presence of waste disposal points beside the banks of the rivers. In the present zones and presence of waste disposal points beside the banks of the rivers. In the present study, five of the following places along the river were chosen: Savar Tannery (D-1), study, five of the following places along the river were chosen: Savar Tannery (D-1), Sudkhira (D-2), Dhalla (fish market) (D-3), AKS dying (D-4), and Nama Bazar (D-5) at Sudkhira (D-2), Dhalla (fish market) (D-3), AKS dying (D-4), and Nama Bazar (D-5) at Savar district in Bangladesh (Figure 1). Global positioning system (GPS) coordinates were used to precisely locate each sampling station. The identification of the sampling stations and distances from the Savar Tannery are provided in Table 1. Earth 2021, 2, FOR PEER REVIEW 4 Savar district in Bangladesh (Figure 1). Global positioning system (GPS) coordinates were used to precisely locate each sampling station. The identification of the sampling stations and distances from the Savar Tannery are provided in Table 1. Earth 2021, 2 699 Table 1. Identification of sampling stations and distance from D-1 in Dhaleshwari River. Sampling Stations Type of Discharge Distance from Savar Tannery (km) Table 1. Identification of sampling stations and distance from D-1 in Dhaleshwari River. D-1 Industrial 0 D-2 Municipal 1.7 Distance from Savar Tannery Sampling Stations Type of Discharge D-3 Industrial 3.7 (km) D-4 Industrial 4.1 D-1 Industrial 0 D-5 Industrial 6.2 D-2 Municipal 1.7 D-3 Industrial 3.7 D-4 Industrial 4.1 The peripheral rivers around Dhaka City are depicted in Figure 2, with the red boxes D-5 Industrial 6.2 showing the sampling locations. A minimum average of three samples was collected from each of the Turag, Tongi Canal, Balu, Buriganga, and Shitalakhya rivers. The sampling The peripheral rivers around Dhaka City are depicted in Figure 2, with the red boxes stations were chosen along the zones of concentrated levels of industrial and agricultural showing the sampling locations. A minimum average of three samples was collected from activities with numerous point sources and non-point sources of contamination. Different each of the Turag, Tongi Canal, Balu, Buriganga, and Shitalakhya rivers. The sampling indu stations strial wer sec e chosen tors such along as the lea zones therof , tex concentrated tiles, and levels metal of industrial processing andcon agricultu stitute ral the point activities with numerous point sources and non-point sources of contamination. Different sources. Other industries considered as point sources include power plants, fertilizer and industrial sectors such as leather, textiles, and metal processing constitute the point sources. pharmaceutical plants, and industries that dye fabrics and produce batteries or ink, as Other industries considered as point sources include power plants, fertilizer and pharma- well as metal melting plants. In addition, waste disposal points, toxic sewage, terminals, ceutical plants, and industries that dye fabrics and produce batteries or ink, as well as metal and landing stations also constitute point sources and contribute to pollution. Twenty melting plants. In addition, waste disposal points, toxic sewage, terminals, and landing samples in total were collected from all the rivers for physicochemical analysis, and five stations also constitute point sources and contribute to pollution. Twenty samples in total add wer itiona e collected l sam fr ples om all were the rivers obtaifor ned physi from cochemical Dhaleshwa analysis, ri River and five for additional heavy met samples al analysis. Un- were obtained from Dhaleshwari River for heavy metal analysis. Unfiltered samples of filtered samples of water were obtained from the middle of the river course. The samples water were obtained from the middle of the river course. The samples were then placed were then placed into 100 mL polypropylene bottles, and then the bottles were sealed. In into 100 mL polypropylene bottles, and then the bottles were sealed. In each polypropylene each polypropylene bottle, 1 mL of ultrapure nitric acid was added to achieve a pH of ~1 bottle, 1 mL of ultrapure nitric acid was added to achieve a pH of ~1 [47] before transferring [47] before transferring to the Department of Soil, Water and Environment Laboratory of to the Department of Soil, Water and Environment Laboratory of the University of Dhaka the University of Dhaka for heavy metals analysis. The standard sampling procedure was for heavy metals analysis. The standard sampling procedure was followed to collect all samples at every single sampling station [48–52]. followed to collect all samples at every single sampling station [48–52]. Figure 2. GIS Map Showing Peripheral Rivers around Dhaka city (boxes representing the sampling Figure 2. GIS Map Showing Peripheral Rivers around Dhaka city (boxes representing the sam- stretches along the rivers). pling stretches along the rivers). 2.2. Analysis of Physicochemical Parameters and Heavy Metals for Water Samples Water samples collected from all the rivers were analyzed for the physicochemical parameters in the Environmental Engineering Laboratory, Department of Civil Engineering, Earth 2021, 2 700 University of Asia Pacific. Standard instruments were used to test the conductivity, total dissolved solids (TDS), pH, and dissolved oxygen (DO). Electrical conductivity (EC) and total suspended solids (TSS) were assessed by a model ‘CTS-406 meter manufactured by EZDO (Taipei City, Taiwan); pH was determined by a B-221 pH meter (Twin, Santee, USA), and DO was assessed by a model ’YK-22DO’ dissolved oxygen meter (EZDO, Taipei City, Taiwan). Chemical oxygen demand (COD) was determined by using condensation and oxi- dation with potassium dichromate. All the heavy metals such as cadmium (Cd), chromium (Cr), nickel (Ni), and zinc (Zn) were analyzed in the Department of Soil, Water, and En- vironment at the University of Dhaka. The toxic metal concentrations were calculated by an “AA-7000’ atomic absorption spectrometer manufactured by Shimadzu (South San Francisco, USA). For all measurements an accurate ‘ABS 220-4’ precision electrical balance manufactured by KERN (Ziegelei, Balingen, Germany) was used. Preconcentrated samples were filtered using a nylon membrane filter (47 mm diameter, Whatman, Washington, DC, USA) to determine hazardous metals concentration [53]. For heavy metal analysis, 100 mL of each sample was collected and placed in a Pyrex volumetric flask. 1 M HCl (9 mL) and 1 M HNO (3 mL) were added next. The volumetric flask was carefully heated in a sand bath placed in a fume hood to reduce the moisture level. Deionized water was added to the sample after the flask was cooled to room temperature. The filtrate was collected in a 250 mL high density polyethylene screw-cap (HDPE) plastic container tube with a polypropylene/low density polyethylene (LDPE)-lined cap; Thermo Scientific, Washington, DC, USA). Finally samples were retained for the calculation of the concentration of the metals. The atomic absorption spectrometer (AAS) was calibrated for all the metals by running different standard concentrations. Three observations of each data point were averaged. In this case, the detection limit was set at 0.001 mg/L. An oven (GAF-7000, ESCO, Changi South Street, Singapore) was used to test the amounts of the metals present. 2.3. Multivariate Statistical Analysis Pearson’s correlation and linear regression analysis was performed to evaluate the relationship between the metals to validate the multivariate analysis (SPSS v.25, Armonk, NY, USA). The map showing the locations of the Dhaleshwari River sampling stations was generated using ArcGIS 10.3 (Esri Bangladesh, Dhaka, Bangladesh). 2.4. Assessment of Ecological Risk Hakanson [54] suggested the possible ecological risk index approach from a sedimen- tology aspect first to determine the natural and environmental behavior of heavy metal pollutants. A single coefficient of pollution, an indicator of a heavy metal toxic reaction, an exact measure of pollution, and a possible ecological risk index are included in the process. Ecological risk index (E ) was obtained by following equations [54]: RI i i i i E = T (C /C ) r r o E = E RI å r i i where C and C are the concentrations of particular heavy metals and their permitted i i reference value, respectively, and E represents an ecological risk factor. T is the toxicity r r factor for each metal (Cd = 30, Cr = 2, Ni = 5, and Zn = 1) [53]. E represents the ecological RI risk that determines how sensitive biological populations to particular metals are in the area being considered. Table 2 shows the ranges of the indices of E and E based on r RI which the categorization of risk was evaluated for the rivers. Higher values of E and E RI indicate higher risks for the ecosystem. Wastewater does not have a standard value for assessing ecological risks. Thus, classification of ecological risk exposed to toxic metals was consulted, which is provided below: Earth 2021, 2 701 Table 2. Classification of ecological risk index (E ) of heavy metal pollution [55,56]. RI E Classification r RI E < 30 E < 100 Low risk r RI 30  E < 50, 100  E < 150 Moderate risk r RI 150  E < 200 Considerable risk 50  E < 100 r RI 100  E < 150 200  E < 300 Very high risk r RI E  150 E  300 Disastrous risk r RI 3. Results and Discussion 3.1. Assessment of Physicochemical Parameters of Surface Water Surface water sampled from all the rivers in Dhaka City were analyzed for various water quality indicators. Table 3 summarizes the results on the assessment of physico- chemical characterization of the peripheral rivers around Dhaka City along with the water quality guidelines established by the WHO and Environmental Conservation Rule (ECR). Average values of all the parameters that were obtained from sampling at multiple locations have been presented in Table 3 that provides a comparative scenario in a snapshot. The Dhaleshwari River water was dark in color and had an acrid odor during the period of the study. The pH value varied from 6.9 to 11.2, along with the sampling locations of the river. The maximum pH value was observed at Sampling station D-1 (Savar Tannery), and the minimum pH value was recorded at Sampling station D-3 (Dhalla, fish market). Table 3. Results of Physicochemical properties of the peripheral rivers around Dhaka City. Average  Standard Error of Mean WHO Parameter Unit ECR’97 Dhaleshwar Buriganga Shitalakshya (2011) Turag River Tongi Canal Balu River River River River pH 6.5–8.5 6.5–8.5 8.04  0.14 6.7  0.17 6.66  0.15 7.23  0.14 6.9  0.06 7.1  0.06 TSS - 619.6  107.19 385  61.44 556.33  92.59 605  131.43 278.33  58.9 368.33  80.84 TDS mg/L 1000 1364.6  321.35 235  2.88 475  2.88 46.66  2.33 241.66  6 930  138. 