Many riparian wetlands throughout Europe have been contaminated with heavy metals due to upstream emissions from mining and smelting, industrial production, and waste water discharge . During temporary flooding of riparian wetlands, soil respiration may cause rapid depletion of oxygen followed by microbial reduction of alternative electron acceptors such as Fe(III)-(hydr)oxides and sulfate. Mechanisms possibly affecting the fate of heavy metals under reducing conditions include the reductive dissolution of sorbent phases (Fe(III)-(hydr)oxides, Mn(III,IV)-oxides), competitive cation adsorption (e.g., heavy metal displacement by Fe2+), and the formation of heavy metal bearing precipitates . Based on preliminary work, we hypothesize that sulfide generated by microbial sulfate reduction leads to the formation of sparingly soluble Cu-, Pb-, and Cd-sulfides. While the precipitation of sulfide minerals in the immobile soil matrix likely retards contaminant mobility , formation of sulfide colloids in the pore water might strongly enhance the mobility of Cu, Pb, and Cd by colloid-facilitated transport . In order to determine the effect of sulfide generation on the speciation and mobility of heavy metals in a contaminated wetland soil, we performed laboratory incubation experiments and used X-ray absorption near edge structure (XANES) spectroscopy to analyze the speciation of Cu Show more
Book titleANKA Annual Report 2007
PublisherISS Institute for Synchrotron Radiation
Organisational unit03621 - Peter, Markus
03541 - Kretzschmar, Ruben
NotesPublication date 30. September 2007.
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