The origin of atmospheric lead in Oslo, Norway, studied with the use of isotopic ratios

Application of the lead isotope method to differentiate between the local contribution of lead and its portion from long-range transport of air pollution from sources a few thousand kilometers away to the lead pollution level measured in the Oslo area in Norway is discussed. The Pb-206/Pb-204 ratio is of particular interest in this respect. The results of measurements presented in the paper show that phase-out of lead additives to gasoline in Northern Europe has not phased out the Pb contamination of the environment. The lead isotope method proved very useful to present a contribution of small local sources to the Pb contamination of the air in the Oslo area during the period when the combustion of gasoline, the major source of Pb contamination has been decreasing. Wood combustion is one of these sources in Norway. Lower impact of long-range transport of air pollutants emitted from sources in Eastern and Central Europe and transported with air masses to Scandinavia, during the recent 5 years, can also be traced utilizing isotopic ratios of lead. The application of tree-rings as environmental archives contributed significantly to elucidating the historical Pb pollution. (C) 1999 Elsevier Science Ltd. All rights reserved.