Anthropogenic impact: Pollution

The report given represents some information on the current level of pollution in certain elements of the Barents Sea ecosystem. Samples were collected during a cruise of RV “Fridtjof Nansen” in February 2016. Preparation and analysis of samples were carried out in accordance with ICES guidelines. In the present report, we present cruise data collected in different fishing areas of the central and the southern parts of the Barents Sea. The objects analysed are the following: water (surface and bottom layers), bottom sediments (upper layer), and commercial fish species (muscles and liver). PINROs sampling stations for sediment, seawater and fish are shown in Figure 3.9.6.1a and b.

Figure 3.9.6.1a. PINROs sampling stations for sediment and seawater in 2016. Figure 3.9.6.1b. PINROs sampling stations for fish in 2016.

IMR carries out sample collection for thorough investigations of the levels of contaminants in seawater, sediments and marine biota in the Barents Sea every third year. The last time was in 2015, when samples were collected from RV “Johan Hjort” and RV “G.O. Sars” in August and September. The sampling stations are shown in Figure 3.9.6.2. The analysis includes different hydrocarbons, persistent organic pollutants (POPs) (PCB, DDT, HCH, HCB) and radionuclides. Monitoring of radionuclides focuses on the most abundant anthropogenic (man-made) gamma-emitting radionuclide cesium-137 (Cs-137), but the levels of other anthropogenic radionuclides like strontium-90 (Sr-90), plutonium-238 (Pu-238), plutonium-239,249 (Pu-239,240) and americium-241 (Am-241) are also determined in a selection of samples. Monitoring of radionuclides is performed in close cooperation with the Norwegian Radiation Protection Authority (NRPA) within the national monitoring programme “Radioactivity in the Marine Environment” (RAME). Monitoring of organic contaminants is performed in close cooperation with NGU (The Geological Survey of Norway) and National Institute of Nutrition and Seafood Research (NIFES).

In addition to the triennial sampling cycle, samples of cod are caught along the coast of Finnmark and in the Bear Island area twice a year, in order to monitor the levels of Cs-137 in muscle tissue of this important commercial species. The results are part of a time-series from around 1990. Further, IMR investigate once a year the levels of radioactive contamination near the wreck of the Russian nuclear submarine “Komsomolets”, which sank in 1989 in international waters in the Norwegian Sea 180–190 km south-southwest of Bear Island at 73°43’16’’N and 13°16’52’’ E. Samples of surface seawater (approximately 500 L) and bottom seawater (approximately 500 L) are collected with a CTD-rosette multi bottle sampler with large (10 L) water samplers. Sediment samples are collected with a sediment sampler of the type “Smøgen Boxcorer”. The samples are analysed for a range of radionuclides (e.g. plutonium-238, plutonium-239,240, cesium-137 and strontium-90) at IMR and NRPA.

3.9.6.2

Figure 3.9.6.2. IMRs sampling stations in 2015 for sediment (blue circles), seawater (green triangles) and fish and other biota (red triangles).

Organic pollutants and metals

Average PAH concentration in clean areas of the Antarctic (20 ng/l) could be used as a global background level for assessment. In surface layer of the Barents Sea, total PAH content fluctuated in the range of 8–51 ng/l with the average concentration of 21 ng/l and in the near bottom layer – in the range of 8–47 ng/l with the average concentration of 22 ng/l (Figure 3.9.6.3a).

The highest total PAH concentrations are revealed in the surface layer at the Stations 8 and 13 and in the near bottom layer – at the Station 9. Compared to the data obtained during the same period in 2013, 2014, and 2015, current data shows reduction in median and extreme values of PAH content in seawater. Based on a classification given by the Norwegian Environment Agency (MD), PAH concentrations in surface and near bottom layers of the examined fishing areas of the Barents Sea fall into the category “slightly polluted”.

Analysis of upper sediment layer samples showed the highest polycyclic aromatic hydrocarbons (PAH) content in sediments at the Station 8 of the Kola Section, which amounts to 285 ng/g dry weight (Figure 3.9.6.3b). Content of PAH in sediments of the explored Barents Sea areas, as well as content of the most famous carcinogenic PAH component – benzo[a]pyrene, did not exceed background levels of <300 and <10 ng/g dry weight respectively.

