Eco-Geo-Chemistry of Mercury in Soils and Coals of the South of Kuzbass

Abstract

Assessment for content of mercury as a toxic component of coal combustion by-product in rocks and deposit environments is aimed at identification of risks caused by impact of hazardous activities on the environment in full concordance with green chemistry concept. In this paper have been presented results of mercury content determination for the South Kuzbass coals and soils of the coal-mining area. The mercury contents in soils (30 samples) and coals (30 samples) were determined by atomic absorption method on the RA‑915+ mercury analyzer with pyrolytic attachment. The mercury content in Mezhdurechensk strip mines’ coals varies from 0.13 to 2.46 mg/kg with the average concentration of 0.57±0.10 mg/kg. The determined content exceeds the Clarke of mercury in coals by factor of 1.3 to 24.6. The mercury content in soil samples varies from 0.012 to 0.173 mg/kg with the average value of 0.057±0.007 mg/kg, which is by 1.7 times more than the average mercury content in the Earth crust. There are five locations within Mezhdurechensk city area where the mercury content in the soil exceeds 3.1–5.3 times the Clark value. During past 25 years the average mercury content in the soil has been decreased by 2.8 times. The solubility of mercury from technogenic landscapes’ soils has been studied by methods of successive acetate-ammonium and hydrochloric acid extracts. The solubility of mercury in aqueous extracts from Mezhdurechensk soils is by 2.2–2.9 times higher than the ones taken from undisturbed landscapes, in acetate-hydrochloric acid and alkaline extracts it is within the limits of content in natural soils; in strongly acidic extracts has been found the maximum solubility of mercury (30.6–84.8% from the total amount). Based on the major contribution of coal dust in the gross input of mercury into the environment of Mezhdurechensk, it is possible to expect the increasing of mercury background in and around the city caused by the growth of coal mining in the area without implementation of modern and effective methods for dust suppression.