Pollution

Glaucous gull on Svalbard. Photo: Stein Ø. Nilsen, Norwegian Polar Institute

Because they are very soluble in fat, persistent organic pollutants (POPs) readily enter food chains, especially in the marine environment. These compounds accumulate in fat deposits, a process known as bioaccumulation, and thus become more concentrated in higher organisms that prey upon lower organisms.

Highest concentrations in species at the top of food chains

The result of bioaccumulation of POPs is that the lowest concentrations are found in zoo- and phytoplankton, and the highest in species at the top of food chains, such as Arctic fox, seals, polar bear and glaucous gull.

Concentrations of hazardous chemicals vary widely

Concentrations vary widely between different Arctic species and individual animals. There may be a number of reasons for this, such as differences in degree of exposure, the ability of different animals to metabolize and rid themselves of these substances, seasonal variations, choice of prey, age, and sex. The transfer of pollutants from mother to offspring, i.e. from fish to egg, from bird to egg, or from mammal to fetus or infant, may result in differences between males and females. There are often higher concentrations of pollutants in males than in females, since they cannot rid themselves of pollutants in these ways.

The problems associated with man-made hazardous chemicals in northern areas are mainly associated with the marine ecosystem. The levels of organic pollutants in terrestrial species such as reindeer, ptarmigan and geese are very low compared to those in species that predominantly acquire their food from the ocean.

In general there are lower levels of organic pollutants in organisms found in the Barents Sea and surrounding land areas than in those found in the Baltic Sea and North Sea.

Concentrations of PCBs in polar bear, Arctic fox and glaucous gull are similar to, or higher than the concentrations that have been shown to cause biological effects in seabirds and marine mammals in the Baltic Sea and North Sea.

The biological effects of POPs may be roughly classified as biochemical, physiological/pathological and ecological effects. The most direct effects are biochemical changes in the cells of an animal or plant.

At present we have very limited knowledge of how such pollutants affect the health and survival of individual animals, i.e. their physiological and pathological effects. An animal's response to such changes can be regarded as a defence mechanism, and it is possible that effects on the individual, population or ecosystem are not seen until after the defence mechanisms are overloaded. In areas where pollution is heavy, ecologically significant effects have been observed, such as impaired reproduction in marine mammals and seabirds.

High levels of PCBs in Arctic animals

Persistent organic pollutants, particularly PCBs, are the great cause for concern as regards Arctic animals. High levels of PCBs have been found in glaucous gulls, Arctic foxes and polar bears in south-western Svalbard. This is particularly worrying since we do not know what their tolerance levels are for these compounds. PCBs may affect immune system, enzyme systems, vitamin status and hormone status, and thus impair reproductive ability.

PCB can affect reproduction

There is reason to believe that PCBs are affecting polar bear reproduction in the Svalbard area. There is no similar data for arctic birds, but studies on gulls and terns near the Great Lakes in the USA have shown that PCB levels and immune-, vitamin- and hormone status are clearly correlated.

More animal studies needed

We still know far to little about how organic pollutants affect animals such as polar bears and seabirds. To learn more we need to continue studies on the effects of pollutants on the chemical composition of animal cells and physiological status (i.e. the immune system), enzymes and hormones, and combine such studies with studies of reproduction and behaviour in the same species. The results will be important in revealing the critical tolerance levels for pollutants in different organisms under Arctic conditions.

Several of the pollutants that impose a threat on animals in the polar regions are transported with winds, ocean currents and sea ice from industrial areas at more southerly latitudes.

Irresponsible or excessive use of pesticides contributes to the high levels of pollutants that are found in polar bears and other species. Most countries no longer use PCBs, but as a results of their slow degradation and the fact that emissions have continued for many years, the compounds are still finding their way into Arctic ecosystems. New chemical compounds are also being transported to the Arctic ecosystems and end up in polar bears.

If we want to keep healthy populations of seabirds and marine mammals in the Arctic, we must ensure that pollution levels remain low. Purposeful international efforts are underway to stop emissions of persistent organic pollutants, or POPs. These are a group of persistent, fat-soluble, organochlorine pollutants.

Under the Convention on Long-range Transboundary Air-Pollution, a protocol on POPs was signed by 36 European countries in 1998 and ratified by Norway on 16th December 1999. In accordance with the POPs protocol, these countries will attempt to stop emissions of about 16 POPs, including PCB, aldrin, dieldrin, chlordane, DDT, mirex and toxaphene. PCBs are no longer in use today and emissions from western countries have almost ceased. 

A global convention on persistent organic pollutants (POPs) was signed in May 2001. The convention calls for nations to work to eliminate several POPs. The use of DDT is subject to restriction under the convention.