Geochemistry of Phosphorus in the Freshwater Lake Sediments of Northeastern Russia

Phosphorus distribution in lacustrine sediments, deluvial sediments, and bedrock was investigated. In the deluvium formed after felsic and basic rocks, phosphorus, like iron and manganese, is concentrated in fine grain-size fractions. The main supply of phosphorus to lake basins is associated with discharge of detrital material from the catchment area. In bottom samples from the surface layer of the lakes, as well as in the deluvial sediments, phosphorus enriches fine clay sediments in the deep parts of basins. Zones with high concentrations of P2O5, Fe2O3, MnO, and sometimes CaO have been identified in lacustrine sections. They are characterized by an accumulation of vivianite. It is assumed that phosphorus was also adsorbed by iron hydroxides, ferromanganese aggregates, and clay minerals. Peaks in phosphorus concentrations are observed in sediments of both cold and warm climatic stages.