Formation of waters of tungsten-ore areas under the influence of natural and anthropogenic factors (Eastern Transbaikalia, Russia)

Abstract

The industrial development of tungsten deposits in Eastern Transbaikalia contributed to a significant deterioration of the environmental situation in the adjacent territories. Heavy-metal water contamination has become a serious problem in the mining areas. The most dangerous are wastes of sulphide ores, the oxidation of which leads to the formation of acidic drains with abnormally high concentrations of heavy metals. The features of the composition of the waters formed in and around the five tungsten deposits were studied and significant differences in their physical and chemical characteristics were shown. The most saline acidic, sulphate waters with the maximum content of heavy metals are recorded in the drainages of the tailings of beneficiation plants and rock dumps and in the ponds of sludge depositories and deposits with an increased ore sulphide content. The groups of elements posing the greatest danger to aquatic ecosystems were identified as Cd, Cu, Zn, Be, Al, Co, Th, Mn in acidic and slightly acidic waters and W, Mo, U, As, Mn in slightly alkaline and alkaline waters. Based on the Eh-pH water parameter ratio, three types of hydrogeochemical environments formed in the mining areas of tungsten deposits were identified. Metal migration in the waters occurs mainly in the form of simple cations, sulphate, fluoride, hydrocarbonate, carbonate and hydroxyl complexes. Geochemical barriers of oxygen, sorption, acidic and alkaline types were studied in the areas around the deposits. The main factors determining the physical and chemical parameters of the waters are shown, including the regional factor, specifically, the ore and host rock composition, the water exchange intensity, and the technogenic factor, which causes a high level of water pollution.