High-resolution Monitoring and Modeling of Meltwater Sources and Contaminant Fluxes from the Athabasca Glacier, Canada

Abstract:

As glacier ice melts in the Canadian Rocky Mountains, trace elements, nutrients, and other contaminants, accumulated from millennia of atmospheric deposition, are subject to release in glacier meltwater with potential adverse consequences for downstream water quality. We monitored and modelled meltwater chemistry at a high temporal resolution using grab sampling and sondes at the mouth of proglacial Sunwapta River, which drains the Athabasca Glacier in the Canadian Rocky Mountains. We identified two chemically and temporally distinct sources to melt by principal component analysis: a subglacial component characterized by dissolved carbonate associated elements, and an englacial component which contained potential legacy contaminants predominantly in particulate form and at low concentrations (nitrogen <0.15 mg/L; phosphorus <0.03 mg/L; total mercury <3.2 ng/L; total lead, arsenic, and chromium <2.0 µg/L). We modeled trace element fluxes and yields by correlating grab sampling results with high-frequency physical parameters: conductivity or turbidity. Mercury yield (3.5 g/yr/km²) was comparable to or lower than yields from other glacial meltwater streams globally. Long term discharge data suggests that future contaminant yields will increase until peak water is reached, but at present, glacial meltwater in this iconic Canadian Rocky Mountain alpine setting does not significantly augment nutrient and trace element contaminant budgets.