Two thousand years of atmospheric arsenic, antimony, and lead deposition recorded in an ombrotrophic peat bog profile, Jura Mountains, Switzerland

A peat core from a Swiss bog reveals significant enrichments of As, Sb, and Pb extending back to Roman times, indicating that the anthropogenic fluxes of these metals have exceeded the natural fluxes for more than 2000 years. The isotopic composition of Pb provides no evidence of vertical downward Pb migration, suggesting that the bog has faithfully preserved the historical record of atmospheric Pb deposition. Age dating using Pb (verified independently using pollen markers) provides the chronology of changing metal concentrations during the past 150 years. Present day enrichment factors (relative to the metal/Sc ratios of typical crustal rocks) are of the order of 20 times (As), 70 (Sb), and 130 (Pb). Given the potential toxicity of As and Sb, these new findings suggest that the environmental significance of these, and perhaps other less common trace elements, deserve more attention.