GEOCHEMICAL ASSESSMENT OF MACRO- AND MICROELEMENTS CONTENT IN THE SOIL–PLANT SYSTEM IN THE CONDITIONS OF THE SELENGA AIMAG IN NORTHERN MONGOLIA

The objective of the study is to conduct an ecological and geochemical assessment of the content of macro- and microelements in the soil–plant system in the Selenga aimag of Mongolia. The analysis of the gross content of 14 macro- and microelements in soils and wheat grain using the example of agrocenoses of the Selenga aimag of Mongolia was carried out using the method of mass spectrometry with inductively coupled plasma. During the study, patterns of accumulation of chemical elements in soils and wheat grain of the surveyed territories were established. The gross content of cobalt, copper, chromium, iron and cadmium exceeds the clarke according to K. Videpohl for the corresponding elements, and for arsenic and mercury this excess reaches significant values (for arsenic – up to 6 times, for mercury – up to 600 times depending on the study area). The content of copper, cobalt, nickel, manganese, selenium, lead, chromium and zinc in the soils of all the studied areas does not exceed hygienic standards, and arsenic and mercury are significantly higher than the MAC. A relationship was found between the gross content of chemical elements and agrochemical indicators of soils (humus content, acidity level, salinity). The content of trace elements in the grain of spring soft wheat plants growing in the territories of the Yerey and Tsagaannuur sumons (the Selenga River valley), Baruunburen and Zhavkhlant (the Orkhon River valley) was studied. Only the content of chromium in the wheat grain exceeds the MAC, and the content of arsenic and mercury does not exceed the hygienic standards, despite the high concentration of these elements in the soils of all the surveyed areas. Obviously, this is explained by the protective reaction of plants, preventing the entry of toxic elements into the generative organs. A close relationship was established between the gross content of aluminum, copper, cobalt, manganese, arsenic, selenium, chromium in the soil and their accumulation in plant products. To predict the accumulation of elements in a plant, in addition to the actual content of elements in the soil, it is necessary to take into account a number of factors, for example, the interaction of chemical elements when entering the grain of spring soft wheat, as well as the physiological characteristics of the crop itself.