Do Rates of Potential Methylmercury Production Differ in Prairie Wetland Sediments Near Coal Fired Power Plants?
Britt Hall, University of Regina, Department of Biology, Regina, SK, Canada, Kyleen Pangracs, University of Regina, Biology, Regina, SK, Canada, Jane Kirk, Environment and Climate Change Canada, Canada Centre for Inland Waters, Burlington, ON, Canada and Derek Muir, University of Guelph, School of Environmental Sciences, Guelph, Canada
Contact First Author: Britt Hall; britt.hall@uregina.ca
English Abstract:
The coal-fired electrical generating power plants in the Estevan area of southeastern Saskatchewan have been identified as some of the largest emitters of atmospheric mercury in Canada. Although power companies have been developing technologies to reduce mercury emissions from flue gas emitted from coal-powered generators, mercury capture technologies are not able to remove all mercury from flue gas. As well, decades of Hg emissions prior to the development of emission controls has likely resulted in large amounts of Hg deposited to Saskatchewan’s lakes and wetlands. The impacts of these mercury emissions on ecosystems, particularly on local aquatic ecosystems with fish and waterfowl present, have not been examined previously. As part of Canada’s Clean Air Regulatory Agenda (CARA) mercury science program we quantified net methylmercury (MeHg) production in cores collected from wetlands surrounding mercury emitting power plants.
Methylation potential rates in sediments were measured in intact cores collected using custom-made core tubes equipped with injection ports. Cores were collected from six wetlands upwind and downwind from the power generation plants. Solutions of porewater and spikes of purified mercury stable were injected through the core tube ports, and the cores are incubated at in situ temperatures for 24 hrs. Cores were sliced at 0.5 cm increments, and slices were analyzed for Me201Hg using an inductively coupled plasma mass spectrometer (ICP-MS) to determine potential rates of mercury methylation. Water and carbon content, porosity, and water chemistry parameters were also measured from cores and surface waters of wetlands. This work is complemented by studies on dated lake sediment cores, providing a history of mercury deposition in the area, and an assessment of mercury levels in aquatic food webs, providing an understanding of MeHg bioaccumulation and biomagnifications in Saskatchewan lakes.
