Grant: Discovery Grants Program - Individual

Mercury contamination poses a significant threat to both natural ecosystems and human health at local, regional and global scales. Man-made mercury emissions have increased dramatically since pre-industrial times and resulted in elevated levels at the local or regional scale. This poses a considerable challenge for regulators tasked with managing mercury in the environment; a detailed understanding of the biogeochemical cycle of mercury is crucial, but not always sufficient. The use of stable isotope techniques, both using isotope enriched mercury as well as measuring stable mercury isotope ratios and mercury isotope fractionation, can aid to trace of mercury though the environment and reveal key transformation processes. Permafrost regions, characterized by permanently frozen ground, have long been considered potential repositories of mercury due to their historical association with cold-trapping processes. In recent years, the accelerated thawing of permafrost has raised concerns about the release of stored mercury into surrounding environments, making it imperative to understand the fate and behavior of this toxic metal in permafrost lake ecosystems. Changing hydrologic connectivity may increase water availability and continued permafrost thaw may lead to surface water with higher concentrations of dissolved organic matter and the production of toxic methylmercury. The proposed research will use various stable isotope techniques and develop new methods for measuring precise isotope ratios not only for total mercury but also to determine compound specific isotope ratios for methylmercury. This new technology will be applied in vulnerable ecosystems such as permafrost soils and lakes to establish the isotopic relationship between inorganic mercury in sediments and water and newly formed methylmercury that is now available for uptake in biota and biomagnification. Field work is conducted in the Canadian Arctic and will be complemented with experiments on Deception Island, Antarctica. Stable isotopes provide unique fingerprints for mercury compounds, enabling accurate tracing of the transformations it undergoes within the aquatic ecosystem. This research proposal seeks to advance our understanding of mercury dynamics in permafrost lakes and polar environments, and its potential implications for regional and global mercury cycling. The integration of modern analytical and stable isotope techniques will offer valuable information about methylmercury formation, export, and fractionation in these ecosystems. The new perspective and our understanding of mercury dynamics in vulnerable environments will help resolve uncertainties relevant to global biogeochemical cycle of mercury. The outcomes of this study will contribute significantly to environmental management and aid in developing effective strategies for mercury pollution prevention and mitigation in permafrost regions.