Geochemical study of Lake Imandra, Russia : evaluation of effect of mining industries on the water quality

A general geochemical study has been performed within Lake Imandra situated in the industrial area in the central part of the Kola Peninsula. The impact of the main industries – mining and metallurgical enterprises - has been evaluated. The region is highly developed regarding mining and metallurgical industries. The main ones surrounding Lake Imandra are the “Severonickel” smelter, “Apatity” mining company and the Olenegorsk mining company. Analyses of water and sediment samples received from the Lake have been performed. Samples were taken in April, 1995 by Swedish and in August and October, 1995 by Russian researchers at the sampling station situated between Great and Yokistrovskaja Imandra. Water samples were collected down to a depth of 30 m, every second meter down to 24 m depth and thereafter every meter down to the sediment. The length of the sediment cores was 19 cm. Analyses of the water column show high concentrations of trace elements representing the main pollutants. These enter the lake from mines and smelters via wastewaters and atmospheric deposition. Interpretation of the sediment core suggests that the mining and metallurgical industry has a significant influence on the composition of the sediments and waters of Lake Imandra. Maxima and minima in metal concentrations coincide with peaks and recessions of the industry production. The main elements of this investigation were the main pollutants coming from the major industrial plants. The distribution of trace elements is more controlled by the natural Mn cycle than by the Fe cycle. Trace metals released from Mn and Fe oxyhydroxides in the bottom water later form sulfides in the S-rich zone, several cm below the sediment interface. In this way Ni, Cu, Co, Mo, etc. are fixed in the sediments. The chemical conditions of Lake Imandra have changed under the high anthropogenic load, and a release of elements from the sediment to the water column can be a possible future scenario.Validerat; 20101217 (root