The polar regions are generally considered to be pristine and scarcely influenced by human activity. Thus it might be surprising that contamination of the Arctic environment should be of major concern. Nevertheless the Arctic has become contaminated by industrial, agricultural and military activities. Understanding the mechanisms involves in this contamination of a remote environment is a major scientific undertaking and has led to several international research programmes, the most notable of which is the Arctic Monitoring and Assessment Programme (AMAP). Activities include investigations of persistent organic pollutants (POPs), heavy metals, radioactivity, acidification, petroleum, climate change, biodiversity and native human populations, and were recently summarized in an assessment report (AMAP 1998). The pollution work of Tundra Northwest 1999 reported on here includes POPs and other organic pollutants and heavy metals.

There are three main ways in which contamination of the Arctic can occur:

1. human activities in the Arctic itself,
2. long-range transport via water (oceanic currents or major rivers),
3. long-range transport via air from sources further south.

Different types of pollutants may reach the Arctic via different main pathways. According to the currently most popular hypothesis, a major cause of Arctic contamination by POPs, is long-range transport via the air (Wania and Mackay 1996), even if transportation via ocean currents or large rivers cannot be ignored. At the local level, military activity has also led to very high levels of contamination by some organic pollutants.

Trace metals

Metals may be transported either via air or water to the Arctic, depending on the specific properties of the metal concerned. A significant contribution to the metal load in lakes originates from weathering of the bedrock in their catchments. This leaching of metals from the soil and bedrock may also be affected by acidification, especially in areas with poorly weathered bed rock. Such areas are to be found in the eastern Canadian Arctic in the northern extension of the Precambrian Shield, including Baffin Island, which has conditions similar to those found in most parts of Scandinavia. Generally, lakes in these areas have soft water which has a high susceptibility to acidification and metals are more biologically active in this type of water than in any other type. In the western Canadian Arctic, however, younger bedrock with limestone and dolomite generally dominates. The production of humic substances is more intense in the Low Arctic than in the Middle and High Arctic, which may influence the distribution and mobility of trace metals in the soil-water systems.

Industrial activities in the form of sulphide ore processing and metal smelters are large point sources in some regions of the Arctic. Furthermore, the long-range airborne transport of metals, originating from industrialized areas of the world, contributes substantially to the metal load in Arctic ecosystems, especially during winter. Spatial and temporal patterns of the metal load are still insufficiently demonstrated, especially in the fresh water ecosystems of the Arctic. However, mercury levels in sediments show an increasing trend indicating a widespread regional process, and mercury levels in some marine mammals have increased by a factor of 2-3 over the last two decades. Cadmium concentrations in birds and mammals from certain areas of the Arctic may be sufficiently high to cause kidney damage (AMAP 1998).

On the various sample matrices collected during Tundra Northwest 1999 both the classic pollutants such as mercury, cadmium and lead, and a variety of “new” elements will be determined. These elements include bismuth, indium, platinum, palladium, antimony, tellurium, thallium and others, and have not yet been measured to any real extent in the environment. In common with more traditional pollutants, some ”new” metals show signs of long-range transport according to preliminary results from Sweden and Norway. Using modern sensitive methods of determination, e.g. ICP-masspectrometry, the number of accurately determined elements can be increased considerably which provides new possibilities for evaluation.

Organic pollutants

Persistent organic pollutants (POPs) constitute a group of ”classic” environmental contaminants such as PCB and DDT, that share the common properties of hydrophobicity, persistence and bio-accumulation. A hydrophobic compound is more readily dissolved in lipids than in water and will therefore be drawn to the fatty tissues of living organisms, a process called bioaccumulation. If hydrophobicity is combined with persistence, i.e. a slow degradation rate, the compound may reach higher concentrations in the tissues of organisms high up in the food chain. In the Arctic, polar bears and traditional hunters are at the very highest level of the food-chain.

The problem with POPs in the Arctic became apparent when it was realized that the Inuit of northern Canada carry higher body burdens of POPs than people in the industrial regions that are source areas (AMAP 1998). This triggered research activities  aimed at understanding the transport mechanisms behind the contamination of the Arctic. The model of long-range transport and global fractionation presented by Wania and Mackay (1996) states that the transport of pollutants via the air will mainly take place via a temperature driven process whereby organic contaminants are volatilized in warm climate zones and deposited in colder areas. In principle, it is the same mechanism by which water condenses on the outer surface of a cold bottle taken out of the refrigerator on a warm summer day. This is called the cold wall effect. The cold climate in the Arctic also means that the degradation of an y organic contaminant will be much slower than in warmer regions. These factors contribute to a situation where contaminants can reach surprisingly high concentrations. The most renowned example is the concentration of α-HCH, an isomer of the insecticide Lindane, which is higher in the Beaufort Sea than in the seas close to the release areas (Wania and Mackay 1996).

On Tundra Northwest 1999 sampling on a broad scale was performed, including different environmental matrices, to understand the transport and circulation of both the classic POPs (PCB, DDT and others) and a variety of ”new” contaminants. These ”new” contaminants are new only in the sense that they have not been routinely measured in the environment previously. These include ”new” POPs such as brominated flame retardants, phenolic compounds and pesticides currently in use. These ”new” contaminants are interesting as they may behave like the classil POPs but they are not yet on the political agenda as problem substances.

Field-work

To understand the large-scale transport of POPs, samples of air and surface seawater were taken. The balance between the concentration in the air and the water will govern much of the global fractionation. Air samplers were operated both on board the ship and at Resolute Bay during the greater part of the expedition.

The fresh water sampling programme consisted of many different matrices: water, suspended particles, sediment cores, different size fractions of zooplankton, and fish (Arctic char). Since all these compartments have been sampled simultaneously, it will provide us with a unique opportunity to study the circulation of the contaminants in the lakes and ponds. The simultaneous measurement of several different limnological parameters and measurements of bacterial activity performed by other groups will further augment the results.

Both lakes with sea-run and landlocked char were sampled and this will allow comparisons between the different ecological life histories of the fish. Due to the limited range of radio communication and helicopter transport most of the lakes sampled were situated relatively close to the coast, and the majority of Arctic char populations were considered to be sea-run. Muscle and liver tissue will be used for determination of organic pollutants and metals, and from large specimens blood samples were also taken at the site to measure phenolic compounds.

Terrestrial samples were taken to map the deposition of POPs and trace metals in the terrestrial environment and to study a short terrestrial food-chain (plants-lemmings). Samples of soil, mosses (generally Hylochomium splendens), lichens, higher plants and lemmings were taken in collaboration with other groups. Higher plants included lemming food plants as part of the food-chain studies, and Cassiope tetragona and Saxifraga oppositifolia for studies of the physical processes involved in the uptake of POPs by plants in the Arctic environment. Due to the complexity of the analyses involved and the risk of contamination, the analyses of both trace metals and organic contaminants will take place after the samples have been received in the borne laboratories. Therefore, no concentration data can be presented as of yet.

Collaboration

Much of the sampling was carried out in collaboration with other groups participating in the expedition. The limnological group (Theme D) co-operated in the sampling of the fresh water environment, and terrestrial samples were collected in collaboration with participants in Theme A and Theme B.