As a broadly educated microbial ecologist and biogeochemist, I am interested in how microorganisms drive biogeochemical cycles, how their activities are controlled, and how they interact with their biotic and abiotic environment. Current research focuses on the coupling between the biogeochemical cycles of nitrogen, sulfur, and iron in various ecosystems; mostly in sediments and water columns of eutrophic and meromictic lakes, but also including wetlands (fens and bogs), riparian zones, as well as pristine fractured aquifers and polluted porous aquifers. My research is field-oriented with a strong interdisciplinary approach where hydrochemical and quantitative biogeochemical methods are combined with molecular and advanced cultivation techniques of microbial ecology, and where field campaigns are complemented by microcosm experiments and laboratory analyses.