The estimation of chemical content of surface waters in Neryungri coal-mining region of Southern Yakutia

Abstract

The content of main iones, biogenic elements and microelements – heavy metals (HM) in surface waters of Neryungri coal-mining region of Southern Yakutia have been studied. The complex of analytical and instrumental chemical methods of analysis has been applied. It was found that coal of Neryungi coal mine is characterized by average ash content of 12-20 %. The ash consisted predominantly of silicon (40-60 %) and aluminum oxides (16-22 %), and also contained Fe, Ca and Mg oxides of 8-14, 4-10, 2-4 % respectively. The aqueous suspension of oxidized coals had pH value of 7,1-7,2, they contained approximately 1 % of сommon N and about 0,01% of both total K and P, and 0,15-0,45 % of S, thus these coals were classified as low-phosphorus and low-sulfur. Also, these coals did not contain considerable amount of heavy metals such as As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb and Zn. It is evident that during the past 40-years period of coal mine operation the chemical composition of the Chulman River and its tributaries within the mining area has changed significantly.

Thus pH value has increased by 0,5, the total mineralization and hardness of water increased more than 3 fold, while the water type has not changed and remains of hydrocarbonate-calcium type. The content of nitrates and total P increased 5 and 3 times respectively. The content of Cr has changed from 1,0 to 1,7 mg/L, Cu – from 0,7 to 4,0 mg/L, Mnfrom 10,0 to 50,0 mg/L, Mo – from 0,5 to 0,8 mg/L and Zn – from 5,0 to 18,0 mg/L. The content of other heavy metals estimated by the atomic emission spectrometry method was below the detection limit. It should be also noted that the content of all studied heavy metals did not exceed the maximum permissible concentration determined by State Standard Specifications and Sanitary and epidemiological regulations and guidelines. Therefore, at present as well as before, the water of the Chulman River satisfies the sanitary requirements and regulations for water quality, and may be used for drinking water supply.