Reconstructing regional-scale lead contamination of the atmosphere (1850-1980) in the United Kingdom and Ireland using lake sediments

A data set of 49 sediment cores from 41 lakes in the United Kingdom and Ireland was used to investigate how the variability of anthropogenic Pb concentration and accumulation rate affects using lake sediments to reconstruct Pb contamination of the atmosphere at the regional scale. The anthropogenic Pb concentration, when averaged over six to eleven lakes in subregions, was sufficient to isolate the trend in Pb contamination of the atmosphere since 1850 from lake-specific influences. While the anthropogenic Pb accumulation rate varied considerably within subregions, as a result mainly of variable sediment focusing, the results showed that the maximum focusing factor is typically 1.5 to 3 and rarely above 4. Careful application of this finding may allow the history and geographical variation of Pb deposition from the atmosphere at the regional and global scales to be described using lake sediments. A model that relates anthropogenic Pb concentration in lake sediment to Pb flux from the atmosphere was developed and used to reconstruct Pb flux from the atmosphere in three subregions; the reconstructed flux varies from 2.7+/-0.9 to 18.9+/-5.2 mgPb m(-2) yr(-1) across the subregions in 1860-1870 to 7.4+/-2.1 to 34.5+/-6.0 mgPb m(-2) yr(-1) in 1940-1950.