A Factor and Trends Analysis of Multidecadal Lower Tropospheric Observations of Arctic Aerosol Composition, Black Carbon, Ozone, and Mercury at Alert, Canada

Observations from 1980 to 2013 of 20 aerosol constituents, ozone and mercury at Alert, Canada (82.50°N, 62.35°W), were analyzed for trends and dominant factors of the Arctic haze during winter and spring. Trends reflect changing emissions in Eurasia, the main source region for surface pollution in t...

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Veröffentlicht in:Journal of geophysical research. Atmospheres 2019-12, Vol.124 (24), p.14133-14161
Hauptverfasser: Sharma, S., Barrie, L.A., Magnusson, E., Brattström, G., Leaitch, W.R., Steffen, A., Landsberger, S.
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Sprache:eng
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Zusammenfassung:Observations from 1980 to 2013 of 20 aerosol constituents, ozone and mercury at Alert, Canada (82.50°N, 62.35°W), were analyzed for trends and dominant factors of the Arctic haze during winter and spring. Trends reflect changing emissions in Eurasia, the main source region for surface pollution in the high Arctic. SO42−, H+, NH4+, K+, Cu, Ni, Pb, Zn, nonsoil V, nonsoil Mn, and equivalent black carbon decreased between 23% and 80% as emissions declined rapidly in northern Eurasia during the early 1990s. NO3− increased by 20% as aerosol acidity declined. Metals were linked to emissions from smelting and fossil fuel combustion. In winter, ozone increased by 5% over 23 years, consistent with other observations and global modeling. Twelve PMF factors emerged for the dark period (November to February) and 13 for the light period (March to May). Eleven PMF factors are common to both dark and light, a twelfth factor was associated with sulfate in the dark and nitrate in the light, and the thirteenth (light period) was related to ozone and gaseous mercury depletion near Alert. IODINE and NITRATE factors, important for Arctic chemistry, changed with sunlight. In the light, 50% of all NO3− was on the NITRATE factor, while in the dark, most was associated with MODIFIED SEA SALT and equivalent black carbon. In the dark (light), 90% (28%) of iodine were found on the factor IODINE and 58% associated with SEA‐SALT and MODIFIED SEA‐SALT. These results help in understanding the role of atmospheric chemistry in weather and climate processes. Key Points Over 34 years, aerosol pollution constituents at Alert Canada decreased between 28% and 80% including black carbon decline at 52%; nitrate, sodium, and chloride concentrations increased between 19% and 43%, whereas ozone increased by 5% A positive matrix factor analysis contrasting dark and sunlit periods revealed information on sources and aerosol chemistry processes Twelve (dark period) to 13 (sunlit period) aerosol and gas factors yielded information on sources and/or physical and chemical processes that allowed for better interpretation of observed trends
ISSN:2169-897X
2169-8996
2169-8996
DOI:10.1029/2019JD030844