68 BOD mg/L >6 5 26.44  7.61 41.33  4.97 33.33  3.48 41.33  4.63 24.66  6.88 34.5  3.67 COD mg/L 10 461.74  110.36 675.33  371.62 247.86  35.14 602.76  145.92 250.56  40.78 351.4  28.87 DO mg/L >5 4–6 2.052  0.97 0.9  0.17 3.96  0.29 2.56  0.37 2.2  0.51 2.13  0.52 EC S/cm 1000 1709.34  204.07 987.33  68.71 1283.33  92.79 655  400 620.67  342.13 710  355.01 a b The Environment Conservation Rules, 1997; World Health Organization, 2011. m m Figures 3 and 4 represent Max Vs Min concentrations of pH and TDS, respectively for the peripheral rivers of Dhaka, along with the WHO standards in dotted lines. The pH value was within the standard limit in the study, as assessed for the other peripheral rivers in Dhaka City. Total dissolved solids (TDS) primarily represents the different types of minerals, alkalis, some colloidal and dissolved solids in water, some acids, sulfates, metallic ions, etc., [52]. TDS in the water of the Dhaleshwari River ranged from 412 to 3278 mg/L with the maximum level of TDS obtained at sampling station D-1 (Savar Tannery) and the minimum level at sampling station D-5 (Nama Bazar) (Figure 4). Except for Savar tannery (D-1) and Sudkhira (D-2), all sampling stations exhibited values below the permitted level of WHO guidelines (1000 mg/L) for Dhaleshwari River. The water becomes more turbid and saltier when the TDS level exceeds the allowable limit of 1000 mg/L, which has a negative impact on aquatic life [57,58]. Consequently, it has an ultimate effect on the human, crop, and livestock. During the monsoon season, runoff water flow may cause some variance, but this volatility has impacted the irrigation system. Effluents from dyeing units might potentially be a contributing factor to the elevated TDS levels reported in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). Earth 2021, 2, FOR PEER REVIEW 7 Earth 2021, 2, FOR PEER REVIEW 7 in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration Earth 2021, 2 702 was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). (Figure 4). m m m m m m Figure Figure 3. 3. Max Max vs. vs. Min Min Concentrations Concentrations of pH of pH for the for t peripheral he peripher rivers al rive of Dhaka rs of Dh with aka wit WHOh WHO Figure 3. Max vs. Min Concentrations of pH for the peripheral rivers of Dhaka with WHO standar standards ds in in dotted dotte lines d li(6.5–8.5). nes (6.5–8.5). standards in dotted lines (6.5–8.5). m m m m Figure 4. Max m vs. Min m Concentration of TDS for the peripheral rivers of Dhaka with WHO Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO standards in dotted lines (1000 mg/L). standards in dotted lines (1000 mg/L). standards in dotted lines (1000 mg/L). m m Figures 5 and 6 represent Max vs. m Min Concentrations m of BOD and DO for all Figures 5 and 6 represent Maxm vs. Minm Concentrations of BOD 5 5 and DO for all the Figures 5 and 6 represent Max vs. Min Concentrations of BOD5 and DO for all the the peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of of BOD is the best single test for evaluating organic contamination and has significant BOD5 is the best single test for evaluating organic contamination and has significant rele- BOD5 is the best single test for evaluating organic contamination and has significant rele- relevance in water quality evaluation [60]. The BOD ranged from 11 to 45 mg/L for the vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). The observed BOD levels in the water samples indicated organic waste in the Dhaleshwari Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). river [61]. Among the sampling stations, the highest BOD was found at Sampling station The observed BOD5 levels in the water samples indicated organic waste in the The observed BOD5 levels in the water samples indicated organic waste in the D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sampling station Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD limits are 0.2 mg/L for pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irrigation [62]. pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are Since the sampling stations run through the most heavily populated and industrialized 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- region along the riverbank, the BOD was greater along the selected stretch in Dhaleshwari gation [62]. Since the sampling stations run through the most heavily populated and in- than it was along the other stretches. gation [62]. Since the sampling stations run through the most heavily populated and in- Organic materials are also discharged along with the effluent as a result of poor- dustrialized region along the riverbank, the BOD5 was greater along the selected stretch dustrialized region along the riverbank, the BOD5 was greater along the selected stretch functioning of the sewage treatment plants, storm discharges, agricultural slurries, domes- in Dhaleshwari than it was along the other stretches. in Dhaleshwari than it was along the other stretches. tic waste (waste from humans and food) and industrial waste (food industries, tannery, and dyeing) and silage liquor, thereby the Dhaleshwari River can accumulate various organic and chemical pollutants. BOD levels varied within 33–49 mg/L for the Buriganga River, 30–39 mg/L for the Shitalakshya River, 32–49 mg/L for the Turag River, 27–39 mg/L for the Tongi Canal, and 15–38 mg/L for the Balu River (Figure 5). This reveals that the discharge of organic substances and subsequent pollution is commonly happening in general for all the peripheral rivers at comparable rates. m m m m Figure 5. Max vs. Min Concentration of BOD5 in the peripheral rivers of Dhaka with WHO Figure 5. Max vs. Min Concentration of BOD5 in the peripheral rivers of Dhaka with WHO standards (5 mg/L). standards (5 mg/L). Earth 2021, 2, FOR PEER REVIEW 7 in other areas with dyeing facilities [59]. For the other peripheral rivers, TDS concentration was obtained within the permissible limit except for the Shitalakshya River (1200 mg/L) (Figure 4). m m Figure 3. Max vs. Min Concentrations of pH for the peripheral rivers of Dhaka with WHO standards in dotted lines (6.5–8.5). m m Figure 4. Max vs. Min Concentration of TDS for the peripheral rivers of Dhaka with WHO standards in dotted lines (1000 mg/L). m m Figures 5 and 6 represent Max vs. Min Concentrations of BOD5 and DO for all the peripheral rivers of Dhaka, respectively, with WHO standards in dotted lines. Testing of BOD5 is the best single test for evaluating organic contamination and has significant rele- vance in water quality evaluation [60]. The BOD5 ranged from 11 to 45 mg/L for the Dhaleshwari River samples, showing that the water is extremely contaminated (Figure 5). The observed BOD5 levels in the water samples indicated organic waste in the Dhaleshwari river [61]. Among the sampling stations, the highest BOD5 was found at Sam- pling station D-1 (Savar Tannery) (45 mg/L), while the lowest value was observed at Sam- pling station D-2 (Sudkhira) and D-4 (AKS dying) (11 mg/L) (Figure 5). BOD5 limits are 0.2 mg/L for drinking water, 3 mg/L for recreation, 6 mg/L for fish, and 10 mg/L for irri- gation [62]. Since the sampling stations run through the most heavily populated and in- Earth 2021, 2 703 dustrialized region along the riverbank, the BOD5 was greater along the selected stretch in Dhaleshwari than it was along the other stretches. Earth 2021, 2, FOR PEER REVIEW 8 m m m m Figure Figure 5.5. Max Max vs. vs. Min Min Concentration Concentration o of BOD f BO in Dthe 5 in peripheral the peripheral riversrive of Dhaka rs of Dh with aka wit WHOh WHO standar standards ds (5 mg/L). (5 mg/L). m m m m Figure Figure 6. 