Formation of the Chemical Composition of Water in Northern Baikal in the Zone of Mixing with the Water of Its Tributaries

The results of studying the chemical composition of water in Northern Baikal and in the rivers flowing into it are analyzed. It is shown that the influence of river water on forming the chemical composition of water in this part of the lake is observed at the distance of 1–3 km from the cofferdam separating the Upper Angara delta from Lake Baikal. In spring and early summer, the expansion of river water in the lake is constrained by a thermal bar. In summer, a biological barrier is formed in the mixing zone, where the minimum biogenic element concentrations of and maximum phytoplankton concentrations are registered. The increased concentrations of phosphorus have been revealed in the shallow area in winter, which points to the contamination of bottom sediments and secondary pollution of water. The increased content of phosphorus in the water may be a sign of the eutrophication of Northern Baikal.