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AGU: Global Biogeochemical Cycles

 

Keywords

  • arsenic
  • atmospheric deposition
  • ice

Index Terms

  • Biogeosciences: Biogeochemical cycles, processes, and modeling
  • Cryosphere: Ice cores
  • Biogeosciences: Contaminant and organic biogeochemistry
  • Biogeosciences: Trace element cycling

Abstract

GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 23, GB3011, 7 PP., 2009
doi:10.1029/2009GB003471

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

Michael Krachler

Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany

Jiancheng Zheng

Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany

Geological Survey of Canada, Ottawa, Ontario, Canada

David Fisher

Geological Survey of Canada, Ottawa, Ontario, Canada

William Shotyk

Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany

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 ∼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 206Pb/207Pb 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.

Received 19 January 2009; accepted 29 May 2009; published 11 August 2009.

Citation: Krachler, M., J. Zheng, D. Fisher, and W. Shotyk (2009), Global atmospheric As and Bi contamination preserved in 3000 year old Arctic ice, Global Biogeochem. Cycles, 23, GB3011, doi:10.1029/2009GB003471.

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