Abstract by Brian Packer
Mercury and Dissolved Organic Matter Dynamics During Snowmelt in the Upper Provo River, Utah, USA
Mercury (Hg) is deposited onto mountain watersheds through atmospheric deposition and mobilized during snowmelt runoff. This study focused on Hg and DOM dynamics in the snowmelt-dominated upper Provo River watershed, northern Utah, USA. We sampled Hg, dissolved organic carbon (DOC) concentrations, and DOM fluorescence over four years from 2014-2017 to investigate Hg transport mechanisms. During the snowmelt season (April-June), Hg concentrations typically increased from ~1 to ~8 ng/L showing a positive correlation with DOC. The filtered Hg fraction was dominant in the river, averaging ~75% of total concentrations, suggesting that DOC is more important for transport than suspended particulate matter. Ephemeral channels had the highest Hg (>10 ng/L) and DOC (>10 mg/L) concentrations, suggesting a soil water source of Hg and organic matter. Fluorescence spectroscopy results showed changes in DOM type and quality during the snowmelt season. Changes in DOM characteristics during snowmelt improve the understanding of Hg dynamics with organic matter and elucidate transport pathways from the soil, ephemeral channels and groundwater to the Provo River.