Evaluation of the content and migration of heavy metals in components of river ecosystems’ of mining territories of the Republic of Bashkortostan

Abstract

Exploration and development of mineral deposits in the Transurals of the Republic of Bashkortostan are accompanied by a comprehensive environmental impact. Ones of the most vulnerable elements of the landscape are the surface water bodies used for fishery purposes, recreation and household needs of the population. Extraction and processing of ores lead to the contamination of aquatic ecosystems by heavy metals (HM), which by passing into a pond, can actively be involved in the cycling of matter and migrate via food chains to the human under the consumption of fish products. Possessing by cumulative properties, HM can express mutagenic, teratogenic and carcinogenic properties. The aim of research was the study of the impact of mining facilities on the content of the priority HM in the components of river ecosystems in the Transurals of the Republic of Bashkortostan and the development of a complex of preventive measures on the improvement of the human environment. There was studied the content of Zn, Cu and Cd in the water, bottom sediments and phytomass of Elodea canadensis Michx. The measurements of mass concentrations of metals were performed by stripping voltammetry with the use of the STA device. The results showed that for the cross-sections there is typical the following descending series of elements in the river components: Zn > Cu > Cd. In water samples there is observed the exceedance of standards for water bodies of potable, cultural and community water use and fishery basins. The concentration of zinc varies in the range of 0.016-5.24 mg/dm; copper - 0.0024-0.095 mg/dm; cadmium - 0.0001-0.019 mg/dm. In bottom sediments, in general, the content of metals in comparison with control plots is increased to the tenfold value. The meaning of mobile forms of zinc in the ground varies in the range of 0.81-9.62 mg/kg; copper - 0.12-18.69 mg/kg; cadmium - 0.00013-0.092 mg/kg. The zinc concentration in above-ground phytomass of Elodea canadensis compared to control increases by 2-3.5 times, copper - 4-8 times, cadmium - 2-7 times. Univariate analysis of variance confirmed the accuracy of the impact of the degree of contamination on the accumulation of metals by Elodea canadensis. The results testify to the potential danger to health of water bodies of the region’s population.