Geoecological characteristics of natural-technogenic complexes of lead-zinc deposits in the Eastern Transbaikal

Abstract

Introduction: Among the natural-technogenic complexes of ore deposits in the Eastern Transbaikal, lead-zinc deposits pose the biggest hazard to the environment. The purpose of the study is to determine the environmental impact of tailings from mining and processing works at lead-zinc deposits in the Eastern Transbaikal. The study provides a comparative assessment of the potential danger of natural-technogenic complexes and identifies the distribution of toxic elements of different hazard classes in ores, technozems, and soils. Methodology: The elemental composition of samples was carried out by X-ray fluorescence in the analytical laboratories at the Geological Institute of the Siberian Branch of the Russian Academy of Sciences (Ulan-Ude). The contents of precious metals were determined by inductively coupled plasma mass spectrometry (ICP-MS) in ZAO SGS Vostok Limited (Chita). The work is based on the factual data collected during the implementation of the basic projects of the Institute of Natural Resources, Ecology, and Cryology of the Siberian Branch of the Russian Academy of Sciences between 2000 and 2020, as well as published data and information provided by the Territorial Geological Fund for the Zabaykalsky Krai (Chita). Results and discussion: It was established that the concentrations of elements in the natural-technogenic complexes of the studied deposits decrease from the first class of toxic hazard to the second class and then to the third class. This can be explained by the ratios of the concentrations of these elements in the ores. It was established that the potential toxicity of lead-zinc deposits in the Eastern Transbaikal corresponds to the toxicity indicators of lead-zinc deposits. The content of precious metals in heavy concentrates of technozems in the Akatuevsky deposit is: up to 3.0 g/t of Au and up to 20.9 g/t of Ag; in Blagodatsky deposit it is up to 1.8 g/t of Au and up to 22.0 g/t of Ag. Conclusion: It was revealed that among the natural-technogenic complexes of lead-zinc deposits in the Eastern Transbaikal, the biggest environmental hazard is posed by the soils in the area of Savinsky deposit No. 5. The total soil pollution is Z c =126.3, which corresponds to a danger level. The minimum indicators of soil pollution among the studied deposits were established for the Novo-Shirokinsky deposit Zc =41.9, which also corresponds to the danger level for soil pollution (Zc = 32–128).