The Pb pollution fingerprint at Lochnagar: The historical record and current status of Pb isotopes

Ratios of Pb-206/Pb-207 in a Lochnagar sediment core slowly decline from c. 1.32 at 140 cm to c. 1.23 at 9 cm, and then rapidly decline to c. 1.15 at the surface. Ninety percent of the Pb in the surface sediments can be attributed to anthropogenic sources. The Pb-206/Pb-207 ratio data imply that catchment peat surface contains a higher fraction of anthropogenic Pb than the sediment surface. The Pb-206/Pb-207 ratios in the surface of the sediment core are consistent with ratios in trapped sediments collected annually between 1998 and 2003. However, there is no significant decline in these recent samples suggesting that the reduction in atmospheric Pb emissions has not yet been recorded by the sediments due to Pb inputs from the catchment. As catchment peats store about 840 kg previously deposited anthropogenic Pb since 1860, it is likely that catchment inputs will continue to affect future Pb-206/Pb-207 ratios. (c) 2006 Elsevier Ltd. All rights reserved.