GLACIER MELTWATER COMPOSITION AS AN INDICATOR OF SUBGLACIAL GEOTHERMAL ACTIVITY ONn MOUNT RAINIER, WA

We are analyzing meltwater from glaciers on Mount Rainier to locate areas of subglacial geothermal activity. Mount Rainier is a geothermally active, glaciated peak located about 50 miles south of Seattle, Washington. Several studies have shown that chemical analysis of glacial meltwater can be used to locate geothermally active areas beneath glaciers. We are collecting meltwater samples from glacial streams on the west and southwest flanks of Mount Rainier, where published data and previous work suggest subglacial geothermal influence. Meltwater analyses include pH, total suspended solids, sulfate, and dissolved inorganic and organic carbon. Preliminary data show that runoff in Tahoma Creek is slightly more acidic than other glacial streams on the mountain, possibly indicating geothermal activity beneath the Tahoma and South Tahoma Glaciers. We expect that additional analyses will yield elevated levels of sulfate in the same area, and possibly at other sites on the western side of the mountain. We are also identifying microbial life present in meltwater samples; given the reliance of microbial communities on meltwater constituents, the presence of certain microbes may also prove to be a valuable indicator of geothermal activity. We will analyze sequenced DNA of microbial life to identify any geographic patterns in microbial presence; we expect to find either an inclusive or exclusive pattern of species in meltwater where geothermal indicators are present. Future research may include testing a wider range of chemical constituents and more extensive sampling of glacial streams on Mount Rainier to create a more complete profile of the mountain’s geothermal activity.