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Dryad

Latitudinal gradients of snow contamination in the Rocky Mountains associated with anthropogenic pollutant sources

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Dec 16, 2024 version files 30.03 KB

Abstract

Seasonal snow is an important source of drinking water, recreation, and agriculture in the Rocky Mountain region. Monitoring snow-water quality is important to assess potential impacts to downstream water resources, impacts to the albedo and energy balance of the snowpack, and assessing sources of natural and anthropogenic aerosols and gases.  Here, a suite of metals were measured from seasonal snowpack from water year (WY) 2018. Calcium, lanthanum, and cerium concentrations support the importance of mineral dust to the southern Rocky Mountains. Mercury (Hg), zinc (Zn), and cadmium (Cd) concentrations show a similar spatial pattern to mineral dust, whereas antimony (Sb) concentrations are highest in the northern Rocky Mountains. Using enrichment factors to adjust for the contributions from mineral dust, it was demonstrated the pollution fraction of Hg, Zn, Sb and Cd was greater in the northern Rocky Mountains. These observations were compared to spatial trends of the pollution fraction of Hg from WY2009 to WY2018, regional monitoring networks, and back trajectory analyses. The agreement between these datasets revealed temporally consistent pollution sources and transport processes to the northern Rocky Mountains snowpack. Potential sources include current and historical mining and smelting in the region. Strategies to limit the emissions of these metals to the Northern Rockies would need to focus on remediation of contaminated sites and continued monitoring and mitigation of active mining and smelting