Recent research has shown that the Arctic may be a sink for mercury, however, the fate of this deposited mercury in the environment is not known. The objective of this project was to determine the factors affecting methyl mercury (MeHg) production in Arctic organic soil on the Truelove Lowlands, Devon Island, Canada. In the field we observed a steady decrease in MeHg over time, with MeHg concentration at many sampling locations declining below detection limits. This decrease did not correlate to any chemical or biophysical parameter measured. During the study the Lowlands appeared to be mildly reducing with dissolved Fe(II) being present in the porewater, however, no correlation was observed between MeHg production and the variables measured. The dissolved organic matter concentration of the porewater was quite high, the pH was circumneutral and it would seem that in the absence of more highly reducing conditions that mercury would be unavailable for methylation.<p> It seems likely under field conditions MeHg was much more bioavailable then inorganic mercury. This would lead to a higher rate of demethylation then methylation and a net decrease in MeHg. Little research has been done on demethylation and the effect of environmental conditions on demethylation, especially in arctic environments. However, it is possible that the rate of demethylation was not affected by changes in temperature or any other parameter measured over the course of the field study. <p> Laboratory microcosm studies using saturated soil from the organic horizons demonstrated little potential for unspiked organic soil to produce significant amounts of MeHg. The spiked treatment, however, had an eight fold increase in MeHg concentration and the sterile treatment showed no change in MeHg concentration over 40 days of freeze (-5 0C) and 59 days of thaw (4 oC). <p> Our data suggests that a combination of atmospheric and in-situ processes maintain a cycle of MeHg production (spring) and loss (summer) in arctic soils. It would seem that Arctic wetland soils are not a significant source of MeHg to the Arctic ecosystem and that snowmelt is the dominant source.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-12312007-172450 |
| Date | 02 January 2008 |
| Creators | Oiffer, Lindsay |
| Contributors | Pennock, Dan J., Peak, J. Derek, Hall, Britt, Farrell, Richard E., Siciliano, Steven |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-12312007-172450/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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