Figure 3.9.6.3a. Concentration of polycyclic aromatic hydrocarbons (PAHs) in seawater analysed by PINRO. Figure 3.9.6.3b. PAH content in bottom sediments.

Total content of α-, β- and γ- hexachlorocyclohexane (HCH) isomers in analysed sediments varied from 0.4 ng/g to 6.0 ng/g with the average concentration of 2.5 ng/g dry weight (Figure 3.9.6.4 a). This level is higher than the level estimated last year (last year the average value amounted to ~1 ng/g dry weight). According to the Norwegian MD classification, concentration of γ-HCH isomer (lindane) in analysed sediments fell into the category “slightly polluted” (<1.1 ng/g dry weight).

Total content of dichlorodiphenyltrichloroethane (DDT) metabolites in investigated sediments of the Barents Sea varied from 0.5 ng/g to 1.7 ng/g with the average concentration of 0.8 ng/g dry weight. (Figure 3.9.6.4b). According to the MD classification, content of ∑DDT at the Station 2 corresponded to the background level (<0.5 ng/g dry weight), the rest stations fell into the category slightly polluted” (0.5–20 ng/g dry weight).

Figure 3.9.6.4a. Hexachlorocyclohexane (НСН) [∑(α-НСН, β-НСН, γ-НСН)] content in bottom sediments. Figure 3.9.6.4b. Dichlorodiphenyltrichloroethane (DDT) [∑(о,р'-DDE, р,р'-DDE, о,р'-DDD, р,р'- DDD, о,р'-DDT, р,р'-DDT)] content in bottom sediments.

The lowest concentrations of copper, zinc, nickel, chromium, manganese, iron, lead, cadmium, arsenic, and mercury were indicated in silty sands at the Stations 29 and 56 (Figures 3.9.6.5 a and b), where sand grading <0.063 mm accounted for about 15% and content of organic carbon was 0.5%. The highest concentrations of mentioned heavy metals and arsenic were indicated in bottom sediments at the Stations 8–10 in clayed silt, where percentage of fines (0.063 mm) was 60–70% and organic carbon content accounted for 2%. According to the Norwegian MD classification, content of lead and nickel in upper sediment layer at the Stations 3, 6–10, 47 fell into the category “slightly polluted” and did not exceed background levels at the rest stations (<30, <30 и <70 µg/g dry weight respectively). Concentrations of nickel and lead are shown in Figure 3.9.6.5 a and b.

Figure 3.9.6.5a. Nickel content in bottom sediments. Figure 3.9.6.5b. Lead content in bottom sediments

The highest content of HCH isomers was indicated in muscles of Jelly wolfish (4.53 ng/g wet weight) caught at the Station 5 (Figure 3.9.6.6a). Also the highest content of DDT isomers was revealed in muscles of Greenland halibut from the same area (9.88 ng/g wet weight, Figure 3.9.6.6b). According to the classification adopted by the Norwegian Environment Agency (MD), mean value of total HCH and DDT isomers concentration corresponded to the category “moderately polluted” (0.5–2.0 ng/g and 1.0–3.0 ng/g wet weight respectively).

High content of HCH isomers is indicated in liver of American plaice caught at the Station 62 (8.46 ng/g wet weight) and the Station 13 (7.71 ng/g wet weight). According to the Norwegian classification, average concentration of HCH isomers in liver of cod corresponded to the category “slightly polluted” (<50 ng/g wet weight).

Figure 3.9.6.6a. Average concentrations of hexachlorocyclohexane (HCH) in muscle of fish Figure 3.9.6.6b. Average concentrations of hexachlorocyclohexane (HCH) in liver of fish

Total content of polychlorinated biphenyls (PCBs) fluctuated from 1 to 12 ng/g wet weight in muscles of examined fish and from 6 to 470 ng/g wet weight in liver (Figures 3.9.6.7 a and b). The highest concentration of PCB was indicated in liver of cod taken at the Station 15–474 ng/g wet mass, that fell into the category “slightly polluted” of the Norwegian classification (<500 ng/g wet weight).

