Mercury deposition and accumulation in
Canadian Rocky Mountain lakes

Objectives & Methodology

The overall objectives of this research are to determine the extent of Hg contamination in the Rocky Mountains and to study Hg²⁺ deposition and MeHg bioaccumulation in mountain lakes of differing elevation. Erin hypothesizes that

• Hg²⁺ deposition will increase with elevation because of increased precipitation volume, which will lead to a larger spring pulse of Hg²⁺ in high elevation lakes than in lower lakes
• Alpine lake biota will contain greater concentrations of Hg than organisms from lower mountain lakes because of increased Hg exposure due to high deposition and increased organism longevity, which influences bioaccumulation.

The methodology for this study included a snow Hg survey, and sampling for Hg in water, zooplankton, and benthic invertebrates during the fall of 2000 and the spring of 2001. Small and large fishes were collected from a subset of the lakes in 2001. Preliminary results indicate that fish in some lakes in Canadian Rocky Mountain Parks contain Hg in excess of the 0.5 ug/g consumption guideline. Lake surface water data indicates that Hg concentrations do not increase with elevation. This could be due to photochemical reactions that cause the revolatilization of Hg from water.

Moab Lake Fire 2000 Jasper National Park (Parks Canada)	Study Lake: Lake O'Hara, Yoho National Park

Forest Fire and Hg

While completing initial sampling of the study lakes, 72% of the catchment of Moab Lake burned in a forest fire. This provided an opportunity to quantify some of the effects of fire on water chemistry and Hg dynamics in aquatic systems. Moab Lake and 4 creeks (2 creeks in burned catchments and 2 in unburned catchments) were sampled during the ice-free period for 2 years. The results should reveal important information about the impact of forest fires on mercury cycles.Preliminary results reveal elevated concentrations of mercury in water and some organisms post-fire.

Acknowlegements

Invaluable field and lab assistance was provided by Brian Parker, Michelle Bowman, Cathy Lemmon, Kathy Vladicka, Laurie Cheperdak, Mark Van Dorn, and Parks Canada wardens. Many thanks to Dr. David Kelly, Jane Kirk, Megan Pouchniak, and Susitha Wanigaratne of the University of Alberta Low-Level Mercury Analytical Laboratory. This research was funded by the National Science and Engineering Research Council (NSERC), Alberta Science and Research Authority (ASRA), Circumpolar/Boreal Alberta Research (C/BAR), Challenge Grants in Biodiversity, Parks Canada, and Science Horizons.

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