Trends for contaminants in the Arctic

The levels of contaminants in the Arctic vary in both time and space. Contaminants that are transported in the atmosphere follow the seasonal fluctuations of the air masses, and levels therefore vary through the year. The levels of other contaminants vary as a result of efforts made by management authorities through international conventions, for example, and we can consequently see declining trends of contaminants in the Arctic.

Organic pollutants

Time trends for organic pollutants in the Norwegian part of the Arctic vary considerably, depending upon the substances and where they are measured. The air measurements show a rising trend for HCB, varying trends for PCBs and declining trends for HCH, [tooltip id={chlordanes}]chlordanes[/tooltip] and DDT. No trends have been observed for PBDE, PFAS or TBA, which have been monitored in the air since 2006.

Compared with other parts of the Arctic, high PCB levels have been measured in the air and in lake sediments from Svalbard. The PCB levels in wildlife from Norwegian arctic areas show a declining trend. However, PCBs are still the predominant contaminant in the Arctic. Since PCBs degrade slowly, they will remain in the environment for many more decades. The chlorinated herbicides show more varying trends, but the main trend seems to be declining levels. Groups of brominated compounds like PBDE and PBB have been observed to be declining, whereas other brominated compounds like α-HBCD are rising. The time trends for fluorinated compounds in the Arctic are not clear and vary from one to another.

Management measures such as bans and phasing out lead to reductions in emissions and transport. Substances like PCBs and chlorinated sprays are decreasing because bans on their manufacture and use have been introduced, whereas concentrations are increasing for substances that have not been banned internationally, for instance HBCD and some of the fluorinated compounds. The "new" contaminants which are discovered in the Arctic give grounds for concern and show that more substances than the traditional persistent organic pollutants (POPs) have a potential for long-range transport. The concentrations of polluting substances which have been banned and phased out are expected to decrease in the future. However, the manufacture and use of new compounds is constantly increasing and these may affect the arctic environment.

Heavy metals

The heavy metals, cadmium, mercury and lead, are regarded as challenging for arctic areas. Mercury discharges have been reduced in North America and Europe since the 1990s, whereas they have increased greatly in Asia. The reduction in the use of leaded petrol has been very effective in reducing lead pollution. Changes in the concentration of cadmium and mercury have not been measured at the Zeppelin Station at Ny-Ålesund in Svalbard since measurements started in 1994, but lead has declined by 30 %. There are lower quantities of heavy metals in lake sediments from Svalbard than from mainland Norway. Mercury and cadmium levels in wildlife from Svalbard are generally lower than from other parts of the Arctic.

Radionuclides

De viktigste kildene til menneskeskapt radioaktivitet har vært globalt nedfall fra atmosfæriske kjernefysiske våpentester, utslipp fra gjenvinningsanlegg i Europa og Tsjernobylulykken. Utslipp fra alle atomanlegg til The most important sources of anthropogenic radioactivity have been global fallout from nuclear weapon testing in the atmosphere, discharges from recycling plants in Europe and the Chernobyl disaster. On the whole, discharges from all nuclear plants to northern European waters have been reduced since the early 1990s, and levels of radioactivity are continually declining. The expected trend in the years to come is that the levels of anthropogenic radioactivity will continue to sink.

Geographical trend in wildlife

The geographical trends found in the Arctic fox corresponds with the trends found in the polar bear, with the highest contaminant values in East Greenland and Svalbard, moderate ones in Canada and the lowest ones in Alaska. Recent studies have shown that the levels of contaminants in arctic foxes are strongly related to where in the food chain they find their food and the proportion of marine and terrestrial food items in their diet, that is to say where they spend most of their time and what they eat. Results from Svalbard show that the levels of contaminants are highest in arctic foxes which find food high in the marine food chain.

The geographical differences in arctic foxes can also be related to the two different types of habitat arctic foxes live in, inland and coastal habitats. Foxes which have mostly eaten animals living on land (for instance, ptarmigan and reindeer) have lower PCB levels than those which have eaten animals living in the sea (for instance, seals). The high levels of contaminants in arctic foxes in Svalbard and Iceland can be explained by them having a more marine diet than those in Canada and Alaska.