Ecosystem Sensitivity to Atmospheric Mercury Pollution in Canada
Mercury (Hg) pollution from diffuse atmospheric sources is an ongoing concern in many regions of Canada, but aquatic ecosystems vary widely in their sensitivity to Hg deposition. That is, foodweb bioaccumulation and biomagnification of ambient Hg can vary substantially among lakes across Canada’s dominant ecosystems (ecozones) and sub-regions (ecoregions and ecodistricts). As a physical environmental geographer, I am particularly interested in understanding top-down climatic and physiographic drivers of these inter-lake and inter-regional differences in aquatic ecosystem Hg sensitivity.
In this talk, I will present results from several recent collaborative research projects focused on understanding first-order drivers of aquatic ecosystem Hg sensitivity in Canada. I will begin with an overview of the complex but fascinating myriad of factors that influence Hg pathways in northern watersheds and lakes. Following this I will discuss a new conceptual and statistical modeling framework for pan-Canadian predictive mapping of aquatic ecosystem Hg sensitivity, using a large database of over 6500 fish Hg samples from across the country. Finally, I will present a synthesis of recent field observations from four climatically and physiographically distinct research sites spanning 30o of latitude, from southwestern QC to Resolute Bay, NU. Results from both model- and field-based studies point towards strong climatic influences on mobility and accumulation of Hg in lakes and watersheds across Canada.
Murray Richardson received his PhD in the department of Geography at the University of Toronto in 2010. Dr. Richardson is an assistant professor in the department of Geography and Environmental Studies at Carleton University, Ottawa. He conducts research in geomatics, physical hydrology and the biogeosciences, specializing in quantitative analysis of landscape and ecosystem structure and representation within environmental models. Current research projects include field research and remote sensing activities in Ontario, Quebec and Nunavut, to characterize and model trace metal cycling and pathways in northern watersheds and lakes.