The State of the Lake-river System Affected By Mineral Production

Abstract

The current state of four water bodies in the upper and middle reaches of the River Kenti system, Western Karelia, affected by long-term industrial potassium-sulphate pollution, is assessed. The upper water body of the system, Lake Kostomukshskoye, is supplied by waste water from an iron mining concentration plant. Lakes Okunevoye, Poppalijärvi and Koivas are located downstream. Analysis of some hydrochemical indices and phyto- and zooplankton communities has shown that as the distance from the pollution source increases, the hydrological regime is stabilized, species diversity increases and the quantitative indices of the biotic constituent of the lake-river system grow. For example, the total mineralization value decreases from 632 дo 45 mg/l, the concentrations of major polluting agents, such as K+ and Na+ ions, decline by an average of two orders of magnitude and the medium reaction passes from alkaline (pН 7.7) to neutral (pН 6.8). The species composition of the phytoplankton varies from 18 to 23 species of six 6 divisions. The number of zooplankton taxa increases from 15 to 24 and average quantitative indices grow from 0.048 g/m3 (1.1 thousand individuals/m3) to 0.368 g/m3 (10.3 thousand individuals/m3), respectively. The data obtained were compared with earlier results.