6 Max . Maxvs. vs. Min Min Concentration Concentration DO DO of peripheral of peripher rivers al of riv Dhaka ers of with Dhak WHO a with standar WHO stand ds ards (6 (6 m mg/L). g/L). The concentration of dissolved oxygen (DO) is a vital issue for aquatic organisms in Organic materials are also discharged along with the effluent as a result of poor-func- surface waters [8,63]. Low DO levels are indicative of the presence of oxygen-consuming tioning of the sewage treatment plants, storm discharges, agricultural slurries, domestic pollutants in the water body. The concentration of dissolved oxygen influences several waste (waste from humans and food) and industrial waste (food industries, tannery, and aspects of the water body (bacteria and photosynthesis), the availability and concentration dyeing) and silage liquor, thereby the Dhaleshwari River can accumulate various organic of nutrients [64]. The DO concentration among sampling stations along Dhaleshwari River ranged from 0.06 to 5.1 mg/L (Figure 6). The DO concentrations of all sampling stations and chemical pollutants. BOD5 levels varied within 33–49 mg/L for the Buriganga River, were deficient in the Dhaleshwari River. Sampling station D-1 exhibited the lowest value 30–39 mg/L for the Shitalakshya River, 32–49 mg/L for the Turag River, 27–39 mg/L for of DO (0.06 mg/L) beside the Savar tannery area. According to the Environmental Quality the Tongi Canal, and 15–38 mg/L for the Balu River (Figure 5). This reveals that the dis- Standard (EQS), the accompanying DO requirements are acceptable: fish and domesticated charge of organic substances and subsequent pollution is commonly happening in general animals require 4 to 6 milligrams per liter and 6 mg/L for drinking, 4 to 5 milligrams per for all the peripheral rivers at comparable rates. liter, whereas industrial applications require up to 5 milligrams per liter [50]. The The low con levels centra oftion dissolved of disso oxygen lved oxy could gen be(DO attributed ) is a vit to al the issue release forof aqu organic atic organisms in substances with high organic content, such as sewage treatment plants, storm flooding, surface waters [8,63]. Low DO levels are indicative of the presence of oxygen-consuming slurry cultivation, alcohol silage, etc. These low values of DO eventually impact the aquatic pollutants in the water body. The concentration of dissolved oxygen influences several species. By encouraging the growth of microorganisms in the water body, biodegradable aspects of the water body (bacteria and photosynthesis), the availability and concentration waste from industrial and residential sources causes a fast drop in DO value. All aquatic of nutrients [64]. The DO concentration among sampling stations along Dhaleshwari River species with aerobic respiratory biochemistry require oxygen to function [65]. When BOD ranged from 0.06 to 5.1 mg/L (Figure 6). The DO concentrations of all sampling stations levels are high, the amount of dissolved oxygen (DO) reduces because the bacteria absorb the were def oxygenicien obtained t in the Dh in the wate alershwar [65]. Consequ i River.ently Sampl , fish ing st and other ation D aquatic -1 exh species ibited t cannot he lowest value survive in oxygen-depleted conditions. Including the Dhaleshwari River as stated above, all of DO (0.06 mg/L) beside the Savar tannery area. According to the Environmental Quality the peripheral rivers of Dhaka were witnessed to have very low levels of dissolved oxygen, Standard (EQS), the accompanying DO requirements are acceptable: fish and domesti- ranging from 1.9–3.2 mg/L for the Buriganga River, 1.1–2.8 mg/L for the Shitalakshya River, cated animals require 4 to 6 milligrams per liter and 6 mg/L for drinking, 4 to 5 milligrams 0.6–1.2 mg/L for the Turag River, 3.4–4.4 mg/L for the Tongi Canal and 1.5–3.2 mg/L for per liter, whereas industrial applications require up to 5 milligrams per liter [50]. the Balu River (Figure 6). Almost all these ranges fall outside the required DO levels based The low levels of dissolved oxygen could be attributed to the release of organic sub- stances with high organic content, such as sewage treatment plants, storm flooding, slurry cultivation, alcohol silage, etc. These low values of DO eventually impact the aquatic spe- cies. By encouraging the growth of microorganisms in the water body, biodegradable waste from industrial and residential sources causes a fast drop in DO value. All aquatic species with aerobic respiratory biochemistry require oxygen to function [65]. When BOD5 levels are high, the amount of dissolved oxygen (DO) reduces because the bacteria absorb the oxygen obtained in the water [65]. Consequently, fish and other aquatic species cannot survive in oxygen-depleted conditions. Including the Dhaleshwari River as stated above, all the peripheral rivers of Dhaka were witnessed to have very low levels of dissolved oxygen, ranging from 1.9–3.2 mg/L for the Buriganga River, 1.1–2.8 mg/L for the Shita- lakshya River, 0.6–1.2 mg/L for the Turag River, 3.4–4.4 mg/L for the Tongi Canal and 1.5– 3.2 mg/L for the Balu River (Figure 6). Almost all these ranges fall outside the required DO levels based on the WHO guidelines (4–6 mg/L) (Figure 6). Figures 7 and 8 represent m m Max vs. Min Concentrations of TSS and COD respectively, for the peripheral rivers of Dhaka. Earth 2021, 2 704 Earth 2021, 2, FOR PEER REVIEW 9 m m Earth 2021, 2, FOR PEER REVIEW 9 on the WHO guidelines (4–6 mg/L) (Figure 6). Figures 7 and 8 represent Max vs. Min Concentrations of TSS and COD respectively, for the peripheral rivers of Dhaka. m m m m Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. m m Figure 7. Max vs. Min Concentration of TSS for the peripheral rivers of Dhaka for TSS. m m Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO m m m m Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO Figure 8. Max vs. Min Concentration of COD for the peripheral rivers of Dhaka for with WHO standards (10 mg/L). standards (10 mg/L). standards (10 mg/L). Total Total suspended suspended solids solids (TSS) (Tvalues SS) values in the in Dhaleshwari the Dhaleshw River ari varied River var from ied 191 from to 191 to 1278 Total suspended solids (TSS) values in the Dhaleshwari River varied from 191 to 1278 1278 mg/L (Figure 7). In studies involving sewage and other wastewater, the determination mg/L (Figure 7). In studies involving sewage and other wastewater, the determination of mg/L (Figure 7). In studies involving sewage and other wastewater, the determination of of suspended solids is especially useful and is as critical as the determination of BOD [61]. suspended solids is especially useful and is as critical as the determination of BOD5 [61]. suspended solids is especially useful and is as critical as the determination of BOD5 [61]. The presence of suspended solids in the canal is undesirable for causing putrefaction, and The presence of suspended solids in the canal is undesirable for causing putrefaction, and The presence of suspended solids in the canal is undesirable for causing putrefaction, and suspended particles can also contain many organic materials. The concentration levels of suspended particles can also contain many organic materials. The concentration levels of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment suspended particles can also contain many organic materials. The concentration levels of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of TSS were observed at high levels in all the peripheral rivers of Dhaka under assessment industrial waste and sewage to contamination and the quantity of oxygen required to (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of (Figure 7). Chemical oxygen demand (COD) is very useful in assessing the resistance of oxidize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari industrial waste and sewage to contamination and the quantity of oxygen required to ox- industrial waste and sewage to contamination and the quantity of oxygen required to ox- varied between 121.2 and 935 mg/L (Figure 8). In sampling station D-1, the highest COD idize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari idize organic and inorganic materials in a sample [66]. The COD levels in Dhaleshwari value was correlated with the flow of effluent from the dyeing unit that is released into varied between 121.2 and 935 mg/L (Figure 8). In sampling station D-1, the highest COD the vari river ed .bet The we higher en 12 levels 1.2 and of COD 935 mg/ in the L samples (Figure suggest 8). In sam an incr pling eased statio concentration n D-1, the of highest COD value was correlated with the flow of effluent from the dyeing unit that is released into industrial contaminants containing inorganic and organic compounds, thereby indicating value was correlated with the flow of effluent from the dyeing unit that is released into ath higher e river. degr Th eeeof higher toxicity leve [67,ls 68]. of COD COD values in thranged e samp frles om su 170–1400 ggest an mg/L incr for eathe sed Turag concentration of the river. The higher levels of COD in the samples suggest an increased concentration of River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, industrial contaminants containing inorganic and organic compounds, thereby indicating industrial contaminants containing inorganic and organic compounds, thereby indicating 180.2–321.49 mg/L for the Balu River, and 302.1–402.1 mg/L for the Shitalakshya River, a higher degree of toxicity [67,68]. COD values ranged from 170–1400 mg/L for the Turag a higher degree of toxicity [67,68]. COD values ranged from 170–1400 mg/L for the Turag suggesting a high level of contamination in these rivers based on the WHO guideline River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, River, 182.2–302.4 mg/L for the Tongi Canal, 390.1–882.2 mg/L for the Buriganga River, (10 mg/L) (Figure 8). 