Figure 3.9.6.7a. Average concentration polychlorinated biphenyls (PCBs) in fish muscle Figure 3.9.6.7b. Average concentration polychlorinated biphenyls (PCBs) in fish liver

Average concentration of arsenic in muscles of haddock, plaice and spotted wolfish exceeded standard of 5 μg/g wet weight. In several samples of cod and American plaice, exceeded levels of arsenic in muscles were also observed (Figures 3.9.6.8a and b). Increase in total arsenic content does not jeopardize human health as it forms stable complexes with low-molecular organic compounds and could be easily removed from the body.

Figure 3.9.6.8a. Average arsenic concentration in fish muscle Figure 3.9.6.8b. Average arsenic concentration in fish liver

Surveys over 20 years in the Barents Sea by IMR

Our results from 20 years of environmental surveys vary quite a lot. Levels of some types of contaminants are low or undetectable, whereas others are clearly present. We see, for instance, low levels of brominated flame retardants, while there often are higher levels of PCB and the pesticide DDT than of other substances. The higher we get in the food chain, the greater the concentrations of contaminants. This is as we expected.

Concentrations also increase with age in fish (Boitsov et al., 2016). Although some of the contaminants are present at higher concentrations than others, even the higher levels are usually below the maximum limits for nutritional safety (200 g/kg wet weight for the sum of six PCB congeners in liver).

Several species have been sampled consistently over time, whereas others have been sampled more sporadically. For the species under regular surveillance, we can present time-series describing changes in the contaminants over time. Levels of some substances have decreased significantly in the past 15–20 years. An example is the pesticide HCH in liver from cod in the Barents Sea (Figure 3.9.6.9). Levels of some other substances seem relatively stable, for instance PCB in liver from the same cod (Figure 3.9.6.9). North East Arctic cod is one of the most valuable commercial species in the Barents Sea and a key component in the ecosystem.

Figure 3.9.6.9. Contaminants in livers from Barents Sea cod. Data for each year represent averages from 25 fish. Levels of PCB7 (upper graph) decreased rapidly, then stabilized from the end of the 1990s, whereas the levels of the pesticide HCH (lower graph) showed relatively steady decrease throughout the study period. A similar development over time has been observed in liver of Greenland halibut (Figure 3.9.6.10).

Levels of environmental contaminants in Greenland halibut has recently received more attention, as high levels of PCBs, dioxins and mercury have been found in muscle, although differences have been observed with areas and size. Highest levels of PCB7 were found in the Norwegian Sea off the coast of Nordland (Northwest of Trænabanken and along the shelf edge), up to 100 micrograms/kg wet weight.

Figure 3.9.6.10. Average levels of PCB7 (A) and ƩHCH (B) in Greenland halibut liver from the Barents Sea.

Haddock is also a commercial important species in the Barents Sea, and levels in liver shows a similar trend in pollutant over time as observed in Arctic cod and Greenland halibut (Figure 3.9.6.11).

Figure 3.9.6.11. Average levels of PCB7 and ∑HCH in haddock liver from the Barents Sea.

Our surveys show that it is still important to monitor organic contaminants in the marine food chain and in sediment. The contaminants are transported over great distances from their original sources, and background levels are clearly detectable even in the Arctic, where there are few local pollution sources. Despite having been prohibited for several decades in many countries, some of these contaminants persist in the environment.

For some groups of substances, levels in open waters are slowly but surely decreasing, while others are maintaining stable low levels. It is important to document this development, too, and thus continue the time-series established through two decades of surveys.

Radionuclides

The most important sources for radioactive contamination of the Barents Sea are well known and include global fallout from atmospheric nuclear weapons testing during the 1950s and 1960s, river transport by the Ob and Yenisey of radionuclides originating in Russian nuclear enterprises, discharges from European reprocessing plants for spent nuclear fuel (Sellafield and La Hague) and fallout from the Chernobyl accident in 1986. Additionally, liquid and solid radioactive wastes dumped in the Barents and Kara Seas and wrecks of sunken nuclear submarines represent potential sources.

