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Metal complexation by organic ligands (L) in near-pristine estuarine waters: evidence for the identity of L

Metal complexation by organic ligands (L) in near-pristine estuarine waters: evidence for the... Environmental contextMetal toxicity to marirne organisms is largely controlled by organic ligands (L) although the source, structure and stimuli of most ligands remain unknown. We studied trends in Cd and Zn complexing ligands in a near-pristine Irish estuary to gain clues on the identity of L in natural waters. The evidence suggests the naturally occurring Cd ligands include fulvic acids whereas the Zn ligands are likely to be exuded from seaweeds. Further research is required to determine their exact identity.AbstractTrace metal interactions with organic ligands largely control metal bioavailability in marine systems, although little is known about the identity of the ligands. To gain insight into the identity of metal complexing ligands (L), surface water and four species of brown seaweed were sampled from four sites in a region of the Lough Furnace Estuary, Ireland with varying salinity. We measured metal (Cd, Cu, Pb, Zn) speciation, complexing ligands, stability constants (log K), glutathione (GSH), cysteine (Cys) and seaweed metal contents. Although prevalent in seaweed tissue, dissolved Cu and Pb concentrations in water were below the detection limits. Both Cd and Zn occurred in seaweed tissue. In water, both Cd and Zn occurred predominantly complexed to ligands. Levels of complexed Zn increased with decreasing salinity, increasing from 77 at high salinity to 100 at low salinity. Total dissolved Cd showed a mid-salinity decrease in complexation. The concentration of zinc ligands (LZn) ranged from 27.41nM at high salinity to 95.81nM at mid-salinity. Cd ligands (LCd) occurred in the highest concentration, 8.72nM, at mid-salinity. Comparison of the log K values with known ligands provided evidence of their identity: similarities were identified for LCd and fulvic acid, and LZn and macroalgal exudates. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Environmental Chemistry CSIRO Publishing

Metal complexation by organic ligands (L) in near-pristine estuarine waters: evidence for the identity of L

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References (92)

Publisher
CSIRO Publishing
Copyright
Copyright © The Author(s). Published by CSIRO Publishing
ISSN
1448-2517
eISSN
1449-8979
DOI
10.1071/EN13084
Publisher site
See Article on Publisher Site

Abstract

Environmental contextMetal toxicity to marirne organisms is largely controlled by organic ligands (L) although the source, structure and stimuli of most ligands remain unknown. We studied trends in Cd and Zn complexing ligands in a near-pristine Irish estuary to gain clues on the identity of L in natural waters. The evidence suggests the naturally occurring Cd ligands include fulvic acids whereas the Zn ligands are likely to be exuded from seaweeds. Further research is required to determine their exact identity.AbstractTrace metal interactions with organic ligands largely control metal bioavailability in marine systems, although little is known about the identity of the ligands. To gain insight into the identity of metal complexing ligands (L), surface water and four species of brown seaweed were sampled from four sites in a region of the Lough Furnace Estuary, Ireland with varying salinity. We measured metal (Cd, Cu, Pb, Zn) speciation, complexing ligands, stability constants (log K), glutathione (GSH), cysteine (Cys) and seaweed metal contents. Although prevalent in seaweed tissue, dissolved Cu and Pb concentrations in water were below the detection limits. Both Cd and Zn occurred in seaweed tissue. In water, both Cd and Zn occurred predominantly complexed to ligands. Levels of complexed Zn increased with decreasing salinity, increasing from 77 at high salinity to 100 at low salinity. Total dissolved Cd showed a mid-salinity decrease in complexation. The concentration of zinc ligands (LZn) ranged from 27.41nM at high salinity to 95.81nM at mid-salinity. Cd ligands (LCd) occurred in the highest concentration, 8.72nM, at mid-salinity. Comparison of the log K values with known ligands provided evidence of their identity: similarities were identified for LCd and fulvic acid, and LZn and macroalgal exudates.

Journal

Environmental ChemistryCSIRO Publishing

Published: Apr 3, 2014

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