180.2–321.49 mg/L for the Balu River, and 302.1–402.1 mg/L for the Shitalakshya River, m m 180.2 Figur –32e 1.49 9 repr mg/ esents L for Max the vs. Balu Min River Concentrations , and 302.1–of 402.1 EC for mg/ the L peripheral for the Shi rivers talakshya River, suggesting a high level of contamination in these rivers based on the WHO guideline (10 of Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) suggesting a high level of contamination in these rivers based on the WHO guideline (10 varied mg/L) fr( om Fig286.1 ure 8). to 5309.6 S/cm in the Dhaleshwari River (Figure 9). According to the mg/L) (Figure 8). m m WHO standards, a water body with an EC of more than 1000 mg/L is not suitable for Figure 9 represents Max vs. Min Concentrations of EC for the peripheral rivers of m m Figure 9 represents Max vs. Min Concentrations of EC for the peripheral rivers of the agricultural sector, domestic, bathing, industrial, or drinking purposes. Among the Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) var- Dhaka while WHO standards are shown in dotted lines. Electrical conductivity (EC) var- ied from 286.1 to 5309.6 μS/cm in the Dhaleshwari River (Figure 9). According to the WHO ied from 286.1 to 5309.6 μS/cm in the Dhaleshwari River (Figure 9). According to the WHO standards, a water body with an EC of more than 1000 mg/L is not suitable for the agri- standards, a water body with an EC of more than 1000 mg/L is not suitable for the agri- cultural sector, domestic, bathing, industrial, or drinking purposes. Among the five sam- cultural sector, domestic, bathing, industrial, or drinking purposes. Among the five sam- pling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 pling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 μS/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 μS/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 μS/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed μS/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed WHO guidelines (1000 μS/cm) for the permissible limit of EC. Emissions from tanneries WHO guidelines (1000 μS/cm) for the permissible limit of EC. Emissions from tanneries and metal plating industries might be responsible for the increase in electrical conductiv- and metal plating industries might be responsible for the increase in electrical conductiv- ity. Industries like textile and dyeing generate heavy metals as well. There may be some ity. Industries like textile and dyeing generate heavy metals as well. There may be some physiological effects of high EC levels on plants and some of the environmental species. physiological effects of high EC levels on plants and some of the environmental species. Earth 2021, 2 705 five sampling stations, the highest EC was found at Sampling station D-1 (Savar tannery) (5309.6 S/cm), while the lowest value was found at Sampling station D-2 (Sudkhira) (286.1 S/cm). Sampling stations D-1 (Savar Tannery) and D-3 (Dhalla, fish market) exceed Earth 2021, 2, FOR PEER REVIEW 10 WHO guidelines (1000 S/cm) for the permissible limit of EC. Emissions from tanneries and metal plating industries might be responsible for the increase in electrical conductivity. Industries like textile and dyeing generate heavy metals as well. There may be some physiological effects of high EC levels on plants and some of the environmental species. However, these concentrations suggest that wastewater (industrial and sewage effluent) However, these concentrations suggest that wastewater (industrial and sewage effluent) containing high ionic concentrations get discharged into the rivers, ultimately causing containing high ionic concentrations get discharged into the rivers, ultimately causing detrimental effects to the aquatic biodiversity. With respect to the other peripheral rivers, detrimental effects to the aquatic biodiversity. With respect to the other peripheral rivers, EC varied from 890 to 1120 µ S/cm for the Turag River, 1100 to 1400 µ S/cm for the Tongi EC varied from 890 to 1120 S/cm for the Turag River, 1100 to 1400 S/cm for the Tongi Canal, 10 to 1390 µ S/cm for the Buriganga River, 220 to 1400 µ S/cm for the Shitalakhya Canal, 10 to 1390 S/cm for the Buriganga River, 220 to 1400 S/cm for the Shitalakhya River River , and , an210 d 21 to0 1300 to 1300 S/cm µ Sf /c or m the for Balu the River Balu . Based River. on Ba WHO sed on criteria, WHO these criteri rivers a, th have ese rivers have significant levels of ionic pollution (Figure 9). significant levels of ionic pollution (Figure 9). m m m m Figure 9. Max vs. Min Concentration of EC for the peripheral rivers of Dhaka for with WHO Figure 9. Max vs. Min Concentration of EC for the peripheral rivers of Dhaka for with WHO standar standard in d d in dotted otted line l(1000 ine (1000 S/cm). μS/cm). 3.2. Correlation among the Physicochemical Parameters of Dhaleshwari River 3.2. Correlation among the Physicochemical Parameters of Dhaleshwari River The correlation coefficient represents the relations among the variables and the assess- The correlation coefficient represents the relations among the variables and the as- ment of whether a specific variable depends on the other variables or not. Correlations among sessmen thet physicochemical of whether a spec parameters ific variof abl analyzed e depenwater ds on samples the other from variable the Dhaleshwari s or not. Correlations River were obtained using Pearson’s correlation and linear regression analysis in order among the physicochemical parameters of analyzed water samples from the Dhaleshwari to determine their interrelationships [61]. The correlation matrix among different water River were obtained using Pearson’s correlation and linear regression analysis in order to quality parameters of the Dhaleshwari River is presented in Table 4. The correlation coeffi- determine their interrelationships [61]. The correlation matrix among different water cient ranges between 1 and +1. Between 0.5 and 0.8, the relationship could be considered quality parameters of the Dhaleshwari River is presented in Table 4. The correlation coef- moderate, and above 0.8, the association could be considered substantial [69]. ficient ranges between −1 and +1. Between 0.5 and 0.8, the relationship could be consid- Table 4. Pearson’s correlation coefficients among the physicochemical parameters in the Dhaleshwari ered moderate, and above 0.8, the association could be considered substantial [69]. River (significance of correlation was measured both at 0.01 and 05 levels). Table 4. Pearson’s correlation coefficients among the physicochemical parameters in the Parameters pH TSS TDS BOD COD DO EC Dhaleshwari River (significance of correlation was measured both at 0.01 and 05 levels). pH 1 TSS 0.888 * 1 Parame- TDS 0.821 0.773 * 1 pH TSS TDS BOD5 COD DO EC ters BOD 0.550 0.590 0.547 1 COD 0.726 0.735 0.756 0.960 ** 1 pH 1 DO 0.517 0.796 0.452 0.783 0.766 1 TSS 0.888 * 1 EC 0.541 0.695 0.879 * 0.570 0.718 0.613 1 TDS 0.821 0.773 * 1 * Correlation is significant at the 0.05 level (2-tailed); ** Correlation is significant at the 0.01 level (2-tailed). BOD5 0.550 0.590 0.547 1 COD 0.726 0.735 0.756 0.960 ** 1 This investigation demonstrated that pH has significant strong positive correlations DO −0.517 −0.796 −0.452 −0.783 −0.766 1 (p < 0.01) with TSS and TDS (r = 0.888 and 0.821). It was also observed that DO has strong EC 0.541 0.695 0.879 * 0.570 0.718 −0.613 1 * Correlation is significant at the 0.05 level (2-tailed); ** Correlation is significant at the 0.01 level (2-tailed). This investigation demonstrated that pH has significant strong positive correlations (p < 0.01) with TSS and TDS (r = 0.888 and 0.821). It was also observed that DO has strong negative correlations with pH, TSS, TDS, BOD5, COD and EC (r = −0.517, −0.796, −0.452, −0.783, −0.766 and −0.613, respectively). The photosynthetic activity of algae, water tem- perature, aquatic respiration, oxidative degradation of organic materials, etc., impact pH and DO fluctuations [69]. It is also clear from the results that the TDS was moderately correlated with TSS, BOD5, COD, and EC (r = 0.773, 0.547, 0.756, 0.879 respectively) (Table 4). In water, this implies the presence of dissolved materials (organic matter and salts) Earth 2021, 2 706 negative correlations with pH, TSS, TDS, BOD , COD and EC (r = 0.517, 0.796, 0.452, 0.783, 0.766 and 0.613, respectively). The photosynthetic activity of algae, water temperature, aquatic respiration, oxidative degradation of organic materials, etc., impact pH and DO fluctuations [69]. It is also clear from the results that the TDS was moderately correlated with TSS, BOD , COD, and EC (r = 0.773, 0.547, 0.756, 0.879 respectively) (Table 4). In water, this implies the presence of dissolved materials (organic matter and salts) [70]. DO was shown to be negatively associated with all factors and not substantially connected with any of the examined parameters by Usharani et al. [61]. COD was found to have strong positive correlations (p < 0.01) with BOD (r = 0.960). EC was observed to possess significant positive correlation (p < 0.01) with pH, TSS, TDS, BOD , and COD respectively (r = 0.541, 0.695, 0.879, 0.570 and 0.718, respectively) and negatively correlated with DO (r = 0.613). It is also evident from these observations that the aquatic body is severely contaminated due to the different forms of industrial waste that are dumped directly into the water body. 3.3. Comparative Assessment of Heavy Metal Contamination Table 5 shows the concentrations of heavy metals in the Dhaleshwari River analyzed in the present study. This table also lists the heavy metal levels in the other peripheral rivers of Dhaka city that were reported by previous studies. Surface water standards by WHO and FAO are provided in the table as well. The average concentration levels of the analyzed heavy metals followed a decreasing order of Cr > Ni > Cd > Zn in the river water. The concentration of chromium in water varied from 0.08 to 0.92 mg/L in Dhaleshwari River, which might be due to the extensive disposal of domestic sewage and runoff from agricultural zone [22,24]. Table 5. Heavy Metals Concentration (mg/L) levels of the water samples of the Dhaleshwari River and the other peripheral rivers in Dhaka city. Average  Standard Error of Mean References Cd Cr Ni Zn Dhaleshwari River 0.19  0.01 0.71  0.16 0.62  0.1 0.18  0.03 Present Study Buriganga River 0.015  0.003 2.04  1.53 0.19  0.03 0.21  0.04 [70] Shitalakshya River 0.011  0.003 - - 0.0263  0.003 [71] Turag River - 0.32  0.02 0.018  0.003 0.10  0.01 [55] Tongi Canal - 0.01 0.005 0.156 [72] Balu River 0.01  0.001 - - 0.03  0.002 [71] WHO 0.003 0.05 0.05 3 [73] 0.01 0.1 0.2 2 [74] FAO a b WHO = World Health Organization; FAO = Food and Agriculture Organization. m m Figures 10 and 11 represent the Max vs Min Concentrations of the heavy metals Cd and