CGRG Bibliography of Canadian Geomorphology
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Author : Dickson, A.; Levy, S.; and Siciliano, S.
Date : 2005.
Title : Mercury partitioning in High Arctic groundwater, Truelove Lowland, Devon Island, NU.
Publication : 35th Annual International Arctic Workshop. March 9-12, 2005. Timms Centre for the Arts, University of Alberta, Edmonton, Alberta, Canada.
Issue :
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Abstract
Mercury levels continue to increase in the Canadian Arctic. Our understanding of how mercury is transported to polar regions has advanced. However, very little is known about the fate of mercury after it is deposited on the Arctic landscape. Mercury partitioning between the aqueous and particulate phase in groundwater influences the fate and transport of mercury in ecosystems. We hypothesized that adorption to sulfate reducing bacterial biomass and/or production of biogenic sulfides would cause in an increase in particulate-bound mercury in High Arctic groundwater. We evaluated this hypothesis through a combination of field observations as well as in situ and ex situ manipulated microcosms. Analysis of pH, redox potential, electrical conductivity, temperature, total mercury and dissolved mercury was done in the field. Major cations, anions, iron (II), iron (III), total organic carbon and dissolved organic carbon were analyzed in the lab. Microcosms were subjected to five different treatments: anaerobic control, anaerobic gamma-irradiated, anaerobic sulfate reducing bacteria-inhibited (3mM sodium molybdate), aerobic control and aerobic gamma-irradiated. The anaerobic microcosms were redox-poised with titanium(III)nitrilotriacetate. At Truelove Lowland a steady and significant increase in the mean particulate mercury (as a percent of total mercury) was observed from the first sampling (67% „b 3.4) to the fourth sampling (86% „b 3.2). A marked decrease in mean particulate mercury was observed on the fifth and final sampling date (66% „b 5.0). Total mercury did not differ between microcosm treatments (1.7 ng L-1). There was significantly more particulate mercury in the anaerobic sulfate reducing bacteria-inhibited treatment (82% „b 2.2) than the anaerobic control (75% „b 2.3) and anaerobic killed treatment (77% „b 1.5). Microbial activity in High Arctic groundwater alters the partitioning of mercury between the aqueous and particulate phases. This study will be concluded with: 1) a laboratory experiment designed to further elucidate the mechanism by which particulate mercury is increased and 2) a spectroscopic examination of the particulate material present in the groundwater and microcosms.
Bibliography of Canadian Geomorphology