Iron from Lignite Mining Increases Phosphorus Fixation in Sediments, but Does Not Affect Trophic States of Lakes Along River Spree (Germany)

Abstract To mitigate lake eutrophication, phosphorus (P) availability can be managed by iron (Fe) amendments, which bind P in the water column and settle as Fe oxy-hydroxides. In fluvial-lacustrine system Spree, oxy-hydroxides enter lakes due to lignite mining Lusatian Area (NE Germany). We hypothesized that amount of retained from sediments is positively correlated with their content. Column experiments were used investigate uptake release under oxic anoxic conditions three downstream (Lake Neuendorfer See, Lake Glower Müggelsee) decreasing influence thus loads, one nearby non-mining-affected Schwielochsee). interconnected River cumulative increased significantly increasing sedimentary concentrations both conditions. Only See had higher than conditions, most likely vivianite formation. The net sedimentation was concentration However, are classified eutrophic because although Spree store further P, this additional little relevance for budget highly P-loaded short residence times (10–100 d), typical systems.