Flow of heavy metals (Ni and Cu) in the catchment area of a subarctic lake

Abstract

This paper considers methodological approaches to estimating the flow, balance, and accumulation of heavy metals (HMs) in a lake under conditions of long-term air pollution. Using the example of Chunozero Lake in the Lapland State Biospheric Reserve in Murmansk region, the accumulation of HMs in sediments is estimated for over a 70-year period of activity of a metallurgical mining enterprise (GMK Severonikel). The thickness of polluted sediments in a greater part of the lake water area averages 2 cm, and the average sedimentation rate for the last 20 years is 1 mm/year. Metals accumulated in lake sediments can indicate a danger of pollution in the future, particularly if processes of lake eutrophication develop. Due to the peculiar properties of substance flow to the Chunozero, the running type of water-mass movement, and the elongated form of the lake, only about 3% of HMs that enter the catchment area accumulate in sediments, in contrast to Imandra Lake (which has the largest area), where the accumulation of HMs reaches 55% owing to the fact that they enter mainly in the composition of wastewater and the low velocities of water flow.