The Kola Scientific Center studied the state of one of the most polluted water bodies in the Arctic

The Kola Scientific Center studied the state of one of the most polluted water bodies in the Arctic
The Kola Scientific Center studied the state of one of the most polluted water bodies in the Arctic
Anonim

Scientists of the Kola Science Center from the Institute of Industrial Ecology of the North have summed up the results of long-term studies of the state of the border lake Kuetsjärvi, which is rightfully considered one of the most polluted water bodies in the Arctic. For about 30 years, scientists have been conducting a comprehensive study of the lake, on the shore of which a copper-nickel plant operates. It creates specific conditions for the development of living organisms in the reservoir, including plankton, benthos and fish communities.

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The results of the work of Russian ecologists have been published in the international journal Environments. Since 2018, research has been supported by a grant from the Russian Foundation for Basic Research, and since 2019 - by a grant from the Russian Science Foundation. Lake Kuetsjärvi is located in the northwest of the Murmansk region, a few kilometers from the Russian-Norwegian border. An urban-type settlement Nikel was built on the shore of the lake, as well as smelting shops, mines and a slag storage facility of the Kola Mining and Metallurgical Company (Pechenganikel site).

The enterprise has been operating on the shores of Kuetsjärvi since the middle of the last century, supplying harmful emissions to the lake ecosystem through the Kolosjoki River, by air and through the soil cover of the lake's catchment area polluted around it. Scientists have established extremely high concentrations of nickel, copper, cobalt, zinc, cadmium, mercury and arsenic in water and in the surface layer of Kuetsjärvi bottom sediments.

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Since the beginning of observations of the state of the lake in 1989, the content of Ni and Cu has tended to grow steadily. The behavior of these metals is similar in the sediments of the reservoir. In the uppermost layer of bottom sediments of the lake (0-1 cm), the Ni content can be 130 times higher than the background level (layer 22-23 cm).

In water, the concentration of this metal is even higher - 200 times higher than the background of the region. At the same time, over the past 30 years, the general level of water mineralization in Lake Kuetsjärvi has decreased and, on the contrary, the content of organic carbon has increased (the process of eutrophication), which is also partly related to the anthropogenic impact on the reservoir.

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Environmental studies show that as a result of chemical pollution in recent years, there have been major changes in the communities of living organisms of the border lake

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For example, in plankton (organisms living in the water column), the dominant plant groups changed: the proportion of green algae and cyanobacteria increased, the proportion of diatoms and golden algae, which are most typical of the clean natural waters of the Arctic, decreased. At the same time, the total biomass of algae in Lake Kuetsjärvi increased due to species that are resistant to the negative effects of chemical pollutants.

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The increased levels of metals in the bottom sediments of Lake Kuetsjärvi affected changes in the composition of benthic organisms (living on the bottom and in the mud). Thus, over the past 20 years, the total number of benthos species has halved. Mainly, those species that are considered to be the most sensitive to anthropogenic pressure (for example, molluscs and water beetles) have disappeared. On the other hand, the share of small-bristled worms, which are close relatives of earthworms known to all, has increased. Scientists also associate the latter fact with anthropogenic influence on the reservoir, in particular, with a significant accumulation of phosphorus in the upper layers of bottom sediments.

Changes in the structure of planktonic and benthic organisms naturally led to changes in more highly organized creatures - fish. Scientists note that during the continuous observation period in the reservoir, the share of whitefish and pike in catches has decreased, and the share of perches and vendace, which earlier artificially entered Kuetsjärvi through the Pasvik River, increased.

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However, the changes in the fish population of Kuetsjärvi are not as sharp as compared to the changes in plankton and benthos and are probably associated not so much with lake pollution as with general changes (for example, climatic) in the Arctic zone. In addition, scientists have established changes in the biological characteristics of whitefish, pike and perch, but whether they are directly related to the pollution of the lake can only be shown by further research.

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Monitoring of the state of Lake Kuetsjärvi will be continued by the staff of the Institute for Problems of Industrial Ecology of the North. This becomes especially important in connection with the closure of the smelting shop and along with the plans to form a tourist cluster in the Nikel region, because the most important condition for the successful development of tourism in this area is a favorable ecological situation. It is obvious that the closure of production will exclude the flow of pollutants into natural ecosystems, but at the same time, it can cause significant changes in the chemistry of waters, the consequences of which are still very difficult to predict.

In addition, contaminants, including potentially toxic metals, from contaminated soil will enter Lake Kuetsjärvi for many decades to come. Also, due to possible changes in the chemical composition of the water, the manifestation of the effects of secondary pollution of the lake due to bottom sediments, from which metals can flow back into the aquatic environment, is likely. It is obvious that all these processes can again affect the changes in the structure of living organisms in Lake Kuetsjärvi, just like in the entire ecosystem as a whole.

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