Long-term records of atmospheric deposition of mercury in peat cores from Arctic, and comparison with bogs
Because of the strong tendency of mercury (Hg) to bioaccumulate in the food chain, one of the greatest challenges faced by environmental mercury research in the Arctic is to quantify the relative contribution of anthropogenic sources of mercury to the contamination of this environment, as anthropoge...
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| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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HAL CCSD
2004
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| Subjects: | |
| Online Access: | https://theses.hal.science/tel-00009797 https://theses.hal.science/tel-00009797/document https://theses.hal.science/tel-00009797/file/tel-00009797.pdf |
| Summary: | Because of the strong tendency of mercury (Hg) to bioaccumulate in the food chain, one of the greatest challenges faced by environmental mercury research in the Arctic is to quantify the relative contribution of anthropogenic sources of mercury to the contamination of this environment, as anthropogenically elevated mercury deposition over the past 150 years in Arctic ecosystems is potentially a serious environmental problem. To determine the magnitude of this concern, it is necessary to quantify the natural “background” of atmospheric mercury deposition and its variation over a millennial-scale period of time. A second problem is to understand the role which is played by the unique climate of the Arctic on the deposition of atmospheric mercury. Total mercury concentrations were determined in peat cores from the High Arctic of Canada, the Faroe Islands and southern Ontario. The cores were dated using 210Pb and 14C. The mercury concentrations were used to calculate rates of atmospheric mercury accumulation in the peat in order to quantify rates of atmospheric deposition of mercury in the Arctic. In addition, rates of atmospheric mercury accumulation in the Arctic were compared with peat cores from the temperate zone of North America (southern Ontario). Mercury concentration measurements and age dating of two peat hummocks from Bathurst Island, Nunavut indicate rather constant natural “background” mercury flux of ca. 1 µg m-2 per year from 5900 to 800 calibrated year BP. The values are well within the range of the Hg fluxes reported from other Arctic locations (Greenland and the Faroe Islands) but also by peat cores from southern Canada (Ontario) which provide a record of atmospheric Hg accumulation extending back to eight thousand years. Thus, pre-anthropogenic Hg fluxes in the Arctic were not significantly different from atmospheric Hg fluxes in the temperate zone. In pre-industrial times, therefore, the High Arctic was not more important as a sink for global atmospheric mercury than the temperate zone. ... |
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