My group´s research aims at identifying and quantifying chemical and (micro)biological processes that govern fate and transport of essential and potentially toxic trace elements in the geosphere, pedosphere, and hydrosphere. Our major focus is to go beyond total element quantification, instead identify individual species both in the aqueous and associated to the solid phase (minerals, organic matter).
Many of the elements we are interested in are redox-sensitive, i.e. they change in composition under oxic and anoxic conditions. A major challenge is preservation and determination of so-called intermediate species which are transient in nature but highly reactive and therefore often drive and interlink biogeochemical cycles. Their occurrence at trace concentrations requires dedicated analytical techniques. We have specialized in our laboratory on quantification of aqueous species by coupling of ion chromatography to inductively coupled plasma mass spectrometry (IC-ICP-MS) and regularily use X-Ray Absorption Spectroscopy at international synchrotron facilities for structural characterization of aqueous and solid phase species. For species-selective isotope fractionation investigations we have established collaboration for determination by chromatography coupled to multicollector ICP-MS.
We study ancient systems (palaeo Ocean analogues) and modern systems, which are often geogenically impacted (geothermal sites, paddy soils and rice plants, peatlands, groundwater) or anthropogenically contaminated (mine sites, treatment peatlands). Over the past years, a special focus has been on interlinkages of the sulfur cycle with other trace elements (As, Sb, Fe, Mo, W, Cu, Ni, Cd) including discovery and full characterization of novel species, so called thiolated metal(loid)s, with regard to formation, transformation, mobility, availability and toxicity to microorganisms and plants.