Legacy contaminant release from the cryosphere to downstream systems

• Author / Creator

  Staniszewska, Katarzyna

• Anthropogenic climate warming is degrading the cryosphere. Retreating alpine glaciers and thawing permafrost pose the risk of releasing previously sequestered legacy contaminants to downstream environments, with potential negative consequences for downstream aquatic ecosystems. In this thesis I present the results of high temporal resolution hydrochemistry monitoring and modeling from proglacial Sunwapta River, which is fed by glacial melt in the Canadian Rocky Mountains, and Old Crow River in arctic Yukon, which is underlain by continuous permafrost. Relations between the hydrochemistry dataset and high-resolution monitoring data (e.g. discharge, conductivity, turbidity) were used to model daily contaminant concentrations and estimate annual fluxes and yields. Nutrient and trace element contaminant concentrations, fluxes, and yields were low, dominated by particulate phases, and positively related to discharge in both systems. In the Sunwapta River, two chemically and temporally distinct sources to melt were distinguished: a subglacial component characterized by dissolved elements associated with carbonate, and an englacial component which contained potential legacy contaminants predominantly in particulate form and at low concentrations. In the Old Crow River, contaminant concentrations peaked during the high-discharge spring freshet. Thaw slumps and thermokarst-connected tributaries to the Old Crow River did not significantly raise contaminant concentrations during the summer period of peak ground thaw, which was associated with very low contaminant fluxes. The annual yield of mercury was low (3.2 g/km2/yr at Sunwapta River; 0.8 g/km2/yr at Old Crow River) and comparable to natural temperate streams. Positive trends in historic water yield at both study sites suggest contaminant fluxes have increased over the past > 40 years. Collectively, the results suggest that other glaciers in the Canadian Rocky Mountains, and degrading permafrost in moderately sized arctic watersheds, release low levels of particle-bound contaminants to their downstream environments that predominantly augment sedimentary contaminant stocks.

• Subjects / Keywords

  • river
  • hydrochemistry
  • anthropogenic
  • contaminant
  • mercury
  • flux
  • nutrient
  • thaw slump
  • climate
  • thermokarst
  • permafrost
  • glacier
  • hydrology
  • sunwapta
  • cryosphere
  • glacial
  • old crow
  • legacy
  • athabasca glacier

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-9xs8-g864

• License

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