Long- range transport of pollutants, especially of POPs, radionuclides and certain metals, is currently the most important pollutant-related pressures on the Barents Sea. This is also the main source for accumulation of POPs in arctic top predators and the main reason that environmental goals are not met (AMAP 2009, see chapter Current and expected state of the ecosystem - Some aspects of possible long-term future changes in the ecosystem). In order to maintain the Barents Sea as a clean and rich sea in the future, knowledge of transport routes, changes in transport routes due to e.g climatic changes and regulations of use of new chemicals is important.
Regulation of hazardous substances
There has over the last ten years been an increased international policy effort to reduce the use and emission of a number of POPs and many of the hazardous substances has been banned. As a result, levels of many of such legacy POPs are declining. However, the growing knowledge about POPs and how they behave in the environment have raised concerns about several groups of chemichal that have similar characteristics as legacy POPs and that are not currently regulated by international agreements. In the Arctic, there are evidence that some of these man-made chemicals, are transported to the area and that the levels are increasing in the environment (AMAP 2009). Monitoring results from the Barents Sea have also confirmed the precence of some of these groups of chemicals in the marine biota and sediments. Measured levels of these groups of chemicals are however, still much lower than levels of legacy POPs and below levels that are related to effects. On a longer term some of these substances may be a problem if not regulated . However, these groups of chemicals have not been studied as thoroughly as the legacy POPs with respect to their environmental fate and distribution in the Arctic areas (AMAP 2009). There are therefore a urgent need for increased knowledge about effects (including combined effects of pollutants), how they accumulate and levels and trends in the environment. This is important for the ongoing considerations of new chemicals for inclusion under existing national, regional and global agreements (The Stockholm Convention and the POPs protocol of UN ECE LRTAP Convention) to regulate the use and emissions of POPs.
Effects of climate change
Transport and redistribution pathways of hazardous substances to and within the Arctic and the Barents Sea is expected to be influenced by climate change processes. Reactivity, transformation, adsorption and desorption processes as well as accumulation of hazardous substances, are temperature dependent processes. It is expected that when atmospheric and ocean currents, sea and land ice changes as a result of climatic changes, also the extent and composition of potential intermediate storage media for pollutants (particle composition in air, snow and ice as well as sediment and soils) such as forests (vegetation profile and species composition etc.) in sub-Arctic areas (Russian and Norwegian sub-Arctic regions) will change. Therefore, changes in global climate and the associated environmental changes in the Arctic are expected to have significant consequences for contaminant pathways both with respect to transported chemicals, contaminant patterns and transformation processes (Macdonald et al. 2005). There are already some indications that trend with a steadily decreasing input from the atmosphere of organic pollutants during the last decade may be broken and the increased concentrations of PAH measured at Zeppelin in 2007 may be the first sign of a climate induced change in long range transport of air-borne pollutants (see also chapter Current and expected state of the ecosystem - Human activities /impact - Pollution; Current and expected state of the ecosystem - Conclusions about state of the ecosystem - Effects of climate change and Current and expected state of the ecosystem - Some aspects of possible long-term future changes in the ecosystem - Effects of climate change on pollution.)
During the past years, numerous research activities have been initiated in order to explain the consequences of global change processes on occurrence, transport and fate of anthropogenic pollutants in remote Arctic regions. However, the “state-of-the-science” is still incomplete and need comprehensive assessment also in the future. Today, it becomes more and more clear that a thorough science based understanding of temporal as well as spatial distribution patterns, including comprehensive source elucidation for selected pollutants, is mandatory for a validated assessment of all factors influencing chemical transport processes (air and ocean- and ice-borne transport) as well as regional pathways leading to the accumulation of selected persistent chemicals in the Arctic ecosystem.