Evaluation of heavy metals (Ni and Cu) balance of the water-shed area of subarctic lake (case study of the Chunozero lake)

A methodological approach to estimation of balance and accumulation of heavy metals in a lake in conditions of long-term air pollution has been considered. On the example of the Chunozero Lake the estimation of heavy metals accumulation in sediments for more than 70-year period of activity of the mining enterprise ("Severonickel") and the Lapland State Biospheric Reserve has been carried out. It has been found out that thickness of the polluted sediments on a greater part of the lake water area averages 2 cm, and average sedimentation rate for last 20 years equals to 1 mm/year. The metals accumulated in lake sediments can represent danger of pollution of water column in future, especially during processes of lake eutrophication.