The samples that were collected in the Barents Sea in 2015 was prepared and analysed during 2016. In this report, we present results from analyses of Cs-137 in sediments, seawater and fish. The analyses of Cs-137 in seawater collected in 2015 were performed by the NRPA. Analyses of Sr-90, Pu-238, Pu-239,240 and Am-241 in seawater have also been performed by the NRPA, but will not be presented here.

Activity concentrations of Cs-137 in sediments were found to range from 1.7 to 7.7 Bq/kg (Figure 3.9.6. 12). The highest level was found in the inner Laksefjord in Finnmark, and the lowest level was found in the Central Barents Sea. The levels are low and comparable to previously reported values from the 1990s and 2000s. The contamination sources are a combination of atmospheric nuclear weapons testing, European reprocessing plants and the Chernobyl accident. The highest levels of Cs-137 in sediments in Norwegian Sea areas are found in fjords in mid-Norway. For example, the levels in the inner part of the Vefsnfjord in Nordland have varied between 200 and 350 Bq/kg for the past ten years. The contamination source is the Chernobyl accident.

Figure 3.9.6.12. Activity concentrations of Cs-137 in sediments in 2015. The average activity concentration of Cs-137 in four samples collected near “Komsomolets” (2.7 Bq/kg) is also shown.

The activity concentrations of Cs-137 in seawater collected in 2015 at the seven stations shown in Figure 3.9.6.12 range from 1.3 to 1.9 Bq/m3. These levels are low, and the results indicate that Cs-137 is relatively homogenously distributed throughout the Barents Sea. In general, levels of Cs-137 in seawater in the Barents Sea are slightly lower than the levels found in other Norwegian Sea areas. For comparison, the levels of Cs-137 in seawater in seven samples collected in the Skagerrak in 2015 ranged from 4.0 to 5.2 Bq/m3. The higher levels in the Skagerrak are due to the closer proximity to important contamination sources, namely outflowing Baltic water, containing Chernobyl contamination, and the European reprocessing plants for spent nuclear fuel, Sellafield and La Hague.

Activity concentrations of Cs-137 in common species of fish collected in the Barents Sea in 2015 are below 0.2 Bq/kg fresh weigh (Figure 3.9.6.13), and much lower than the intervention level set by the Norwegian Authorities after the Chernobyl accident (600 Bq/kg fw). To place the results into context, time-series of Cs-137 in cod along the coast of Troms and Finnmark, and in the Bear Island area from approximately 1990 until present are shown in Figures 3.9.6.14a and 3.9.6.14b, respectively. It is evident that the levels have decreased during this period, and the levels in cod in the Barents Sea have been below 0.2 Bq/kg ww (wet weight) for the past ten years. The decrease is due to reduced discharges from Sellafield and La Hague and decay of pollution from nuclear testing during the 1950s and 1960s and the Chernobyl accident 1986. In addition, the pollution is diluted in seawater over time.

Figure 3.9.6.13. Activity concentrations (Bq/kg fresh weight) of Cs-137 in common species of fish caught in the Barents Sea in 2015. The sampling stations are shown in Figure 2. Between 1 and 5 samples of each species have been analysed. For species where more than one sample has been analysed, the average is shown, and the minimum and maximum activity concentrations are shown with error bars. The uncertainty in single measurements vary between 20 and 50% Figure 3.9.6.14a. Activity concentrations of Cs-137 (Bq/kg fresh weight) in cod caught in the Bear Island area in the period 1993 to 2015. Data from NRPA and IMR. Uncertainties in single measurements are generally below 30%. Figure 3.9.6.14b. Activity concentrations of Cs-137 (Bq/kg fresh weight) in cod caught along the coast of Troms and Finnmark in the period 1991 to 2015. Data from NRPA and IMR. Uncertainties in single measurements are generally below 30%.

