Sources and sinks of contaminants across northern ecosystems

Much of our work has focused on the fluxes and transformations of total mercury (THg) and methylated mercury (MeHg) across northern aquatic ecosystems, from headwaters to coastal marine environments. We use both field surveys and experiments with stable isotope additions to quantify rates of MeHg production and loss in different environments. Analyses are conducted using inductively-coupled plasma mass spectrometry (ICP/MS), cold-vapour atomic fluorescence spectroscopy (CVAFS) and direct mercury analyzers (DMA). 

Recent collaborations have also examined the fluxes of organic contaminants (perfluoroalkyl substances, flame retardants) across northern watersheds (e.g., MacInnis et al. 2019, Environ. Sci. Technol. 53, 10753-10762.).

Example publications:
  • MeHg dynamics across a small High Arctic watershed: Varty et al. 2021, Environ. Sci. Techno. 55, 331-340.
  • Glacial melt impacts on Hg mobilization: St. Pierre et al. 2019, Environ. Sci. Technol. 53, 1175-1185.
  • ​Permafrost thaw impacts on Hg mobilization: St. Pierre, Zolkos and Shakil et al. 2018, Environ. Sci. Technol. 52, 14099-14109
  • Transfer of MeHg from oceans to land: St. Pierre et al. 2015, Environ. Sci. Technol. 49, 5930-5938.
Picture
Conceptual diagram showing total (THg) and methyl mercury (MeHg) fluxes and transformations across a glaciered watershed (Fig. from St. Pierre et al. 2019, Environ. Sci. Technol.).
Picture
Diagram illustrating THg and MeHg by retrogressive thaw slumps in the western Canadian Arctic (from St. Pierre, Zolkos and Shakil et al. 2018, Environ. Sci. Technol.)