Assessing the Geoecological Status of the Floodplain-Terrace Complex of the Tuul River Within Ulaanbaatar (Mongolia)

摘要

The paper gives characteristics of natural and anthropogenic factors responsible for the geoecological situation inside the boundaries of the floodplain-terrace complex of the Tuul river within Ulaanbaatar. Among them, the geological structure and orography (occurrence in the intermontane depression), the specific character of climate-forming (frequent temperature inversions) and hydrological (mainly summer feed by rain water) characteristics, the degree of economic development (high pressure on the central city zone) and population density in administrative districts, etc. have been distinguished. Results obtained from hydro- and geochemical analyses of the territory and published previously (during 2009-2013) were used in the typification of the areas of the floodplain-terrace complex of the Tuul river according to the intensity of anthropogenic impact. An analysis was made of the sources of pollution, primarily of large industrial enterprises and facilities of housing and communal services: combined heat and power plants, industrial, meat-packing and biological plants, the poultry farm, sewage treatment plants, etc. Based on a comparative analysis of average concentrations of the component composition of the river waters and floodplain soils, maximum exceedances of maximum and approximate permissible concentrations of pollutants were determined. Categories of the intensity of anthropogenic impact were identified to vary from decreased to very high. It is shown that, in spite of a high degree of geochemical understanding of the urban territory of Ulaanbaatar, no detailed investigations have been made within the floodplain-terrace complex of the Tuul river. The first-time assessment of the geoecological status of the sites across the study territory determined the migration routes of chemical substances and correlated their occurrence in natural environment with the sources of pollution. According to the intensity of anthropogenic impact, for each site of the flood