Assessment of the Load of Nutrients and Pollutants on the Russian Part of the Irtysh River

Abstract

The ILLM model was used to solve the problem of assessing the external load on the Russian part of the Irtysh River from the catchment. It takes into account the contribution of point and diffuse sources to the formation of the load and makes it possible to calculate the removal of impurities from the catchment. The model takes into consideration the influence of hydrological factors and chemical retention by the catchment and its hydrographic network. In order to provide the model with the necessary input information, the underlying surface types have been classified using PROBA-V and Sentinel-2 satellite images. Data on the content of nutrients (N and P) and trace elements (Cu and Zn) in soil and river waters of the studied territory have been collected and analyzed. Based on the processing of materials on the activities of more than 800 agricultural enterprises, the number of livestock and organic and mineral fertilizer inputs are estimated and the total nitrogen and total phosphorus inputs to the hydrographic network are calculated. The external load (including the diffusive component) of nutrients (nitrogen and phosphorus) and metals (copper and zinc) is assessed for both the entire Russian part of the Irtysh basin and for seven of its subbasins, including the Tobol, Ishim, Om, and Konda rivers. According to the results, the contribution of the transboundary load to the outflow of the considered chemicals in the outlet sections of the transboundary rivers is evaluated. It is shown that the ratio of the contribution of different components of the external load to the outflow varies depending on the water content of a year.