期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 117, 期 8, 页码 3967-3973出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1910485117
关键词
ice cores; trace metals; paleoenvironment; monsoon; North Atlantic Oscillation
资金
- NSF Atmospheric Chemistry Program [1149239]
- NSF-Earth System History Program
- Ohio State University
- Ohio State Committee of Science and Technology
- National Natural Science Foundation of China
- NSF-Major Research Instrumentation Award [0820779]
- Climate Water Carbon Program of The Ohio State University
- Div Atmospheric & Geospace Sciences
- Directorate For Geosciences [1149239] Funding Source: National Science Foundation
- Office of Polar Programs (OPP)
- Directorate For Geosciences [0820779] Funding Source: National Science Foundation
Because few ice core records from the Himalayas exist, understanding of the onset and timing of the human impact on the atmosphere of the roof of the world remains poorly constrained. We report a continuous 500-y trace metal ice core record from the Dasuopu glacier (7,200 m, central Himalayas), the highest drilling site on Earth. We show that an early contamination from toxic trace metals, particularly Cd, Cr, Mo, Ni, SB and Zn, emerged at high elevation in the Himalayas at the onset of the European Industrial Revolution (similar to 1780 AD). This was amplified by the intensification of the snow accumulation (+50% at Dasuopu) likely linked to the meridional displacement of the winter westerlies from 1810 until 1880 AD. During this period, the flux and crustal enrichment factors of the toxic trace metals were augmented by factors of 2 to 4 and 2 to 6, respectively. We suggest this contamination was the consequence of the long-range transport and wet deposition of fly ash from the combustion of coal (likely from Western Europe where it was almost entirely produced and used during the 19th century) with a possible contribution from the synchronous increase in biomass burning emissions from deforestation in the Northern Hemisphere. The snow accumulation decreased and dry winters were reestablished in Dasuopu after 1880 AD when lower than expected toxic metal levels were recorded. This indicates that contamination on the top of the Himalayas depended primarily on multidecadal changes in atmospheric circulation and secondarily on variations in emission sources during the last 200 y.
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