New publication in Frontiers in Environmental Chemistry: "Large extent of mercury stable isotope fractionation in contaminated stream sediments induced by changes of mercury binding forms"


Mercury (Hg) release from contaminated legacy sites is a large contributor to riverine ecosystems and can represent a significant local and regional environmental issue even long after the initial site contamination. Understanding processes of in-stream species transformation is therefore important to assess the fate and bioavailability of the released Hg.

In this study, Prof. Stephan Krämer together with PhD student Lorenz Schwab, former University assistant Dr. Jan Wiederhold and MSc student Florian Rothe collected stream sediments downstream of a former kyanization facility in the Black Forest, SW Germany, where highly soluble Hg(II)-chloride (HgCl2) was used as an anti-fouling agent to treat timber. We investigated in-stream Hg transformation processes with analyses of Hg binding forms and Hg stable isotopes.

The large extent of Hg isotope fractionation observed in stream sediments resulted from a combination of kinetic isotope effects during sorption, redistribution of Hg within the sediment and the preferential transport of Hg associated with the sediment fine fraction.