9:00 am - 10:00 am
849 General Services Building (GSB), University of Alberta, Edmonton Alberta
Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES PhD Final Exam Seminar by Lauren Thompson. This seminar is open to the general public to attend.
PhD with Drs. David Olefeldt and Oliver Sonnentag.
Thesis Topic: Methylmercury production and export across the terrestrial-aquatic continuum in permafrost peatland catchments
Ongoing permafrost thaw in northern peatland catchments may increase the production and downstream delivery ofneurotoxic methylmercury (MeHg) across the terrestrial-aquatic continuum. Peatlands in boreal-Arctic regions have largestocks of mercury (Hg) in frozen soils, accumulated through atmospheric deposition of natural and human-emitted Hgover thousands of years. Permafrost thaw in peatlands may shift environmental conditions to facilitate microbialproduction of MeHg (methylation). However, the degree to which Hg is methylated post-thaw and exported downstreamremains uncertain in northwestern Canada and poses a potential hazard for uptake by aquatic food webs. I initiated threefield studies examining MeHg cycling throughout the peatland-rich Interior Plains of boreal western Canada. First,examining how peatland and permafrost extent influenced MeHg concentrations through a synoptic sampling of lakes andstreams. Second, determining how discharge and land cover controlled the export and concentrations of MeHg in twostream catchments with differing peatland extent. Third, exploring the microbial production of MeHg in thermokarstwetlands compared to intact permafrost peatlands. My findings suggest that permafrost thaw in northern peatlands willenhance Hg methylation across the landscape, although wetland trophic status and groundwater connectivity will controlMeHg production, and catchment hydrological functioning will determine downstream export. This knowledge is importantfor public health planning and land use intervention in the face of climate change, given the high risks of MeHg in aquaticecosystems to northern communities.