A Paleolimnological Perspective on Arctic Mountain Lake Pollution

The chemical composition of sediments from the Arctic mountain Lake Bolshoy Vudjavr, situated in the western part of the Russian Arctic zone, was studied. The lake has been under intense anthropogenic load for more than 90 years since the development of the richest apatite-nepheline deposits in the world started. A 27 cm thick sediment core was sampled in the central part of the lake at the maximum depth of 37.4 m. The concentrations of more than 50 elements were analyzed by the mass spectral method, ICP-MS. The lake sedimentation rate established from the change in the content of the radioactive isotope Pb-210 was 2.3 mm/yr. The effluent from apatite-nepheline production and atmospheric fallout enrich the sediments of Lake Bolshoy Vudjavr with alkali and alkaline earth metals, N, P, Mn, Fe, Al compounds, rare earth elements, and trace elements (Sb, Cu, Zn, Pb, Bi, Nb, Ta, Th). Analysis of the forms of elements in the lake sediments showed that the studied elements are mainly found in stable fractions-mineral, acid-soluble, and associated with organic matter. The pollution of the sediments of Lake Bolshoy Vudjavr was assessed by the integral index PLI (Pollution Load Index) and CF (contamination factor). The PLI value sharply increased after the "Apatite" Plant had been launched and a large amount of wastewater from the mines had been released into the lake. The highest PLI values were detected in the sediment layers accumulated during the period 1990s-2000s. Sb (18.2), P (10.3), Sr (7.8), and La (6.0) have the maximum CF values among all the studied elements.