NIWR at WERC

Tracking the fate of mercury in downstream freshwater habitats affected by rapid deglaciation in Alaska using stable isotopes

  • Project Student PI: Drew Porter
  • Project Faculty PI/Co-PI: Benjamin Barst & Matthew Wooller
  • Keywords: mercury, stable isotopes, deglaciation

Abstract

Alaska’s hydrology and related ecosystems are undergoing rapid alterations due to climate change. Deglaciation promoted by climate warming is reshaping streamflow and watershed coverage throughout coastal Alaska, these changes could potentially influence the mobilization of mercury in watersheds.

We propose building upon ongoing efforts to assess the fate of mercury in two watersheds (Kachemak Bay and Lynn Canal) in Alaska. We propose conducting a suite of analyses (compound specific stable isotopes of amino acids, bulk stable isotopes, and total mercury) of mussels collected from these watersheds representing distinct levels of glacial influence. These mussels were previously collected as part of the ongoing research efforts of the EPSCoR Fire and Ice Coastal Margins team and are currently available for this proposed research project.

Here we analyze total mercury in conjunction with isotopic analyses (bulk and compound specific stable carbon and nitrogen) to better resolve the pathway of mercury transfer in these watersheds. All analyses will take place at UAF: total mercury will be analyzed (by direct mercury analyzer) in the Marine Ecotoxicology and Trophic Assessment Laboratory and the bulk, and compound specific, stable isotope analyses will be performed in the Alaska Stable Isotope Facility (using CF-IRMS and GCIRMS). The coupling of these analyses will allow us to determine sources of primary production the mussels without requiring additional sampling effort. The results of these analyses will reveal sources of nearshore mercury contamination in the study watersheds as well as how deglaciation is influencing mercury export.

We propose making all our data available to the EPSCoR Fire and Ice team and will publish the findings in a peer reviewed journal article. The results of this study can also be more widely applicable for future researchers interested in the hydrologic export of contaminants from watersheds and potential implications of deglaciation brought on by climate warming.