Chemical and radioactive contamination

Pollution—in the form of persistent organic pollutants, heavy metals (mercury, cadmium, and lead), pesticides and herbicides, radioactive compounds, and other toxic substances—is detectable in virtually every part of the Arctic. Much of this chemical burden originates from industrial activity and fossil-fuel burning in Europe, North America, and China. Air masses circulate pollutants to the Arctic, particularly in winter and spring. This can occur surprisingly fast: pollutant discharges in Europe, for example, can reach far northern latitudes in a matter of days. Contaminants are also borne in ocean and river currents, but more slowly.

Considerable pollution also is generated within the Arctic region. Sources include military installations, mining and metals manufacturing sites, electrical power plants, and facilities for waste disposal. The exploitation of large gas and oil reserves has caused significant environmental damage on land and sea, from blowouts, tanker spills and leakages. Radioactive isotopes occur widely in Arctic marine sediments and soils as a result of fallout from atmospheric weapons testing and the 1986 Chernobyl nuclear power reactor accident, military accidents, and discharges from European reprocessing plants. And, industrial pollution—particularly from minerals processing—has generated acid rain, decimated forested areas, and created long-lasting smog known as Arctic haze.

Cold conditions in winter enhance the settling out of airborne contaminants to land and water. Then, as temperatures warm, contaminants are reactivated and distributed by water from melting ice across the landscape, often to areas of high biological productivity, such as coastal seas and river estuaries.

Most of these harmful chemicals resist breakdown or excretion from animal bodies, so concentrations intensify with each link in the food chain from prey to predator. Top predators, including seals, polar bears—and ultimately humans—accumulate excessively elevated levels in their fat. But animals lower down on the food chain are also affected. For instance, some of the highest values of cadmium ever recorded in birds have been found in ptarmigan from northern Norway and Canada’s Yukon Territory.

The widespread uptake of mercury has been a particular concern over the past two decades. Researchers have measured some of the highest known levels of mercury industrial PCBs, and other persistent organic chemicals in Arctic residents who consume seal and whale meat. These toxic substances interfere with immune systems, development, behavior, and reproduction in birds, fish and mammals.

In recent years the environmental levels of some contaminants have fallen as a result of bans and restrictions on their usage and global progress in curbing industrial emissions. This has gradually reduced human exposure. However, newer industrial compounds are now on the rise. For example, Canadian scientists have found that levels of PBDEs (flame-retardant chemicals) have been doubling every four to five years in ringed seals. PBDEs are present in countless industrial and consumer products and are known to have potent effects on thyroid and other physiological functions.

Oil pollution also has been a growing problem over the last 30 years and it is becoming more prevalent as the expansion of petroleum exploration takes oil companies into increasingly remote areas on land and offshore. Decades-old pipelines that transport oil over thousands of kilometers are deteriorating, and leaks and spills are increasing. Air pollution and wastewater from oil-field activities, plus frequent small spills of oil and other chemicals, combine to spread heavy metals, nitrogen oxides, and hydrocarbons over the development area and beyond.