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 c ontribution of lead and its portion from long-range transport of air pollut ion 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 pres ented in the paper show that phase-out of lead additives to gasoline in Nor thern Europe has not phased out the Pb contamination of the environment. Th e 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 t he period when the combustion of gasoline, the major source of Pb contamina tion has been decreasing. Wood combustion is one of these sources in Norway . Lower impact of long-range transport of air pollutants emitted from sourc es in Eastern and Central Europe and transported with air masses to Scandin avia, during the recent 5 years, can also be traced utilizing isotopic rati os of lead. The application of tree-rings as environmental archives contrib uted significantly to elucidating the historical Pb pollution. (C) 1999 Els evier Science Ltd. All rights reserved.