Global atmospheric As and Bi contamination preserved in 3000 year old arctic ice

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  • Abstract: Despite its growing environmental significance, there are no detailed historical records of atmospheric As deposition for the Northern Hemisphere. Having overcome the severe analytical challenges in measuring As in polar ice, and using an Arctic ice core representing similar to 16 ka of snow accumulation, we present a complete record of atmospheric As deposition for this period which reveals significant contamination beginning 3000 years ago. While Pb enrichments unequivocally increased threefold above natural background levels during Greek/Phoenician, Roman, and Medieval periods, As is elevated by a factor of 5. Previous studies showed that these periods are not only enriched in Pb but also Sb: here we show significant contamination not only by As but also Bi, Cu, and Zn. The Pb isotope data reveal declines in the ratio (206)Pb/(207)Pb which reflects the introduction Pb-bearing aerosols from smelting of lead ores, but the metallurgy of copper ores must also have played a role. Taken together, these findings demonstrate a deeper, broader environmental significance of sulphide ore processing in antiquity, defining the origins of global atmospheric contamination for a suite of related elements and providing a new perspective on the start of the Anthropocene. In addition, the data indicate that by far the greatest As concentrations in the ice core are recorded during the Younger Dryas cold climate event centered around 12 ka B. P., demonstrating the strong link between global climate change and the atmospheric cycling of trace elements.

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    Article (Published)
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    © 2009 American Geophysical Union. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
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    • Krachler, M., Zheng, J, Fisher, D., and Shotyk, W. (2009) Global atmospheric As and Bi contamination preserved in 3000 year old arctic ice. Global Biogeochemical Cycles 23(3), GB3011, doi:10.1029/2009GB003471.