Complex Assessment of Permissible Pollutant Loads for Freshwater and Terrestrial Ecosystems Using the Selenga River Basin as an Example

An approach to complex assessment of permissible pollutant loads for aquatic and terrestrial ecosystems has been proposed. The approach is based on evaluation of the contaminant removal (assimilation) or inflow rate on the basis of the difference between the mass flow rates at the lower and upper gauging stations of the selected river section. The removal (assimilation) or inflow rate is considered to be the current pollutant load on the river ecosystem (CL R ). The maximum permissible pollutant inflow between the stations calculated on the basis of its maximum permissible concentration (MPC) is the maximum permissible load (MPL R ). The difference between the MPL R and the CL R is considered the remainder of the pollution limit of the river ecosystem or the permissible load. The atmospheric deposition rate of the pollutant is considered its current load on the whole geosystem (CL G ). The sum of the pollutant removal rate due to forest felling and the pollutant assimilation/inflow rate in the river, divided by the area of the drained portion of the water catchment area, is considered the maximum permissible load on the geosystems (MPL G ). The difference between the MPL G and CL G is considered the remainder of the pollution limit of the terrestrial ecosystem or the permissible load.