Atmospheric transport is believed to be the most important transport route for volatile and semi-volatile persistent pollutants into the Arctic (AMAP 2004). In the Barents region, data on atmospheric pollution from the Zeppelin mountain atmospheric research station (Ny-Ålesund, Svalbard, Norway) has shown a significant decrease in pollutants during the past decade (Figure 4.4.4).
However during the past 4 years, levels of hexachlorobenzene (HCB) at the Zeppelin station have been increasing again (Hung et al. 2009, Figure 4.4.5). This substance was formerly used as a fungicide, but is today released into the environment as by-product of various industrial chemical processes. Increase is also found in levels of ΣPAH in 2007 (Figure 4.4.6).
This feature is only observed at the Zeppelin station. No similar trends are reported from other Arctic atmospheric monitoring sites (e.g. Alert, Storhofdi, Pallas). The increasing concentration levels may be explained by increased evaporation of previously deposited HCB from the open ocean along the western coast of Spitsbergen (Svalbard, Norway) which has been ice-free during the past four years, including the winter seasons (2005-2008). Although there has been a dramatic decrease in sea ice also in other parts of the Arctic, a permanent all year round ice-free situation at 80º N latitude is exceptional to-date. Therefore, this signature could be interpreted as a possible direct signature of regional climate change on the POP distribution in the environment around the Barents Sea. Similar trends were seen in Zeppelin air samples for middle chlorinated polychlorinated biphenyls (penta- to hexa-chlorinated CBs) and dichlorodiphenyltrichloroethane derivatives (DDT). Regarding DDT, the re-introductions as insecticide in the tropic regions for Malaria control purposes and the related increased frequency of transport episodes from primary sources (direct application in agriculture) in low latitudinal source regions may also contribute to the currently increasing levels in the North.
The Barents Sea also receives contaminant loads associated to boreal forests from North Eastern Russia and North America. In spring (early May) of 2006, biomass burning emissions from agricultural fires in Eastern Europe were transported to Svalbard and the Zeppelin station and record-high levels of many air pollutants, including PCB, were recorded (Stohl et al., 2007). In July 2004, about 5.8 million hectare of boreal forest burned in North America and Northern Russia, emitting a pollution plume which reached the Zeppelin station after a travel time of 3-4 weeks (Stohl 2006). Again, PCB was elevated. The strong effects on observed concentrations far away from the sources suggest that biomass burning is an important source of PCBs for the atmosphere.
Generally investigations of bottom sediments in the area reveal low levels of POPs. Data from ivestigations from 2005 shows that around the southern part of Svalbard concentrations of hexachlorcyclohexane (HCH) range from 0,27-2,26 ng/g dry weight. The increase in the relative concentration of the more stable isomer α- HCH in comparison with γ-HCH indicates a long lasting inflow of hexachlorocyclohexane into the marine environment. DDT was the predominant organochlorine pesticide in the examined bottom sediments. The concentration of DDT in bottom sediments from the studied areas varied from 0,36-1,79 ng/g dry weigh. According to the classification of contaminant levels in marine bottom sediments,(SFT 1997), investigated bottom sediments from the Barents Sea should be categorized as «moderately contaminated» by DDT. The contents of p,p-DDE isomer in bottom sediments exceeded the contents of p,p–DDT isomer at all investigated stations and indicates a prolonged transformation process of DDT into more stable metabolites. Levels of the DDT (metabolitt DDE) in sediments from the Norwegian coast of the Barents Sea are low, < 0,5 µg/kg dry weight, and corresponds to “background level”. Both data from the open sea areas and the Norwegian coast shows low levels of PCB and (0,7 -5,12 ng/ g dry weight).
For most of the monitored substances in the Barents Sea the levels of contamination are well below the limit values for human consumption.
In cod liver the levels of dioxins and dioxin-like PCB measured by Norway in 2007 were relatively high. The levels were lower in 2008, but it is too early to say anything about trends. The levels of hazardous substances in blue mussels is generally low and time trend analysis reveals that the levels are decreasing. For the other species measured the levels of hazardous substances are low (Sunnanå et al 2009).
Data from the Russian side of the Barents Sea from 2005-2008 show that the combined concentrations of organochlorine pesticides (OCs) like HCHs, HCB, DDTs, chlordanes and toxaphene and polychlorinated biphenyls (PCBs) in muscle tissue of fish did not exceed the permitted levels approved by the “Russian sanitary code for raw food products and provisions”. DDT (and its metabolites) was dominant; followed by the isomers of chlordane, HCH, and HCB. A few specific results are given in Table 4.4.3.
Residues of hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and chlordanes measured in fish muscles did not exceed 2 ng/g wet weight.. High concentrations of p,p-DDE compared to other isomers in fish muscles indicates that DDT transformation occurs over time.
Marine mammals and seabirds
POPs in animals at the top of the food web are of major concern because of the accumulating properties of POPs (See chapter Current and expected state of the ecosystem - Some aspects of possible long-term future changes in the ecosystem - Future climate change and its effects on the ecosystem and human activities). Levels of POPs in polar bears at Svalbard and Franz Josef Land are above the limits for effects on the hormone and immune system. PCB has been found in especially high concentrations (Gabrielsen 2007, Letcher et al. 2009). The trend across the Barents Sea shows increased levels of PCB from the western populations to the eastern populations, probably due to a larger long range transport of PCB substances from Europe to Svalbard and the Barents Sea area. The levels of PCB have decreased from 1990 to 2002, with a levelling out at the end of this period (Henriksen et al. 2001). Recent studies have also found newer contaminants like BFH and PFC in polar bears in the Svalbard region (Smithwick et al. 2005; Muir et al. 2006).
The level of hazardous substances in Brünnick's guillemot from the Kongsfjord and Bear Island is probably below the limit for effects on reproduction and/or survival. Analyzed samples are from 1993, 2002/2003 and 2007, and the general trend is a decrease in the level of most hazardous substances during this period (Bakke et. al. 2008).