Sphagnum mosses as archives of recent and past atmospheric lead depositionin Switzerland

Sphagnum mosses received from a herbarium and collected recently from a pea r bog surface, were used to assess the isotopic character of past and recen t atmospheric Pb deposition in;Switzerland and to constrain possible Pb sou rces. Lead removed from the moss surface was isotopically similar to that m easured in the corresponding solid plant, suggesting that neither preservat ive actions for the herbarium samples nor dust had affected the isotopic co mposition of the samples. The addition of HCl to aqueous extracts to remove surface particles from the plants released more Pb compared to H2O alone. The changes in isotope ratios between Sphagnum collected during the past c. 130 yr were significantly greater than the small fluctuations between and among species collected at any one time. Three isotope ratio plots and emis sion inventories indicated that the most likely source of atmospheric Pb wa s coal-burning at the turn of the century, fly ash from waste incineration until approximately 1950, and gasoline combustion after that. The pollution record derived from the Sphagnum plants is in good agreement with other ar chives from Switzerland (peat, sediment, ice) and with other herbarium reco rds in Europe. (C) 1999 Elsevier Science Ltd. All rights reserved.