The Pasvik River flows from Lake Inarijärvi into the Arctic Ocean. It is regulated by seven hydropower plants, and has no remaining natural rapids or waterfalls. Today the river consists of lakes and artificial reservoirs linked by short river sections. The environmental impacts of the Pechenganikel mining and metallurgical industries are evident in the Pasvik watercourse. Close to the emissions sources the concentrations of heavy metals in the water, sediments and fish are high. The pollutants reach the upstream sections of the Pasvik River only by air and therefore concentrations of harmful substances are lower there.
The environmental impacts of the Pechenganikel mining and metallurgical industries are clear in the water quality of the Pasvik River. The lower section of the Pasvik River is loaded by harmful substances carried by wastewater and air. The wastewater of the Nikel mine and smelting plant are conducted via the River Kolosjoki into Lake Kuetsjärvi, and into the Pasvik watercourse. The concentrations of copper, nickel and sulfur compounds in the water are very high close to the emission sources. Pollutants reach the upper Pasvik River only by air. The prevailing wind direction from the south-southwest bring airborne pollution load more often to the lower parts of the river.
The nickel concentrations of the water only fluctuate slightly in the waters upstream from Petšenganikel combine, but in the downstream sections they increase immediately after the pollution source. Half a kilometer away from the wastewater discharge pipe the nickel concentrations can be up to five hundred times more than at the monitoring point in the Finnish side of the Pasvik River. The majority (80 %) of nickel emissions are directed straight into the water.
With copper the difference between the upstream and downstream sections is smaller as the majority (90 %) of copper emissions are carried to the waters by air and are therefore dispersed more evenly into the environment. The nickel content of the water has increased since the mid-1990s, and the copper concentrations and amount of sulphur compounds ending up in the water have remained almost at the same level.
In addition to nickel and copper emissions, industry also emits heavy sulphate emissions. Just like the nickel emissions, these are at their strongest concentrations at the survey station of the River Kolosjoki. The effects of sulphates on the water quality of the Pasvik River decreases further downstream towards the sea.
The sulphur dioxide emissions of the Pechenganikel cause the risk of acidification in the Pasvik watercourse. The water of the main channel of the river does, however, have a relatively high buffering capacity, so it endures acidic fallout well. One of the reasons for this can be the bedrock and soil factors, but the alkaline fly ash of the emissions also has an impact. The ash falls on the soil and watercourses of the most contaminated area, i.e. also the main channel of the Pasvik River. No signs of acidification have been detected in the river.
The water quality of the Pasvik River is also affected by the sparse population of the area. A visible impact of housing on the water quality can be seen only in the downstream sections, in the waters close to large settlements. However, there is no risk of these nutrient-poor northern rivers becoming eutrophied as the concentrations of nitrogen and phosphorus in the water are very low and fluctuate in an almost natural seasonal rhythm.
In the studies on water, sediment means the layered earth that has drifted and fallen out to the bottom of a water body. Sediments are usually formed on the bottoms of seas, lakes and rivers.
By analysing sediment layers, information may be obtained on the loading on the waterways and its fluctuations in the long-term.
For instance, sediment studies are used to identify changes in the state of waterways, as well as climate trends during different periods.
samples of the Pasvik River have been analyzed, for instance, for the concentrations of various elements and the placement of them in the layers representing certain time periods. High concentrations of heavy metals, such as copper, nickel, arsenic and cobalt are the clearest indicators of pollution. In addition,
persistent organic pollutants
Persistent organic pollutants (POPs) are harmful substances, which are degraded extremely slowly in the natural processes. They are capable of long-range aerial transport and bioaccumulation.
Some POPs are formed in natural conditions but most of them are anthropogenic. For example, the insecticide DDT is a persistent organic pollutant
Polyaromatic hydrocarbons (PAHs) are harmful substances, which are formed by incomplete combustion. They are carcinogenic, mutagenic and teratogenic.
PAHs are one of the most widely dispersed groups of harmful organic substances.
are also notable pollutants.
The environmental impacts of the Pechenganikel mining and metallurgical industries are clearly evident in the sediments of the Pasvik River. Heavy metals bound to small particulate matter sink slowly to the bottom, becoming part of the sediment of the river. The concentrations of heavy metals and organic compounds in the sediment are high near the emission sources and they diminish further downstream. For example, the nickel concentrations in the sediment of Lake Kuetsjarvi are around a hundred times greater than in reference lakes. The concentrations of many persistent organic pollutants and polycyclic aromatic hydrocarbons are significantly higher in the sediments of the downstream sections of the Pasvik River than elsewhere in Northern Norway. Increase in concentrations of
Chalcophile elements combine readily with sulfur (sulfides) instead of oxygen (oxides).
Chalcophile elements include mercury, cadmium, arsenic lead and zinc, among others.
(Pb, Cd, As and Hg) was observed in the upper layers of bottom sediment of the lakes in upstream sections of the river.
Bottom sediments can provide a time series of the concentrations of pollutants. For instance, the concentrations of persistent organic pollutants and heavy metals are higher in the surface sediment of Lake Kuetsjarvi than in lower sediment layers, which indicates that concentrations have become elevated for the past few decades. There is no noticeable decrease of heavy metal concentrations in the surface of the bottom sediments even though the Pechenganikel has reduced the heavy metal discharge into Lake Kuetsjarvi. The time before the existence of the emission sources may be studied at the depth of over twenty centimeters.
In the upstream sections of the Pasvik River the pollutant concentrations in sediments are at the same level as in the other water bodies of the border area, as the pollution levels are only affected by airborne fallout.
