Controls of HS, Fe, and Mn on Microbial NO -Reducing Processes in Sediments of an Eutrophic Lake.

Understanding the biogeochemical controls on the partitioning between nitrogen (N) removal through denitrification and anaerobic ammonium oxidation (anammox), and N recycling via dissimilatory nitrate (NO ) reduction to ammonium (DNRA) is crucial for constraining lacustrine N budgets. Besides organic carbon, inorganic compounds may serve as electron donors for NO reduction, yet the significance of lithotrophic NO reduction in the environment is still poorly understood. Conducting incubation experiments with additions of N-labeled compounds and reduced inorganic substrates (HS, Fe, Mn), we assessed the role of alternative electron donors in regulating the partitioning between the different NO -reducing processes in ferruginous surface sediments of Lake Lugano, Switzerland.