Study of the elemental composition of suspended particles in large northern-Asian lakes （Baikal and Khubsugul）

Lakes Baikal （Russia） and Khubsugul （Mongolia） are rift freshwater water bodies. The maximal depth of Baikal is 1642 m, that of Khubsugul -238 m. One of the important aspects in the study of suspended matter is its geochemical composition which depends on mineralogy and granulometry of the suspended matter. As the concentration of suspended matter in the sites of deep lakes is not high - about 1 mg/L, to determine the elements in the suspended matter the monochromatized synchrotron radiation method （SRXFA, Novosibirsk, Russia） was used. Water sampling was conducted in three basins of Lake Baikal and in Lake Khubsugul on central vertical cross-sections and in near-coastal sites. The water samples were collected with 10-liter batometers. The suspension was extracted from the water by filtration under vacuum through ＂Nuclepore＂ filters of 47 mm in diameter with pore size of 0.4 mkm. The mean weight of dry suspension on the filters was about 1 rag. The results of study of lacustrine suspended matter show that such elements as Fe, Ca, Mn, Ti, V, Cr, Cu, Zn, Pb dominate in lakes Baikal and Khubsugul. The concentration of other elements is low. On the whole, the vertical distribution of total amount of suspended matter in open Baikal decreases from the surface to the bottom. As for Lake Khubsugul, it increases.