Pasvik River phytoplankton is characterized by high diversity. The different reaches have different phytoplankton communities though diatoms, blue-green algae (cyanobacteria) and yellow-green algae were the most abundant. The species composition is, however, changing due to climate warming and eutrophication processes. The community was formerly dominated by diatoms and yellow-green algae, whereas now the proportions of green and blue-green algae are becoming larger.
Zooplankton in an important link in the food chain from bacterio- and phytoplankton to benthic invertebrates and fish and they can be used in evaluating the state of the environment. Zooplankton community of the Pasvik River consisted of rotifers, cladocerans and copepods and the detected species were typical of oligotrophic, cold lakes and rivers. Small rotifers are the main group quantitatively but in biomass cladocerans dominate. Cladocerans and copepods are important as prey of planktivorous fish. Also Eudiaptomus-copepods, which are sensitive to pollution, can be found in many of the reaches of the river.
Macrophytes are aquatic plants that live completely or partly in water. Macrophyte communities can be used to estimate the ecological state and the impacts of water level regulation in different water bodies. Regulation-related effects on the macrophytes in the Pasvik River seem to be small even though regulation has turned the river into a continuum of short riverine sequences and reservoirs. The water level fluctuations are very small and the winter drawdown is insignificant, which is probably the reason that the macrophyte community is very close to a natural one. For example, sensitive species such as lake quillwort (Isoetes lacustris) and alternate-flowered water-milfoil (Myriophyllum alterniflorum) grow in the river.
The macrophyte community of the Pasvik River is very diverse compared to most of the other large Norwegian rivers and the number of species indicating eutrophication is also low. The ecological state of most reservoirs is good or excellent.
In the zoobenthos community of the Pasvik River relatively many taxons are present despite the water regulation. The presence of regulation-sensitive species is enabled by stable water level conditions. Especially species that are missing in strongly regulated lakes, for example Polycentropus flavomaculatus (Trichoptera), Sialis sp. (Megaloptera) and Caenis horaria (Ephemeroptera), were found in the Pasvik River. Changes in the habitat structure (caused, for example, by flushing of sediments) are likely to affect some species, such as the burrowing mayflies (Ephemeroptera). Also, species which are more or less attached to the substrate (for example, some net-spinning caddisflies, Trichoptera) may suffer from alterations, because they are unable to retreat deeper if the water level lowers. The depth of water in the littoral zone may be one of the factors affecting the sensitivity of the benthos to water level changes.
More frequent water level changes can decrease the amount of sensitive species in the Pasvik River due to possible climate change. It is recommended to keep the water level changes in minimum to preserve the ecological quality of the Pasvik River.
The Pasvik River benthos community is also affected by the Pechenganikel mining and metallurgical industries. For example, the taxonomic diversity of littoral benthos and the number of indicator groups (EPT) increase with distance from the source of pollution.
The Pasvik River also has lake-like water reservoirs in which there are zones of deeper water. In these soft-bottom habitats the variety of zoobenthos is low. Chironomids and oligochaetes prevail in the communities and other benthos groups are rare.
The environmental impacts of the mining and metallurgical industries are evident in the species community of the Pasvik River. The impacts are more significant in the water bodies located close to industrial areas, such as in Lake Kuetsjarvi, where, for instance, heavy metals have detrimental effects by accumulating in the body of the fish. The fish populations are also affected by persistent organic pollutants, which accumulate in the adipose tissues of animals and become enriched on higher levels of the food chain.
Different fish species react differently to heavy metals. Whitefish have been noticed to be especially susceptible to accumulating nickel and cadmium. Copper is accumulated in the liver of whitefish, whereas the highest concentrations of nickel can be found in the kidneys. Mercury has been found to especially accumulate in the muscle of perch and pike. As a consequence of such exposure to heavy metals, fish may suffer from deformed reproductive organs, kidney stones, and other malformations. Many species of fish in Lake Kuetsjarvi also have malformations in different tissues, gills and internal organs, as well as underdeveloped gonads.
In the most polluted areas changes in the life cycle of the fish have also become evident. Fish become sexually mature earlier, remain smaller and have shorter longevity. This is particularly true for whitefish.
In the downstream sections of the Pasvik River further away from the smelting plant the heavy metal concentrations in fish, and consequently the malformations, decrease. The nickel concentrations in the kidneys of whitefish are reduced quickly as the distance from the smelting plant is increased. Similarly, the impact of pollution in the upstream sections of the river is not as clear.
The structure of fish communities of many reaches of the Pasvik River are also changing regardless of their distance from the pollution source. The original communities have consisted mainly of salmonids and whitefish, but due to changing climate and anthropogenic stress the proportions of perch, pike, smelt and cyprinids are growing.
The border area has long traditions of fishing for domestic use, recreation and as a livelihood. The annual catch of fish over the past few decades has been 200 – 600 tons. There is still very little information available on the cumulative effect of localized high heavy metal and persistent organic pollutant concentrations in fish to people, and more studies should be commissioned on the matter. In studies the concentrations of persistent organic pollutants have not, however, exceeded the highest permitted limit stipulated for fish to be used as nutriment.
The Pasvik River hydropower stations also have an impact on the fish populations. The dams hinder migration and have changed the former river system into a series of consecutive lakes and reservoirs. This has degraded and reduced the main spawning, nursery and feeding areas for brown trout and grayling severely. The abundance of these species was reduced whereas typical lake-dwelling fish (whitefish, perch and pike) benefitted. Perch also benefits from climate change impacts e.g. increasing temperature, and the proportion of perch in the fish communities has grown. Higher water temperature also probably increases larval and juvenile growth of whitefish and vendace, the latter being an invasive species in the Pasvik watercourse.
The newest report on the chemical status of the Pasvik River is the Pasvik Water Quality until 2013 which examines the trends in water quality during 2000–2013. The previous status report, Pasvik Water Quality Report, included the results of water quality monitoring of 2000–2009.