METAL CONTAMINATION OF THE NATURAL ENVIRONMENT IN NORWAY FROM LONG RANGE ATMOSPHERIC TRANSPORT
Long range atmospheric transport is the most important source of contamination to the natural environment in Norway with many heavy metals. Investigations based on aerosol studies, bulk deposition measurements and moss analysis show that airborne transport from other parts of Europe is the major mode for supply of vanadium, zinc, arsenic, selenium, molybdenum, cadmium, tin, antimony, tellurium, thallium, lead, and bismuth, whereas metals such as chromium, nickel, and copper are mainly derived from point sources within Norway and in northwestern Russia close to the Norwegian border. Elements associated with long range transport show substantial enrichment in the humus horizon of natural soils in southern Norway, sometimes to levels suspected to cause effects on soil microbial processes. E.g. lead concentration values of 150–200 ppm are observed in the most contaminated areas in the south as compared to about 5 ppm in the far north. Elements such as lead and cadmium also show enrichment in some terrestrial food chains. These elements also show considerably elevated levels over background concentrations in the water and sediment of small lakes in the southern part of the country. Retrospective studies based on ombrogenous peat cores indicate that long range transport has been a significant source of heavy metal contamination in southern Norway for the last couple of centuries. The deposition of most heavy metals in Norway has been considerably reduced over the last 20 yr, with the exception of contributions in the north from Russian smelters.