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SUMMARY:Biogeochemical processes controlling the speciation and mobility o
 f trace metals in contaminated floodplain soils
DTSTART:20101129T161500
DTSTAMP:20260407T210759Z
UID:2749f9bef3d68557a6faf97b5aa36317d6142c5e5a6e4bf89822194f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Kretzschmar\, Ruben\nDuring the past decades to centuries\, ma
 ny river floodplains in Europe and other industrialized regions of the wor
 ld have served as sinks for inorganic and organic contaminants released in
 to rivers with urban wastewater and runoff\, industry\, mining\, and other
  human activities. Such historically contaminated floodplain soils may rel
 ease contaminants into rivers and groundwater even long after the original
  contamination sources have been remediated. They therefore can pose a con
 tinued threat to water quality and ecosystem health. Biogeochemical proces
 ses in floodplain soils are highly dynamic\, e.g.\, periodic flooding and 
 drainage induce pronounced soil reduction and oxidation cycles. Our curren
 t research aims at a better understanding of the speciation changes and mo
 bility of trace metals and metalloids during redox fluctuations in contami
 nated floodplain soils\, in order to improve predictions of contaminant mo
 bility and toxicity.\n\nDifferent biogeochemical processes can lead to inc
 reasing or decreasing trace metal mobility during prolonged soil flooding.
  Reductive dissolution of iron and manganese oxyhydroxides results in a lo
 ss of sorbent surfaces and increased concentrations of dissolved Fe2+ and 
 Mn2+ in solution\, which promotes the release of adsorbed trace metals. Ad
 ditionally\, increasing concentrations of dissolved organic carbon in pore
  water can contribute to trace metal mobilization. On the other hand\, tra
 ce metals can be immobilized as a result of rising pH and by formation of 
 poorly-soluble sulfide minerals during sulfate reduction. The potential fo
 r trace metal immobilization by sulfate reduction\, however\, depends on t
 he concentrations of sulfide-forming trace metals and of available sulfate
  present in the soil. The amount of sulfate in river floodplain soils can 
 become the limiting factor\, in which case formation of the most insoluble
  metal sulfides (e.g.\, CuS) consume most available sulfide\, leaving othe
 r chalcophile metals in more mobile forms. However\, chalcophile metals ca
 n also bind to reduced sulfur groups of soil organic matter. Recent result
 s suggest that prolonged soil flooding can also lead to the formation of m
 etallic Cu(0) and sulfide colloids in the pore water\, which may be mobile
  and thereby increase trace metal mobility. In this presentation\, our rec
 ent research on trace metal speciation and mobility in river floodplain so
 ils will be presented and discussed.
LOCATION:GR A3 31
STATUS:CONFIRMED
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