Cr, respectively for all the peripheral rivers of Dhaka. The figures also show the WHO standards in dotted lines. The highest contamination of Cd was recorded at sampling location D-1 (0.25 mg/L), resulting from the Savar tannery industries zone, and the lowest amount was recorded at sampling location D-2 (Sudkhira) (0.15 mg/L) in the Dhaleshwari River (Figure 11). The results exceeded the allowable limits specified by World Health Organization (0.003 mg/L, Food and Agriculture Organization (0.01 mg/L), and The Environmental Conservation Rules (0.005 mg/L) [72–75]. Table 5 shows that Arefin et al. [55] recorded Cr at 0.32 mg/L in the Turag River, and Biswas et al. [72] found Cr at 0.01 mg/L in the Tongi Canal. The present study observed the highest chromium concentration at 7.76 mg/L in the Buriganga River [70] among the peripheral rivers (Figure 11), which may result from the operation and maintenance of various cooling towers at different industries beside Buriganga. Chromium-containing compounds from cooling towers might have been discharged into the Buriganga River. Although the selected section of the Dhaleswari river is located near the Savar tannery effluent discharge region, Earth 2021, 2 707 Earth 2021, 2, FOR PEER REVIEW 12 Earth 2021, 2, FOR PEER REVIEW 12 the concentration of Cr at this site is lower than that in Buriganga, however, exceeding the permissible level. Since water cotyledons (E. crassipes) were growing surrounding the sample site throughout the sampling period, these water cotyledons are believed to sample site throughout the sampling period, these water cotyledons are believed to accu- sample site throughout the sampling period, these water cotyledons are believed to accu- accumulate Cr and are termed chrome-sorbent plants [76,77]. mulate Cr and are termed chrome-sorbent plants [76,77]. mulate Cr and are termed chrome-sorbent plants [76,77]. Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted Figure 10. Concentrations for Cd in the peripheral rivers of Dhaka with WHO standard in dotted line line (0 (0.003 .003 mg/L). mg/L). line (0.003 mg/L). Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted Figure 11. Concentrations for Cr in the peripheral rivers of Dhaka with WHO standard in dotted line line (0.05 mg/L). line (0.05 mg/L). (0.05 mg/L). In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along In the Dhaleshwari River, Cd (cadmium) values varied from 0.15 to 0.25 mg/L along the five sampling locations. Figure 10 shows that the concentration of Cd is above the the five sampling locations. Figure 10 shows that the concentration of Cd is above the the five sampling locations. Figure 10 shows that the concentration of Cd is above the tolerable limit specified by World Health Organization (WHO) and Food and Agricul- tolerable limit specified by World Health Organization (WHO) and Food and Agriculture tolerable limit specified by World Health Organization (WHO) and Food and Agriculture ture Organization (FAO) (0.003 mg/L and 0.01 mg/L, respectively) [73,74]. Potential Organization (FAO) (0.003 mg/L and 0.01 mg/L, respectively) [73,74]. Potential sources of sour Organ ces ization of cadmium (FAO in) the (0.00 Dhaleshwari 3 mg/L and River 0.01 m include g/L, r batteries, espectively pigment ) [73s, ,7and 4]. Poten plating tial sources of cadmium in the Dhaleshwari River include batteries, pigments, and plating businesses businesses [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may cadmium in the Dhaleshwari River include batteries, pigments, and plating businesses [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may be caused be caused by effluents from the Savar tannery industries, is higher than WHO allowable [37,70]. The highest Cr concentration observed at D-1 (0.92 mg/L), which may be caused limit (0.05 mg/L). Apart from this, every sampling station around the industrial sector of by effluents from the Savar tannery industries, is higher than WHO allowable limit (0.05 by effluents from the Savar tannery industries, is higher than WHO allowable limit (0.05 Savar city has a Cr content over the permissible limit. Cadmium exposure for a prolonged mg/L). Apart from this, every sampling station around the industrial sector of Savar city mg/L). Apart from this, every sampling station around the industrial sector of Savar city period over the permissible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] has a Cr content over the permissible limit. Cadmium exposure for a prolonged period has a Cr content over the permissible limit. Cadmium exposure for a prolonged period reported that red tilapia mortality was caused in Alexandria, Egypt, through exposure to over the permissible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] reported very over high the levels permof iss cadmium. ible limit could cause allergic dermatitis [78]. El-Ebiary et al. [79] reported that red tilapia mortality was caused in Alexandria, Egypt, through exposure to very high Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for that red tilapia mortality was caused in Alexandria, Egypt, through exposure to very high water levels of ca samples dmium. for the Shitalakshya River by Mokaddes et al. [71] and 0.015 mg/L for levels of cadmium. the Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for Table 5 shows that average (arithmetic means) of Ni was found at 0.011 mg/L for current study was obtained at a much lower concentration than the water quality standard water samples for the Shitalakshya River by Mokaddes et al. [71] and 0.015 mg/L for the water samples for the Shitalakshya Ri m ver by m Mokaddes et al. [71] and 0.015 mg/L for the limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the cur- Buriganga River by Sarkar et al. [70]. However, the concentration of cadmium in the cur- of Dhaka for Ni and Zn, respectively, while the WHO standards are shown in dotted lines. rent study was obtained at a much lower concentration than the water quality standard The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 rent study was obtained at a much lower concentration than the water quality standard m m limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers to 0.87 mg/L (Figure 12). Every sample location exceeded m Ni m concentrations according limit [80]. Figures 12 and 13 represent Max vs. Min concentrations of peripheral rivers to of WHO Dhaka permitted for Ni and limit Zn (0.1 , re mg/L). spectively, Nickel wis hil ae car thcinogenic e WHO stand metalar that ds leads are shown to sever in e dotted lines. of Dhaka for Ni and Zn, respectively, while the WHO standards are shown in dotted lines. The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 to The concentration of nickel (Ni) in the water of the Dhaleshwari River varied from 0.33 to 0.87 mg/L (Figure 12). Every sample location exceeded Ni concentrations according to 0.87 mg/L (Figure 12). Every sample location exceeded Ni concentrations according to WHO permitted limit (0.1 mg/L). Nickel is a carcinogenic metal that leads to severe dam- WHO permitted limit (0.1 mg/L). Nickel is a carcinogenic metal that leads to severe dam- age to the liver and heart, reduced body weight, and skin irritation due to long-term ex- age to the liver and heart, reduced body weight, and skin irritation due to long-term ex- posure [81]. posure [81]. Earth 2021, 2 708 Earth 2021, 2, FOR PEER REVIEW  13  Earth 2021, 2, FOR PEER REVIEW  13  damage to the liver and heart, reduced body weight, and skin irritation due to long-term exposure [81]. Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted line Figure 12. Concentrations for Ni in the peripheral rivers of Dhaka with WHO standard in dotted  line (0.003 mg/L).  (0.003 mg/L). line (0.003 mg/L).  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted  Figure 13. Concentrations for Zn in the peripheral rivers of Dhaka with WHO standard in dotted line (3 mg/L).  line (3 mg/L). line (3 mg/L).  Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in  Table 5 shows that average (arithmetic mean) level of Ni was found at 0.19 mg/L in  the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag  the Buriganga River by Sarkar et al. [70], 0.018 mg/L was recorded upstream of the Turag  River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas et  River by Islam et al. [82], and 0.005 mg/L of Ni was recorded in Tongi Canal by Biswas et  et al. [72]. Several dockyards were established beside the Buriganga Riverbank, and a few al. [72]. Several dockyards were established beside the Buriganga Riverbank, and a few  launch al. [72] stations . Severar ale doc located kyanear rds were the station  estab [l 70 ished ]. Nickel  beside concentrations  the Buriga inng the a Riverb Buriganga ank, and a few  launch stations are located near the station [70]. Nickel concentrations in the Buriganga  River might result from several factors relating to discharge from specific manufacturing launch stations are located near the station [70]. Nickel concentrations in the Buriganga  industries. Ni has been associated with cancer, lung damage, and dermatitis, among other River might result from several factors relating to discharge from specific manufacturing  River might result from several factors relating to discharge from specific manufacturing  health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari industries. Ni has been associated with cancer, lung damage, and dermatitis, among other  industries. Ni has been associated with cancer, lung damage, and dermatitis, among other  River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO , health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari  health problems [83]. Zinc contamination at various sampling stations in the Dhaleshwari  which might explain why surface water has a lower percentage of Zn than deep water does, River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO3,  River water varied from 0.09 to 0.29 mg/L (Figure 13). Zn could be precipitated as ZnCO3,  according to previous researchers [84]. The contamination of Zn was within the acceptable which might explain why surface water has a lower percentage of Zn than deep water  limit by WHO (3 mg/L) in all the peripheral rivers. which might explain why surface water has a lower percentage of Zn than deep water  does, according to previous researchers [84]. The contamination of Zn was within the ac‐ does, according to previous researchers [84]. The contamination of Zn was within the ac‐ 3.4. Correlation among the Heavy Metals in Dhaleshwari River ceptable limit by WHO (3 mg/L) in all the peripheral rivers.  