Abstract
Glaciers are a reservoir of mercury (Hg) and other trace elements that have accumulated in the ice during the industrial era. As glaciers continue to melt at an alarming rate, these potentially toxic metals are released to the environment. In order to evaluate the impact of glacier melt on water quality in high elevation catchments in Grand Teton National Park, we sampled transects along the Teton and Middle Teton glaciers and proglacial streams during early-July and mid-August 2013. The glaciers were snow-covered during July, and thus water samples were primarily melt of snowpack from the previous winter. The glacier ice was exposed during August, and thus samples likely represented true glacier melt. These contrasting sample sets allowed for a determination of the impact of snowmelt versus glacier melt on water chemistry. Ten samples were collected during July and August along the Glacier Gulch transect: four of surface drainage on the Middle Teton glacier, three near the terminal moraine, and three downstream of the glacier. Thirteen samples were collected during July and August along the Garnet Canyon transect: one at the Lower Saddle of the Grand Teton, four of surface drainage on the Middle Teton glacier, two near the terminal moraine, two at the moraine of Teepe Glacier, and four samples downstream of the glaciers. All water samples were analyzed for total Hg, a suite of trace elements (including U, Sr, and Mn), and stable water isotopes (δ2H and δ18O). Analyses for methyl Hg, solutes, and tritium (3H) are still underway. Preliminary results indicate that snowmelt and glacier melt was a significant source of total Hg, but additional work is needed to determine the extent of Hg methylation in the proglacial streams. Other trace elements were found in low concentrations in the melt water, but increased substantially downstream of the glaciers due to water-rock interactions.