Millennial-scale records of atmospheric mercury deposition obtained from ombrotrophic and minerotrophic peatlands in the Swiss Jura Mountains.

Abstract

Peat cores from two bogs were used to reconstruct changes in net atmospheric mercury deposition in Switzerland for the past 2-3 millennia. The two records were compared to assess the reliability of peat cores as archives of atmospheric mercury deposition. Net mercury accumulation rates and Hg(ex), an indicator of significant anthropogenic mercury contamination, were calculated for both cores. Both records showed stable background values (0.5-1.9 and 1.0-3.0 microg of Hg m(-2) yr(-1)). In both profiles, mercury accumulation rates began to increase during the 12th century, and Hg(ex) appeared during the 14th century. The late 19th and early 20th centuries have been studied in detail. The profiles match well with the history of local and global mercury emissions. The magnitude of increase from the pre-anthropogenic to anthropogenic period was also very similar in both records. Although the two sites are botanically very similar and lie only 3.5 km apart, accumulation rates at TGE were generally higher than those at EGR. This indicates that, although such records can be used to determine the chronologies of and relative changes in rates of atmospheric mercury deposition, differences in rates of mercury accumulation rates between sites do not necessarily indicate differences in deposition rates of mercury from the atmosphere.