Metals in the Waters of the Southern Tributaries of Lake Baikal

We examine the composition of metals in the waters of the southern tributaries of Lake Baikal as well as comparing it with the composition of metals in bottom sediments and calculating the water migration coefficients of metals. The territory of the southern part of the lake drainage basin was regionalized according to the ability to ensure a particular water composition. The contribution from the southern tributaries to the chemical composition of Lake Baikal water was evaluated. It was found that the composition of macroelements and trace elements in the waters varies over a broad range. There occur waters with salt contents far exceeding those in Baikal water and its main tributaries as well as with considerably lower salt contents. Macroelements in the waters of all the streams studied are absolutely dominated by calcium, whereas the waters differ greatly in magnesium and sodium contents. Trace elements in the waters of the rivers on the southwestern coast are dominated by strontium, vanadium and molybdenum, which significantly differs them from the waters of the rivers of the southeastern coast, Lake Baikal and its main tributaries. The values of the water migration coefficients as calculated for the macroelements in the waters of the southern and main tributaries of Baikal are similar. The water migration coefficient of trace elements for the river waters in the study area differ greatly from the coefficients for the waters of the main tributaries of Baikal. The reason behind this is the existence of sources of dissolved matter, such as rocks and deep underground water, with their composition not characteristic for corresponding landscapes. The contribution from the southern tributaries to the macroelement composition of Lake Baikal waters can be estimated at the range of 5 to 30% depending on the selected tracer metals. The contribution from the southern tributaries to the trace element composition of the Baikal waters defies estimation because of their much higher concentrations in the rivers when compared with Baikal water. The differences in the trace element concentrations in the water of Baikal water and of its tributaries are caused by their migration in the composition of organic matter. In consequence of a long period of water exchange in Baikal, this matter is deposited or decays thus promoting the removal of trace elements from solution.