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TitleArchives of total mercury reconstructed with ice and snow from Greenland and the Canadian High Arctic
AuthorZheng, J
SourceScience of the Total Environment vol. 509-510, 2015 p. 133-144,
Alt SeriesEarth Sciences Sector, Contribution Series 20130457
Mediapaper; on-line; digital
File formatpdf
AreaMount Oxford; Agassiz; Alert; Ellesmere Island; Canada; Greece
Lat/Long WENS-80.0000 -44.0000 83.0000 78.0000
Subjectssurficial geology/geomorphology; ice; ice samples; glaciers; mercury; snow; NEEM
Illustrationslocation maps; plots; tables
Programenvironmental impacts and adaptation in the northern environment, Environmental Geoscience
AbstractThis study reports total Hg concentration and atmospheric flux data from ice cores and snow/ice shallow pits from two Canadian Arctic and one Greenland glaciers, with the aim of reconstructing a high resolution record of THg deposition extending back into the pre-industrial period. An 88-m ice core (653 samples) from the NEEM glacier site in Northwest Greenland was retrieved in August 2010. The bottom sample was dated to 1748, resulting in a 262 year archive. Snow and ice samples (143 samples) were recovered from a 10.3-m pit dug on the Mt. Oxford Icefield, Nunavut, in May 2008, covering 30 years. Another 15.5-m short core drilled on the Agassiz Ice Cap, Nunavut, in April 2009 yielded 191 samples covering 74 years. Net rates of atmospheric THg deposition (FTHg) were calculated based on THg concentrations and snow accumulation rates. Results from NEEM site show that THg and FTHg range from sub-pg g- 1 to 120.6 pg g- 1 (mean = 1.5 pg g- 1, n = 653) and from 0.06 to 1.42 µg m- 2 year- 1 (mean = 0.25 µg m- 2 year- 1, n = 218) respectively, much lower than those found in other natural media such as sediments, peat bogs and wet precipitation. The discrepancy of FTHg found in glaciers from other natural media could mainly be due to the more severe photo-reduction and reemission of deposited oxidized Hg. This study also demonstrates that reproducible THg archives can be reconstructed with glacier ice and snow samples from Greenland and the Canadian High Arctic. The THg archive reconstructed with the short core from NEEM site is so far the longest with the highest resolution in Greenland and the Canadian High Arctic.
Summary(Plain Language Summary, not published)
Ice cores from the Canadian High Arctic and Greenland have been analyzed for contents of total mercury (Hg) in order to understand the trend of atmospheric Hg loading by evaluating the net accumulation of Hg in glacier ice. Archive reconstructed with the Greenland ice core is so far the longest one with the highest resolution for total Hg concentration. It is found with the archives that 1)the Net Hg accumulation rate found in glacier ice follows the pattern of global atmospheric Hg emission; 2)the Net Hg accumulation rate from 2001 to 2010 found in glacier ice is less than half of its counterpart between 1991 and 2000; 3)net Hg accumulation rate on glaciers is much lower than those found in lakes and peatbogs; and 4)archives presented in this publication are comparable and reproducible. Findings in this study will provide information of atmospheric loading estimation of Hg fate and trend.