Phosphate Minerals in the Bottom Sediments of Lake Onega from the Upper Neopleistocene to the Holocene

This study investigates phosphorus-bearing minerals in the bottom sediments of Lake Onego and its proglacial precursor. The composition of phosphorus mineral phases differs in the Late Neopleistocene glaciolacustrine and Holocene lacustrine deposits. The former are dominated by fluorapatite, monazite, and xenotime, whereas the Holocene sediments,represented by fine-grained lacustrine muds,contain significant amounts of vivianite and Fe–Mn hydroxides. These differences revealed changes in phosphorus sources and conditions of its accumulation, which is important for assessing the trophic state of Lake Onega at all stages of its development under climatic and anthropogenic changes.