The Norwegian monitoring of the area adjacent to the sunken nuclear submarine “Komsomolets” do not reveal any significant leakage (Figure 3.9.6.15). Due to the depth at which the submarine lies and effect of subsurface currents, it has, however, not been possible to know how close to the wreck the samples have been collected. In 2013 and 2015, sampling was carried out using an acoustic transponder that allowed samples to be collected at a distance of approximately 20 m from the hull of the submarine. We did not find elevated levels of Cs-137 in these samples.

Figure 3.9.6.15. Activity concentrations of Cs-137 in sediments and bottom seawater collected in the area adjacent to the sunken nuclear submarine «Komsomolets» in the period 1993 to 2015.

Summary

Russia and Norway conduct monitoring in the Barents Sea according to national monitoring programs. Russia conduct monitoring every year, and Norway conduct monitoring every third year (last time in 2015).

Concentrations of polycyclic aromatic hydrocarbons (PAH) in water of the investigated Barents Sea areas exceeded global background level of 20 ng/l at several stations.

PAH and benz(a)pyrene content in bottom sediments did not exceed background levels – 300 ng/g and 10 ng/g dry weight respectively. The results show that muscles and liver of commercial fish in the Barents Sea are slightly polluted with carcinogenic PAHs.

Concentrations of organochlorine pesticides (OCP) and polychlorinated biphenyls (PCB) in water did not exceed the Threshold Limit Value (TLV) for fisheries waters that equals to 10 ng/l. Regarding dichlorodiphenyltrichloroethane (DDT) content, bottom sediments fall into the category “moderately polluted”. Concentration of PCBs in sediments of the Barents Sea corresponded to technogenic background level of 5 ng/g dry weight. Total concentrations of OCPs and PCBs in muscles and liver of examined fish were much lower than levels set out in sanitary rules and norms for sea fish in Russia.

Concentrations of metals in water were generally lower than the Threshold Limit Value (TLV) for fisheries waters. Concentrations of copper, zinc, lead, cadmium and mercury in bottom sediments of the Barents Sea conformed to background levels. Regarding nickel, chromium and arsenic content, several areas corresponded to the category “moderately polluted”. In muscles and liver of examined commercial fish from the Barents Sea, average concentrations of cadmium, lead and mercury did not exceed levels stated in sanitary rules and norms. Mean content of arsenic in muscles of several species (haddock, plaice, spotted wolfish) exceeded the level of 5 μg/g wet weight.

Activity concentrations of Cs-137 in sediments collected in the Barents Sea in 2015 ranged from 1.7 to 7.7 Bq/kg. The highest level was found in the inner Laksefjord in Finnmark, and the lowest level was found in the Central Barents Sea. The levels are low and comparable to previously reported values from the 1990s and 2000s.

Further, the activity concentrations of Cs-137 in seawater range from 1.3 to 1.9 Bq/m3. These levels are low, and the results indicate that Cs-137 is relatively homogenously distributed throughout the Barents Sea. In general, levels of Cs-137 in seawater in the Barents Sea are slightly lower than the levels found in other Norwegian Sea areas. For comparison, the levels of Cs-137 in seawater in seven samples collected in the Skagerrak in 2015 ranged from 4.0 to 5.2 Bq/m3.

Activity concentrations of Cs-137 in common species of fish collected in the Barents Sea in 2015 are below 0.2 Bq/kg fresh weigh (Figure 10), and much lower than the intervention level set by the Norwegian Authorities after the Chernobyl accident (600 Bq/kg fw).

Final Conclusions

The pollution levels have been generally low in the Barents Sea ecosystem for a long time. In the short run, no significant adverse impact of current pollution of organisms or environment would affect stocks of commercial aquatic organisms in investigated areas of the Barents Sea.

Suggestions for future indices

In order to evaluate the dynamics of pollution in the Barents Sea in future, the following indices may prove to be useful:
Bottom sediments: PAH16, Benzo(a)pyren, Cs-137 Cod and Greenland halibut (liver): PCB7 and ƩDDT
Cod and Greenland halibut (muscle): Pb, As, Hg, Cd, Cs-137 Seawater: Cs-137
We have data on all these contaminants for the past 10 years.