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TitleAnthropogenic perchlorate increases since 1980 in the Canadian high Arctic
AuthorFurdui, V I; Zheng, JORCID logo; Furdui, A
SourceEnvironmental Science & Technology (ES & T) vol. 52, issue 3, 2017 p. 972-981,
Alt SeriesNatural Resources Canada, Contribution Series 20170311
PublisherAmerican Chemical Society
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNunavut; Yukon
NTS48H/06; 115B/11; 340A/09
AreaCanadian Arctic Archipelago; Agassiz Ice Cap; Devon Ice Cap; Eclipse Icefield; Greenland Ice Sheet; Canada; Greenland; Denmark
Lat/Long WENS -73.1667 -73.0000 80.7500 80.6667
Lat/Long WENS -83.0000 -82.0000 75.4167 75.2500
Lat/Long WENS-139.4667 -139.4667 60.5167 60.5000
Lat/Long WENS -38.4000 38.5000 72.6000 72.5000
Subjectsenvironmental geology; geochemistry; Nature and Environment; Science and Technology; ice sheets; icefields; ice samples; core samples; chlorine geochemistry; atmospheric geochemistry; pollutants; environmental impacts; sulphates; volcanism; depositional history; Ice caps; cumulative effects
Illustrationsplots; time series; location maps; bar graphs
ProgramEnvironmental Geoscience Management
Released2017 12 22
AbstractAn ice core of 15.5 m retrieved from Agassiz Ice Cap (Nunavut, Canada) in April 2009 was analyzed for perchlorate to obtain a temporal trend in the recent decades and to better understand the factors affecting High Arctic deposition. The continuous record dated from 1936 to 2007, covers the periods prior to and during the major atmospheric releases of organic chlorine species that affected the stratospheric ozone levels. Concentrations and yearly fluxes of perchlorate and chloride showed a significant correlation for the 1940-1959 period, suggesting a predominant tropospheric formation by lightning. While concentration of chloride remained unchanged from 1940s until 2009, elevated levels of perchlorate were observed after 1979. A lack of significant increases in either sulfate or chloride between 1980 and 2001 suggests that the effect of volcanic activities on the perchlorate at the study site during this period could be insignificant. Therefore, the elevated perchlorate in the ice could most likely be attributed to anthropogenic activities that influenced perchlorate sources and formation mechanisms after 1979. Our results show that anthropogenic contribution could be responsible for 66% of perchlorate found in the ice. Although with some differences in trends and amounts, deposition rate found in this study is similar to those observed at Devon Island (Nunavut, Canada), Eclipse Icefield (Yukon, Canada) and Summit Station (Greenland). Methyl chloroform, a chlorinated solvent largely used after 1976, peaked in the atmosphere in 1990 and has a much shorter atmospheric life than chlorofluorocarbons (CFCs). This study proposes methyl chloroform (CH3CCl3) as the significant anthropogenic source of perchlorate in the Canadian High Arctic between 1980 and 2000, with HCFC-141b (Cl2FC-CH3), a relatively short-lived CFC probably responsible for a slower decrease in perchlorate deposition after the late 1990s. The presence of aerosols in the stratosphere appears to suppress perchlorate production after 1974. As both methyl chloroform and HCFC-141b had no new significant emissions after 2003, deposition of perchlorate in High Arctic is expected to remain at pre-1980 levels.
Summary(Plain Language Summary, not published)
Chlorine radical (Cl·), which can be liberated from its parent compounds, such as perchlorate, by the action of ultraviolet light, is one of the radicals that can destroyed ozone in the atmosphere. Study of the changing perchlorate trend in the atmospheric environment can evaluate the effectiveness of implementation of the 1987 Montreal Protocol, which targeted the production of ozone-depleting substances. This study aims to reconstruct a temporal series of perchlorate concentration using an ice core of 15.5 meters retrieved from Agassiz Ice Cap (Nunavut, Canada). This study provides a continuous record of perchlorate deposition over a 71-year period between 1936 and 2007. Study found that elevated levels of perchlorate were observed until early 1990s when perchlorate concentration started to decrease quickly. Results suggest that anthropogenic activity influenced perchlorate sources and formation mechanisms after 1979, being responsible for 66% of the perchlorate found in the ice.

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