SNOW FLUXES AND MELT DYNAMICS OF TRACE ELEMENTS AT ELIOT GLACIER: SOUTH CASCADES, OREGON

Potentially toxic metal inputs onto glacier snow and their subsequent introductions into glacier melt streams need to be critically evaluated. Although much work has investigated metal fluxes to polar regions, few studies have examined trace metal melt dynamics. This understanding is especially important for temperate glaciers, where atmospherically introduced metals may rapidly enter our water supplies. The incorporation of health-harmful metals, such as Pb and V into glacier melt systems can be linked to geologic setting, proximity to urban centers, and each glacier's unique hydrology. Glaciers in the Oregon Cascades melt three-fourths of the year with water routed on, through, and underneath the glacier. It is unknown how metals are gained and lost en route. This study details snow and bulk meltwater chemistry from Eliot Glacier, Mount Hood, the primary water source to local farms. We have determined concentrations of As, Cu, Cd, V, Sr and major ions in fresh and ablation snow and in bulk meltwater. Ionic ratios of possible end-member sources may be used to distinguish metal contributers to both the snow and bulk meltwater. Cu:Sr ratios imply that 70% of the Cu found in ablation snow is rock derived with 25- 30% from anthropogenic sources. The Cu:S and the Pb:S ratio of Eliot Glacier snow suggest less than 5% may originate from volcanic sources. V was the only metal studied that was primarily added to snow via anthropogenic activities, mainly fossil fuel combustion. High bulk melt water abundances of F- (2.2 µM), Cl- (112 µM) suggest some hydrothermal contributions to bulk glacier melt (< 10%). V, Sr, As, are enriched in bulk glacier melt with respect to snow (EF=61, 48, 3), whereas Pb and Cd are depleted (EF= 0.03, 0.5). We interpret bulk meltwater enrichments to indicate chemical weathering additions and depletions to indicate absorption onto particles.