ECOGEOCHEMICAL CHARACTERISTICS OF THE YARLY-AMRY AND THE CHIBITKA RIVERS, LOCATED IN THE DISPERSION TRAIN OF AKTASH MERCURY DEPOSIT AND ITS WASTES (GORNY ALTAI)

The relevance of the study is caused by the need to develop Russian guidelines for assessing the environmental state of bottom sediments and their impact on living organisms, as well as water bodies in general. The pollution of natural waters by potentially toxic elements is currently important. There are no federal standards regulating the quality of bottom sediments in Russia. Additionally, the study area is located in a popular tourist region of Gorny Altai. The knowledge about environmental state of the aquatic ecosystem in this region is of great importance. The main aim is to study the potentially toxic elements (Hg, As, Cu, Zn, Ni, Pb, Cd, Sb, Se) distribution in the waters and bottom sediments of the Yarly-Amry and the Chibitka Rivers and assess the environmental state of bottom sediments based on Russian and International guidelines as well as identify their toxicity to living organisms. Study area. The Chibitka River and its tributary, the Yarly-Amry River (Ulagan District, Aktash village) are located within the Kurai mercury zone and are additionally influenced by the Aktash Mining and Metallurgical Enterprise wastes stored on the Yarly-Amry River bank. Methods. pH and Eh were measured in waters by potentiometry. The dissolved Corg was determined by IR spectroscopy. The anions were studied by capillary electrophoresis. The potentially toxic elements contents in river waters were determined by flame and electrothermal atomic absorption spectrometry, as well as by mass spectrometry with inductively coupled plasma; Hg was determined by «cold vapor» atomic absorption spectrometry. The PTE contents in bottom sediments were determined by SR-XRF, flame and electrothermal atomic absorption spectrometry and «cold vapor» atomic absorption spectrometry. The geochemical features of bottom sediments were identified calculating their enrichment degree relative to the upper continental crust. The pollution degree of bottom sediments and the toxic impact probability on living organisms were estimated based on a comparison of potentially toxic elements content with Russian and International guidelines. Results. The increase of Cu, Cd, Hg and Se total contents in river water takes place due to the effect of Aktash Mining and Metallurgical Enterprise wastes on the Yarly-Amry River. The contents of Ni, Zn, As, Pb, Sb are higher in the source of Yarly-Amry River than in the part of the river affected by Aktash Mining and Metallurgical Enterprise wastes. The Chibitka