ceptable limit by WHO (3 mg/L) in all the peripheral rivers.  The Pearson’s correlation matrix among the different trace metals for Dhaleshwari River is presented in Table 6. The majority of heavy metals showing a significantly linear 3.4. Correlation among the Heavy Metals in Dhaleshwari River  3.4. Correlation among the Heavy Metals in Dhaleshwari River  dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni The Pearson’s correlation matrix among the different trace metals for Dhaleshwari  and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719). The Pearson’s correlation matrix among the different trace metals for Dhaleshwari  River is presented in Table 6. The majority of heavy metals showing a significantly linear  This is because runoff from agricultural land, leather industries, and tanneries located in River is presented in Table 6. The majority of heavy metals showing a significantly linear  Savar city are constantly contributing untreated sewage and solid waste in the Dhaleshwari dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni  dependence among them. A strong correlation emerged between Cr and Cd (r = 0.639), Ni  River, leading to an increased concentration of each of the metals. Tannery wastewater, and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719).  and Cd (r = 0.627), Ni and Cr (r = 0.663), Zn and Cd (r = 0.919) and Zn and Cr (r = 0.719).  including residues from the tanning, re-tanning, and basification phases of leather manu- This is because runoff from agricultural land, leather industries, and tanneries located in  This is because runoff from agricultural land, leather industries, and tanneries located in  facturing, as well as municipal sewerage, are included in this category. It is utilized to allow Savar  city  are  constantly  contributing  untreated  sewage  and  solid  waste  in  the  the Sav chr aromium   city  or are aldehyde   constato ntly attach   contributin to the sking pr  otein untrea during ted  the sew tanning age  an prd ocess   solid [84 ].waste  in  the  Dhaleshwari River, leading to an increased concentration of each of the metals. Tannery  Dhaleshwari River, leading to an increased concentration of each of the metals. Tannery  wastewater, including residues from the tanning, re‐tanning, and basification phases of  wastewater, including residues from the tanning, re‐tanning, and basification phases of  leather manufacturing, as well as municipal sewerage, are included in this category. It is  leather manufacturing, as well as municipal sewerage, are included in this category. It is  utilized to allow the chromium or aldehyde to attach to the skin protein during the tan‐ utilized to allow the chromium or aldehyde to attach to the skin protein during the tan‐ ning process [84].  ning process [84].          Earth 2021, 2 709 Table 6. Pearson’s Correlation matrix among the Heavy Metals in the Dhaleshwari River (significance of correlation was measured both at 0.05 levels). Parameters Cd Cr Ni Zn Cd 1 Cr 0.639 * 1 Ni 0.627 * 0.663 * 1 Zn 0.919 * 0.719 * 0.446 1 * Correlation is significant at the 0.05 level (2-tailed). 3.5. Ecological Risk Assessment A technique for assessing ecological hazards with relation to water pollution reduction was devised by Hakanson [54]. The ecological risk indices of individual metals for all the peripheral rivers have been estimated, which are presented in Table 7. The measured values of the ecological risk index (E ) for heavy metals show a descending trend along with the RI locations of Dhaleshwari River as follows: D-1 > D-4 > D-5> D-3> D-2. The calculated E RI values ranged from 469.71 to 830.32, with an average of 623.47 in Dhaleshwari River. The lower value was observed at D-2, representing the Sudkhira area while the highest value was observed in the D-1 location (Savar tannery area). This may be due to the tannery activities, which also indicate a high degree of ecological risk. Every sampling station was contributed by leather and dying industries. According to Table 7, sampling stations D-1 (Savar tannery), D-2 (Sudkhira), D-3 (Dhalla, fish market), D-4 (AKS dying), and D-5 (Nama Bazar) showed E values greater than 300, all of which are indicating a disastrous RI degree of ecological risk. The ecological risk index was very low (E < 100), indicating low RI risk in the Shitalakshya River, Turag River, and Tongi Canal. Table 7. Ecological risk characterization of the Peripheral Rivers in Dhaka city. a i Sampling Station E Risk Grade RI Cd Cr Ni Zn D-1 750 36.8 43.5 0.02 830.32 Disastrous risk D-2 450 3.2 16.5 0.006 469.71 Disastrous risk D-3 510 31.2 36.5 0.007 577.71 Disastrous risk D-4 570 35.6 19.5 0.015 625.11 Disastrous risk D-5 540 36 38.5 0.012 614.51 Disastrous risk Buriganga River 59.4 310.62 10.35 0.02 380.39 Disastrous risk Shitalakshya River 36 - - 0.002 36.002 Low risk Turag River - 10 1.4 0.013 11.413 Low risk Tongi Canal - 0.4 0.25 0.01 0. 66 Low risk a i b E = Ecological risk factor; E = Ecological risk index. RI It is worth mentioning that these higher values of E might be attributed to the RI presence of greater degrees of Cd at each sampling station. Phosphate fertilizers, non- ferrous metal mining or refining, and waste disposal are among the anthropogenic (result of human activity) sources of cadmium in the environment [85]. A vast amount of agricultural land and metal processing industries exist around the Dhaleshwari River. Extra cadmium accumulates in the aquatic organism and crops. Untreated waste from tanneries, unplanned urbanization, raw effluent from several dying industries, leather waste throughout the selected stretch are the plausible causes of the disastrous ecological risk. The Ecological risk indices for the other peripheral rivers were also evaluated with the information gathered from different studies [71–73,86,87] and presented in Table 7. Authors obtained an ecological risk at a level of 380.39 in the surface water of the Buriganga River according to the concentration levels reported by Sarkar et al. (2015), which also indicates disastrous level of risk in the Buriganga. However, based on the characterization by Ecological Risk Index, all the other rivers (Turag, Tongi Canal and Shitalakshya) exhibited low level of Earth 2021, 2 710 risks. Thus ecosystems are severely under threat in the Dhaleshwari and Buriganga rivers while the other rivers could maintain ecosystem without significant threat. 4. Conclusions The present study dealt with evaluating the current water quality of the Dhaleshwari river in terms of physicochemical parameters and heavy metals while the study also attempted to make a comparative assessment on pollution status among all the peripheral rivers around Dhaka City. Significant contamination was observed at every peripheral river concerning identified parameters such as dissolved oxygen (DO), total dissolved solids (TDS), 5-day biochemical oxygen demand (BOD ) and chemical oxygen demand (COD). This study also performed investigation on the status of relevant heavy metals (chromium-Cr, cadmium-Cd, nickel-Ni, zinc-Zn) pollution in different rivers of Dhaka City. The concentration levels of the toxic metals such as Cr, Cd, and Ni in the Savar tannery (D-1), Sudkhira (D-2), AKS dying (D-4), and Nama Bazar (D-5) areas of Dhaleshwari River and Buriganga river in general seemed to be of significant and of high concern warranting regular and detailed investigation and monitoring. Heavy metals pollution was further characterized in this study by ecological risk index (E ). Except for the Burganga and Dhaleshwari rivers, the ecological risk index values RI showed very low levels (E < 100) for the Shitalakshya River, Turag River, and Tongi Canal, RI indicating lower level of risk. However, the ecological risk index measured contamination intensity of heavy metals that revealed disastrous risk (E  300) at sampling stations RI D-1 (Savar tannery), D-2 (Sudkhira), D-3 (Dhalla, fish market), D-4 (AKS dying), and D-5 (Nama Bazar) in the Dhaleshwari River and disastrous level of ecological risk was also obtained in the Buriganga River. Based on all the physicochemical and toxicity-based risk characterization, the river system in Dhaka city can be termed as severely polluted based on organic and solids discharge whilst not all the rivers could be considered as significant threats to maintain ecosystems in general, except for the Dhaleshwari and Burganga rivers. A wider level and continuous comprehensive investigation will be required to confirm on the ecological characterization of the rivers. Although, it was observed that the deviation of physicochemical parameters for certain peripheral rivers of Dhaka were not significant enough from the standards, however, satisfactory conditions are yet to be expected. Furthermore, after the relocation of Hazaribagh tannery to Savar, the water quality of the Dhaleshwari river started to deteriorate and quite possibly could pose a severe threat to the ecosystem. If appropriate measures are not adopted soon enough, this will impact both the ecological and public health around the river. On the context of ever-increasing industrial growth and urbanization concerns in Dhaka city, present findings lay down additional foundation for frequent monitoring of the river systems and their tributaries. As part of the steps to abate the water pollution for river system of Dhaka City, a continual assessment of waste discharge and pollutant loadings is warranted on a regular basis. Author Contributions: Conceptualization, M.A.S.I. and N.M.; Investigation, M.A.S.I. and N.M.; Data Collection and Analysis, M.A.S.I. and M.E.H.; Investigation; M.A.S.I., M.E.H. and N.M.; Writing— original draft preparation, M.A.S.I.; Writing—review and editing, M.A.S.I. and N.M.; Supervision; N.M. and M.E.H. All authors have read and agreed to the published version of the manuscript. Funding: This work was supported by the Undergraduate Thesis fund of the Department of Civil Engineering, University of Asia Pacific, Dhaka, Bangladesh. