The fate of metals in Arctic surface waters. Method for defining critical levels.

Based upon studies in the industrially developed Arctic region, Russian Kola, here we discuss the fate of metals in high latitude surface water. Mainly, attention is paid to the priority pollutants from copper-nickel smelters. The influence of accompanying processes, such as acidification and eutrophication, on metal behavior is considered. The dramatic situation for fauna of Arctic latitudes is illustrated: (i) during the snow-melt, due to the pulse of ionic metal forms; and (ii) during the long polar winter in lower water layers, due to the involvement of a wide spectrum of metals in the redox-cycle under eutrophication and oxygen deficiency. Here we identify fish pathologies, which are related to the influence of metals. Generalizing the data on metal behavior, an original approach to define the integrated impact dose of metals--a toxicity index--has been developed. It presents a visualization of the integrated toxicity index for surface waters of the Russian Kola (based on the data for a 460-lake survey). As shown, there is a risk of fish diseases, due to both airborne contamination by metals and an indirect leaching by acid runoff over almost 30% of the area of the Russian Kola. For the Arctic region, polar winter stress syndrome will be repeatedly significant. During the polar night, as well as the spring, the vulnerability of the Arctic biota to toxic impact is higher. The accompaniment of water metal-pollution by two or more stressors would occur simultaneously, thereby multiplying the risk that it could develop.