REGIONAL VARIATIONS IN NITRATE CONTENT OF ROCK GLACIER OUTFLOW, COLORADO ROCKIES

As alpine ecosystems undergo widespread deglaciation, rock glaciers and periglacial features are becoming an increasingly critical water reservoir in headwater ecosystems. Thus, rock glacier outlet water chemistry has critical implications for ecosystem resiliency and downstream water quality under accelerating global change. These waters have been observed to contain extremely high nitrate concentrations, among the highest ever recorded in high elevation ecosystems. This has the potential to influence biogeochemical cycling in headwater ecosystems. Despite these potentially significant ecosystem impacts, sources of reactive nitrogen species in rock glacier outflow remain unknown. We compare concentrations and stable isotopes of nitrate in rock glacier outflow to surface water, groundwater, and snow samples. We examine variations in nitrate loading regionally between the San Juan mountains and the Front Range, locally within the San Juans, and seasonally at Imogene Rock Glacier. We hope to uncover potential reservoirs and fluxes of reactive nitrogen species in rock glacier-fed catchments.