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Acknowledgments: The authors hereby declare that the work was part of undergraduate thesis work with support from Department of Civil Engineering at University of Asia Pacific and the Department Earth 2021, 2 711 of Soil, Water and Environment at Dhaka University in collaboration. No additional funding was received for performing any part of this study. Conflicts of Interest: The authors declare that they have no conflict of interest. References 1. Roy, S.; Banna, L.; Hossain, M.; Rahman, H. Water quality of Narai canal and Balu river of Dhaka City: An impact of industrial- ization. J. Bangladesh Agric. Univ. 2014, 12, 285–290. [CrossRef] 2. Sener ¸ , S.; ¸ Se ¸ ner, E.; Davraz, A. Evaluation of water quality using water quality index (WQI) method and GIS in Aksu River (SW-Turkey). Sci. Total. Environ. 2017, 584, 131–144. [CrossRef] 3. Mustafa, M.; Brooks, A.C. A comparative study of two seasonal floodplain aquaculture systems in Bangladesh. Water Policy 2009, 11, 69–79. [CrossRef] 4. Islam, F.; Rahman, M.; Khan, S.; Ahmed, B.; Bakar, A.; Halder, M. Heavy metals in water, sediment and some fishes of Karnofuly River, Bangladesh. Pollut. Res. 2013, 32, 715–721. 5. Hafizur, R.; Nuralam, H.; Rumainul, I. Investigation of physicochemical parameter, heavy metal in Turag river water and adjacent industrial effluent in Bangladesh. J. Sci. Technol. Environ. Inform. 2017, 5, 347–360. [CrossRef] 6. Karn, S.K.; Harada, H. Surface water pollution in three urban territories of Nepal, India, and Bangladesh. Environ. Manag. 2001, 28, 483–496. 7. Haigh, M.J. Sustainable management of headwater resources: The Nairobi’Headwater ’Declaration (2002) and beyond. Asian J. Water Environ. Pollut. 2004, 1, 17–28. 8. Kumar, R.N. An assessment of seasonal variation and water quality index of Sabarmati River and Kharicut canal at Ahmedabad, Gujarat. Electron. J. Environ. Agric. Food Chem. 2011, 10, 2248–2261. 9. Hacioglu, N.; Dulger, B. Monthly variation of some physico-chemical and microbiological parameters in Biga Stream (Biga, Canakkale, Turkey). Afr. J. Biotechnol. 2009, 8, 1929–1937. 10. Alam, M.M.; Islam, M.A.; Islam, S.; Haider, S.Z. Surface water quality of various polluted locations. J. Bangladesh Chem. Soc. 1996, 8, 129–137. [CrossRef] 11. Raknuzzaman, M.; Ahmed, M.K.; Islam, M.S.; Habibullah-Al-Mamun, M.; Tokumura, M.; Sekine, M.; Masunaga, S. Trace metal contamination in commercial fish and crustaceans collected from coastal area of Bangladesh and health risk assessment. Environ. Sci. Pollut. Res. 2016, 23, 17298–17310. [CrossRef] 12. Ahsan, M.A.; Siddique, M.A.B.; Munni, M.A.; Akbor, M.A.; Akter, S.; Mia, M.Y. Analysis of physicochemical parameters, anions and major heavy metals of the Dhaleshwari River water, Tangail, Bangladesh. Am. J. Environ. Prot. 2018, 7, 29–39. [CrossRef] 13. Ahmed, M.K.; Ahamed, S.; Rahman, S.; Haque, M.R.; Islam, M.M. Heavy metals concentration in water, sediments and their bioaccumulation in some freshwater fishes and mussel in Dhaleshwari River, Bangladesh. Terr. Aquat. Environ. Toxicol. 2009, 3, 33–41. 14. Mohanta, L.C.; Niloy, M.N.H.; Chowdhury, G.W.; Islam, D.; Lipy, E.P. Heavy metals in water, sediment and three fish species of Dhaleshwari river, Savar. Bangladesh J. Zool. 2019, 47, 263–272. [CrossRef] 15. Biplob, P.; Fatihah, S.; Shahrom, Z.; Ahmed, E. Nitrogen-removal efficiency in an upflow partially packed biological aerated filter (BAF) without backwashing process. J. Water Reuse Desalination 2011, 1, 27–35. [CrossRef] 16. Zetterberg, C.; Öfverholm, T. Carpal tunnel syndrome and other wrist/hand symptoms and signs in male and female car assembly workers. Int. J. Ind. Ergon. 1999, 23, 193–204. [CrossRef] 17. Doyle, M.P.; Herman, J.G.; Dykstra, R.L. Autocatalytic oxidation of hemoglobin induced by nitrite: Activation and chemical inhibition. J. Free. Radic. Biol. Med. 1985, 1, 145–153. [CrossRef] 18. Yuan, G.-L.; Liu, C.; Chen, L.; Yang, Z. Inputting history of heavy metals into the inland lake recorded in sediment profiles: Poyang Lake in China. J. Hazard. Mater. 2011, 185, 336–345. [CrossRef] 19. Armitage, P.D.; Bowes, M.J.; Vincent, H.M. Long-term changes in macroinvertebrate communities of a heavy metal polluted stream: The river Nent (Cumbria, UK) after 28 years. River Res. Appl. 2007, 23, 997–1015. [CrossRef] 20. Sin, S.; Chua, H.; Lo, W.; Ng, L. Assessment of heavy metal cations in sediments of Shing Mun River, Hong Kong. Environ. Int. 2001, 26, 297–301. [CrossRef] 21. Srebotnjak, T.; Carr, G.; de Sherbinin, A.; Rickwood, C. A global Water Quality Index and hot-deck imputation of missing data. Ecol. Indic. 2012, 17, 108–119. [CrossRef] 22. Islam, M.S.; Han, S.; AHMED, M.K.; Masunaga, S. Assessment of trace metal contamination in water and sediment of some rivers in Bangladesh. J. Water Environ. Technol. 2014, 12, 109–121. [CrossRef] 23. Su, S.; Xiao, R.; Mi, X.; Xu, X.; Zhang, Z.; Wu, J. Spatial determinants of hazardous chemicals in surface water of Qiantang River, China. Ecol. Indic. 2013, 24, 375–381. [CrossRef] 24. Koukal, B.; Dominik, J.; Vignati, D.; Arpagaus, P.; Santiago, S.; Ouddane, B.; Benaabidate, L. Assessment of water quality and toxicity of polluted Rivers Fez and Sebou in the region of Fez (Morocco). Environ. Pollut. 2004, 131, 163–172. [CrossRef] [PubMed] 25. Cataldo, D.; Colombo, J.; Boltovskoy, D.; Bilos, C.; Landoni, P. Environmental toxicity assessment in the Paraná river delta (Argentina): Simultaneous evaluation of selected pollutants and mortality rates of Corbicula fluminea (Bivalvia) early juveniles. Environ. Pollut. 2001, 112, 379–389. [CrossRef] Earth 2021, 2 712 26. Mohiuddin, K.; Zakir, H.; Otomo, K.; Sharmin, S.; Shikazono, N. Geochemical distribution of trace metal pollutants in water and sediments of downstream of an urban river. Int. J. Environ. Sci. Technol. 2010, 7, 17–28. [CrossRef] 27. Hobbelen, P.; Koolhaas, J.; Van Gestel, C. Risk assessment of heavy metal pollution for detritivores in floodplain soils in the Biesbosch, The Netherlands, taking bioavailability into account. Environ. Pollut. 2004, 129, 409–419. [CrossRef] [PubMed] 28. Harikumar, P.; Nasir, U.; Rahman, M.M. Distribution of heavy metals in the core sediments of a tropical wetland system. Int. J. Environ. Sci. Technol. 2009, 6, 225–232. [CrossRef] 29. Miller, C.V.; Foster, G.D.; Majedi, B.F. Baseflow and stormflow metal fluxes from two small agricultural catchments in the Coastal Plain of the Chesapeake Bay Basin, United States. Appl. Geochem. 2003, 18, 483–501. [CrossRef] 30. Dassenakis, M.; Scoullos, M.; Foufa, E.; Krasakopoulou, E.; Pavlidou, A.; Kloukiniotou, M. Effects of multiple source pollution on a small Mediterranean river. Appl. Geochem. 1998, 13, 197–211. [CrossRef] 31. Abdel-Ghani, N.; Elchaghaby, G. Influence of operating conditions on the removal of Cu, Zn, Cd and Pb ions from wastewater by adsorption. Int. J. Environ. Sci. Technol. 2007, 4, 451–456. [CrossRef] 32. Akcay, H.; Oguz, A.; Karapire, C. Study of heavy metal pollution and speciation in Buyak Menderes and Gediz river sediments. Water Res. 2003, 37, 813–822. [CrossRef] 33. Venugopal, T.; Giridharan, L.; Jayaprakash, M. Characterization and risk assessment studies of bed sediments of River Adyar-An application of speciation study. Int. J. Environ. Res. 2009, 3, 581–598. 34. Khadse, G.; Patni, P.; Kelkar, P.; Devotta, S. Qualitative evaluation of Kanhan river and its tributaries flowing over central Indian plateau. Environ. Monit. Assess. 2008, 147, 83–92. [CrossRef] 35. Mohiuddin, K.; Otomo, K.; Ogawa, Y.; Shikazono, N. Seasonal and spatial distribution of trace elements in the water and sediments of the Tsurumi River in Japan. Environ. Monit. Assess. 2012, 184, 265–279. [CrossRef] 36. Morillo, J.; Usero, J.; Gracia, I. Heavy metal distribution in marine sediments from the southwest coast of Spain. Chemosphere 2004, 55, 431–442. [CrossRef] 37. Soeprobowati, T.R.; Hariyati, R. Phycoremediation of Pb, Cd, Cu, and Cr by Spirulina platensis (Gomont) Geitler. Am. J. Biosci. 2014, 2, 165–170. [CrossRef] 38. Pueyo, M.; Sastre, J.; Hernandez, E.; Vidal, M.; López-Sánchez, J.; Rauret, G. Prediction of trace element mobility in contaminated soils by sequential extraction. J. Environ. Qual. 2003, 32, 2054–2066. [CrossRef] 39. Caeiro, S.; Costa, M.H.; Ramos, T.; Fernandes, F.; Silveira, N.; Coimbra, A.; Medeiros, G.; Painho, M. Assessing heavy metal contamination in Sado Estuary sediment: An index analysis approach. Ecol. Indic. 2005, 5, 151–169. [CrossRef] 40. Rahman, M.; Ziku, A.; Choudhury, T.R.; Ahmad, J.U.; Mottaleb, M.A. Heavy Metal Contaminations in Vegatables, Soils and River Water: A Comprehensive Study of Chilmari, Kurigram, Bangladesh. Int. J. Environ. Ecol. Fam. Urban Stud. 2015, 5, 29–42. 