Ecological and geochemical assessment of the distribution of toxic elements in the soil cover in the impact zone of a mining and processing plant (using the example of the Khapcheranginsky mining and processing plant (Transbaikal Territory))

The paper presents data on the level of contamination of soil cover and technozems approximately the Khapcheranginsky mining and processing plant with 53 chemical elements. For more than 40 years, the enterprise has not been functioning, and processed rocks are stored on the surface, causing powerful technogenic pollution of the area. Reclamation measures have not been carried out, and tailings are not being properly operated. When analyzing the level of pollution in the settlement, it was found that in the technogenic zone the arsenic content exceeded the Threshold Limit Value (TLV) by 130 times (26 times the excess of the Approximate allowable concentrations (AAC), cadmium - 5,7 AAC, copper - 42 TLV, lead - 26,6 TLV (6,6 AAC), antimony - 1,7 TLV, zinc - 81,5 TLV (8,5 AAC). For the residential zone, excess of standard values was noted for the following elements: arsenic - 20-fold excess of TLV (4 AAC), copper - 17 TLV, lead - 3 TLV, antimony - 1.8 TLV, zinc - 14,5 TLV (1,5 AAC) ) For the background territory, an excess of Threshold Limit Value (TLV) for arsenic (13-fold) and zinc (4 TLV) was noted, but this is probably due to the natural geochemical features of this region of southern Transbaikalia. The total pollution by the value of the Saeta index (Zc) in the tailings area was 269,6 units, which characterizes the technogenic zone as extremely polluted, the residential zone had a coefficient value of 75,6, and the background zone -27,7, which indicates a high level of soil contamination chemical elements, some of which are highly toxic. The main contribution to the total pollution index, according to the pollution index, belonged to the elements: As, Bi, Cd, Cu, In, Li, Pb, Sb, Sn, W, Zn, the contents of which in the conditions of the technogenic zone of the village of Khapcheranga are many times higher than the standard values. In terms of the geoaccumulation index (Igeo), the most significant toxic elements in the composition of technozems were arsenic and lead. The same elements together with tin had critical values in terms of the soil enrichment factor (EF (Pb) = 68,3, EF (As) = 61,6, EF (Sn) = 32,4), especially in the conditions of the technogenic zone. Thus, in the territory of the village of Khapcheranga and its environs, geo-chemical anomalies of natural and technogenic origin with an increased content of heavy metals (zinc, antimony, lead, cadmium) and arsenic, which have high carcinogenic activity, leading to teratogenic effects with immunosuppressive properties, were formed with complex exposure

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