The biogeochemical fate and toxicity of mercury in Controlled Experimental Ecosystems |
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| Authors: | Gordon T Wallace Don L Seibert Susan M Holzknecht WH Thomas |
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| Institution: | 1. Skidaway Institute of Oceanography, Post Office Box 13687, Savannah, Georgia 31406, U.S.A.;2. Institute of Marine Resources, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, U.S.A.;3. National Oceanic and Atmospheric Administration, Atlantic Oceanographic Marine Laboratory, 15 Rickenbacker Causeway, Miami, Florida 33149, U.S.A. |
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| Abstract: | The affinity of mercury for organic matter was the most important parameter governing its chemical speciation, transport and toxicity in Controlled Experimental Ecosystems (CEEs) of the Controlled Ecosystem Pollution Experiment (CEPEX) deployed in Saanich Inlet, B.C., Canada, Particulate, colloidal and high molecular weight dissolved forms of mercury accounted for about 90% of the total mercury present in the water column. Bioassays indicated that organic matter in the above size classes had an important influence on the toxicity of mercury to phytoplankton.Sorption of mercury to particulate organic matter in the CEEs could be described by either Freundlich or linear adsorption isotherms. An observed depth-dependent increase in mercury content of particulate matter was attributed to selective biological degradation of non-mercury-binding organic components of the particles during settling.The high affinity of mercury for settling particulate organic matter led to rapid removal of mercury from CEEs. Removal rates could be described as first order and were a function of primary production rates. Deviations of measured half-removal times from those predicted by an empirically formulated relationship between primary production and mercury half-removal times could be related successfully to the influence of other occasionally significant biological parameters such as zooplankton grazing activity. |
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| Keywords: | mercury biogeochemistry transport toxicity speciation British Columbia |
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