41. Phuong, N.M.; Kang, Y.; Sakurai, K.; Iwasaki, K.; Kien, C.N.; Van Noi, N. Levels and chemical forms of heavy metals in soils from Red River Delta, Vietnam. Water Air Soil Pollut. 2010, 207, 319–332. [CrossRef] 42. Benti, G. Assessment of heavy metals in vegetables irrigated with Awashi River in selected farms around Adama town, Ethiopia. Afr. J. Environ. Sci. Technol. 2014, 8, 428–434. 43. Yadav, A.; Yadav, P.K.; Shukla, D. Investigation of heavy metal status in soil and vegetables grown in urban area of Allahabad, Uttar Pradesh, India. Int. J. Sci. Res. Publ. 2013, 3, 1–7. 44. Prabu, P. Impact of heavy metal contamination of Akaki River of Ethiopia on soil and metal toxicity on cultivated vegetable crops. Electron. J. Environ. Agric. Food Chem. 2009, 8, 818–827. 45. Ammann, A.A. Speciation of heavy metals in environmental water by ion chromatography coupled to ICP–MS. Anal. Bioanal. Chem. 2002, 372, 448–452. [CrossRef] 46. Majumdar, R.C. History of Ancient Bengal; G. Bharadwaj & Co.: Hyderabad, India, 1971. 47. Cenci, R.; Martin, J.-M. Concentration and fate of trace metals in Mekong River Delta. Sci. Total. Environ. 2004, 332, 167–182. [CrossRef] 48. Wade, T.J.; Pai, N.; Eisenberg, J.N.; Colford, J.M., Jr. Do US Environmental Protection Agency water quality guidelines for recreational waters prevent gastrointestinal illness? A systematic review and meta-analysis. Environ. Health Perspect. 2003, 111, 1102–1109. [CrossRef] 49. Nahian, M.; Islam, M.; Kabir, M.; Tusher, T.R.; Sultana, N. Seasonal variation of water quality in Gowain river near Ratargul swamp forest, Sylhet, Bangladesh. Humayun and Tusher, Tanmoy Roy and Sultana, Nargis, Seasonal Variation of Water Quality in Gowain River near Ratargul Swamp Forest, Sylhet, Bangladesh. Grassroots J. Nat. Resour. 2018, 1, 26–36. [CrossRef] 50. Fatema, K.; Begum, M.; Al Zahid, M.; Hossain, M. Water quality assessment of the river Buriganga, Bangladesh. J. Biodivers. Conserv. Bioresour. Manag. 2018, 4, 47–54. [CrossRef] 51. Islam, M.; Rehnuma, M.; Tithi, S.; Kabir, M.; Sarkar, L. Investigation of water quality parameters from Ramna, Crescent and Hatirjheel Lakes in Dhaka City. J. Environ. Sci. Nat. Resour. 2015, 8, 1–5. [CrossRef] 52. Kabir, E.; Kabir, M.; Islam, S.; Mia, C.; Begum, N.; Chowdhury, D.; Sultana, S.; Rahman, S. Assessment of effluent quality of Dhaka export processing zone with special emphasis to the textile and dying industries. Jahangirnagar Univ. J. Sci. 2002, 25, 137–138. 53. Trivedy, R.K. Ecology and Pollution of Indian Rivers; Ashish Pub. House: Delhi, India, 1988. 54. Hakanson, L. An ecological risk index for aquatic pollution control. A sedimentological approach. Water Res. 1980, 14, 975–1001. [CrossRef] Earth 2021, 2 713 55. Arefin, M.T.; Rahman, M.M. Heavy metal contamination in surface water used for irrigation: Functional assessment of the Turag River in Bangladesh. J. Appl. Biol. Chem. 2016, 59, 83–90. [CrossRef] 56. Gan, J.; Jia, X.; Lin, Q.; Li, C.; Wang, Z.; Zhou, G.; Wang, X.; Cai, W.; Lu, X. A primary study on ecological risk caused by the heavy metals in coastal sediments. J. Fish. China/Shuichan Xuebao 2000, 24, 533–538. 57. Srivastava, R.; Sinha, A.; Pande, D.; Singh, K.; Chandra, H. Water quality of the river Ganga at Phaphamau (Allahabad)—Effect of mass bathing during Mahakumbh. Environ. Toxicol. Water Qual. Int. J. 1996, 11, 1–5. [CrossRef] 58. Simpi, B.; Hiremath, S.; Murthy, K.; Chandrashekarappa, K.; Patel, A.N.; Puttiah, E. Analysis of water quality using physico- chemical parameters Hosahalli Tank in Shimoga District, Karnataka, India. Glob. J. Sci. Front. Res. 2011, 11, 31–34. 59. Saravanan, V. Technological transformation and water conflicts in the Bhavani River Basin of Tamil Nadu, 1930–1970. Environ. Hist. 2001, 7, 289–334. [CrossRef] 60. Mohanakavitha, T.; Shankar, K.; Divahar, R.; Meenambal, T.; Saravanan, R. Impact of industrial wastewater disposal on surface water bodies in Kalingarayan canal, Erode district, Tamil Nadu, India. Arch. Agric. Environ. Sci. 2019, 4, 379–387. [CrossRef] 61. Usharani, K.; Umarani, K.; Ayyasamy, P.; Shanthi, K.; Lakshmanaperumalsamy, P. Physico-chemical and bacteriological character- istics of Noyyal River and ground water quality of Perur, India. J. Appl. Sci. Environ. Manag. 2010, 14. [CrossRef] 62. Standard, B. The Environment Conservation Rules 1997; Government of the People’s Republic of Bangladesh: Dhaka, Bangladesh, 63. Agbaire, P.; Obi, C. Seasonal variations of some physico-chemical properties of River Ethiope water in Abraka, Nigeria. J. Appl. Sci. Environ. Manag. 2009, 13. [CrossRef] 64. Premlata, V. Multivariant analysis of drinking water quality parameters of lake Pichhola in Udaipur, India. Biological Forum. 2009, 1, 86–91. 65. Sawyer, C.N.; McCarty, P.L.; Parkin, G.F. Chemistry for Environmental Engineering and Science; McGraw-Hill: New York, NY, USA, 2003; Volume 5. 66. Vishwakarma, C.A.; Sen, R.; Singh, N.; Singh, P.; Rena, V.; Rina, K.; Mukherjee, S. Geochemical characterization and controlling factors of chemical composition of spring water in a part of Eastern Himalaya. J. Geol. Soc. India 2018, 92, 753–763. [CrossRef] 67. Brady, N.C.; Weil, R.R.; Weil, R.R. The Nature and Properties of Soils; Prentice Hall Upper Saddle River: Hoboken, NJ, USA, 2008; Volume 13. 68. National Recommended Water Quality Criteria. United States Environmental Protection Agency, Office of Water, Office of Science and Technology. 2009. Available online: https://www.epa.gov/wqc/national-recommended-water-quality-criteria-tables (accessed on 23 July 2021). 69. Doganlar ˘ , Z.B.; Atmaca, M. Influence of airborne pollution on Cd, Zn, Pb, Cu, and Al accumulation and physiological parameters of plant leaves in Antakya (Turkey). Water Air Soil Pollut. 2011, 214, 509–523. [CrossRef] 70. Sarkar, M.; Rahman, A.L.; Islam, J.; Ahmed, K.; Uddin, M.; Bhoumik, N. Study of hydrochemistry and pollution status of the Buriganga river, Bangladesh. Bangladesh J. Sci. Ind. Res. 2015, 50, 123–134. [CrossRef] 71. Mokaddes, M.; Nahar, B.; Baten, M. Status of heavy metal contaminations of river water of Dhaka Metropolitan City. J. Environ. Sci. Nat. Resour. 2012, 5, 349–353. [CrossRef] 72. Biswas, S.; Rahman, M.; Bahar, A.-U.; Debnath, S. Status of heavy metal in the peripheral rivers around Dhaka city. OIDA Int. J. Sustain. Dev. 2015, 8, 39–44. 73. World Health Organization. Guidelines for Drinking-Water Quality; World Health Organization: Geneva, Switzerland, 1993. 74. Shaw, J. Milk: The Mammary Gland and Its Secretion; Food and Agriculture Organization of The United Nations: Rome, Italy, 2016; p. 89. 75. Ahammed, R.; Harvey, N. Evaluation of environmental impact assessment procedures and practice in Bangladesh. Impact Assess. Proj. Apprais. 2004, 22, 63–78. 76. World Health Organization. Guidelines for Safe Recreational Water Environments: Coastal and Fresh Waters; World Health Organiza- tion: Geneva, Switzerland, 2003; Volume 1. 77. Hamed, M.A. Chemical forms of copper, zinc, lead and cadmium in sediments of the northern part of the Red Sea, Egypt. Pak. J. Mar. Sci. 2007, 16, 69–78. 78. FY 2013 Annual Performance Report FY 2015 Annual Plan Data Quality Records. n.d. Available online: https://nepis.epa.gov/ Exe/ZyNET.exe/P100M5MS.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2011+Thru+2015&Docs=&Query=&Time= &EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay= &IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C11thru15%5CTxt%5C000 00015%5CP100M5MS.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1& FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL& Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL (accessed on 23 July 2021). 79. El-Ebiary, E.; Wahbi, O.; El-Greisy, Z. Influence of dietary cadmium on sexual maturity and reproduction of red tilapia. Egypt J. Aquat. Res. 2013, 39, 313–317. [CrossRef] 80. Fauser, P.; Strand, J.; Vorkamp, K. Risk assessment of added chemicals in plastics in the Danish marine environment. Mar. Pollut. Bull. 2020, 157, 111298. [CrossRef] Earth 2021, 2 714 81. Homady, M.; Hussein, H.; Jiries, A.; Mahasneh, A.; Al-Nasir, F.; Khleifat, K. Survey of some heavy metals in sediments from vehicular service stations in Jordan and their effects on social aggression in prepubertal male mice. Environ. Res. 2002, 89, 43–49. [CrossRef] [PubMed] 82. Ahmad, M.; Islam, S.; Rahman, S.; Haque, M.; Islam, M. Heavy metals in water, sediment and some fishes of Buriganga River, Bangladesh. Int. J. Environ. Res. 2010, 4, 321–332. 83. Mgbenu, C.N.; Egbueri, J.C. The hydrogeochemical signatures, quality indices and health risk assessment of water resources in Umunya district, southeast Nigeria. Appl. Water Sci. 2019, 9, 1–19. [CrossRef] 84. Bhuiyan, M.A.H.; Suruvi, N.I.; Dampare, S.B.; Islam, M.; Quraishi, S.B.; Ganyaglo, S.; Suzuki, S. Investigation of the possible sources of heavy metal contamination in lagoon and canal water in the tannery industrial area in Dhaka, Bangladesh. Environ. Monit. Assess. 2011, 175, 633–649. [CrossRef] [PubMed] 85. ATSDR (Agency for Toxic Substances and Disease Registry). Prepared by Clement International Corp., Under Contract No. 205-88-0608. 2000. Available online: https://www.atsdr.cdc.gov/ (accessed on 23 July 2021). 86. Rahman, M.; Islam, M.; Khan, M. Status of heavy metal pollution of water and fishes in Balu and Brahmaputra rivers. Progress. Agric. 2016, 27, 444–452. [CrossRef] 87. Shama, S.; Moustafa, M.; Gad, M. Removal of heavy metals Fe3+, Cu2+, Zn2+, Pb2+, Cr3+ and Cd2+ from aqueous solutions by using eichhornia crassipes. Port. Electrochim. Acta 2010, 28, 125–133. [CrossRef]

Journal

EarthMultidisciplinary Digital Publishing Institute

Published: Sep 30, 2021

Keywords: river water; pollution; Dhaleshwari; heavy metals; wastewater; ecological risk

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