Features of Selenium Distribution in Associated Media of Lake Baikal Aquatic Ecosystem

A comparative analysis of distribution of selenium concentrations in the water of the associated media of Lake Baikal ecosystem (surface and deep water of Lake Baikal, well water on Olkhon Island and in the coastal part of the lake, water from numerous tributaries, cold and hot mineral springs, the source of the Angara River and snow water) was performed. The indicator role of Se reflects the deficiency of its concentrations in all aquatic components of the Baikal Region environment. The selenium content in the Baikal water media varies from 0.01 to 3.1 µg/l. The median values are almost similar and lie within one or two orders of magnitude. The increased selenium contents are found in the water of wells and cold springs located in the Jurassic coal-bearing rocks, in the subalkaline granitoids of Olkhon Island. The chemical effect of snow water on the water of the source of the Angara River is possible, that may result in increased concentrations in the source water of Se brought with snow flows from industrial areas of the Baikal Region. We believe that the sharp continental climate, higher seismic activity, and the peculiarities of the water flow in Lake Baikal contribute to the renewal of deep-seated water and to its constant geochemical composition and purity, despite the entry of selenium from man-made sources.