Artifacts in the Determination of Trace Metal Binding Forms in Anoxic Sediments by Sequential Extraction |
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| Authors: | K Wallmann M Kersten J Gruber U Förstner |
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| Institution: | 1. University of Bremen, Fachbereich Geowissenschaften , P. O. Box 330440, D-2800, Bremen 33, F. R. G.;2. University of Technology Hamburg-Harburg, Dept. of Environmental Science and Engineering , P. O. Box 901052, D-2100, Hamburg 90, F. R. G. |
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| Abstract: | Abstract The binding forms of Co, Cd, Cu, Pb, and Zn in an anoxic, sulfide-bearing sediment were investigated by performing both thermodynamic equilibrium calculations and sequential extractions. Care was taken to maintain oxygen-free conditions during the whole experiment. The calculations suggested that trace metals were bound to sulfidic minerals. Sequential extraction results, however, showed increased importance of exchangeable and reducible fractions in the order Cu < Cd < Pb < Zn < Co. Thermodynamic equilibrium calculations of the chemical reactions during extraction showed that Cd, Co, Pb, and Zn sulfides are to a significant extent soluble in the acetate-exchangeable (step 1 + 2) and oxalate-reducible (step 3) fractions. Neglecting the dissolution of sulfide minerals would lead to a misinterpretation of the experimental results. |
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| Keywords: | Sequential extraction speciation anoxic sediments cadmium cobalt copper lead zinc |
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