Hydrogeochemische Speziierung von Arsen, Gold und Kupfer in Eisen-Sulfid-Systemen unter Berücksichtigung abiotischer und mikrobiell katalysierter Wechselwirkungen

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Complexation of arsenic and sulfur has a significant - and so far seldom considered - impact on inorganic arsenic chemistry in suboxic aquatic environments, such as precipitation of amorphous arsenic-sulfur phases during acidic sample preservation, erroneous species identification during hydride generation, and changes in mobility, redox behavior, and toxicity. The proposed project will start by improving preservation and analytical techniques (IC-ICPMS) for (thio)arsenic species in ferrous-sulfidic systems which have a worldwide importance since they host various economically interesting ore bodies and drinking water aquifers. Laboratory batch and column experiments will show the effect of thioarsenate solution and surface complexation on arsenic sorption to and remobilisation from iron(hydr)oxides and iron-sulfides in the absence and presence of gold and copper. Field studies will include ore formation processes within active geothermal systems, natural weathering processes at mine sites, and redox processes within reactive iron barriers. A special focus of the project is the determination of importance and rate of microbially catalyzed versus abiotic species transformations of thioarsenates in laboratory growth experiments and under natural conditions including characterization of the respective microbial communities.