| Summary: | This project assesses how weathering varies across deglaciated and proglacial watersheds in western and southern Greenland to evaluate the impact of ice sheet retreat on isotopic and nutrient fluxes to the ocean and atmospheric carbon dioxide (CO 2 ) and methane (CH 4 ) exchange. Deglaciated watersheds are separated from the ice sheet by hydrologic divides and drain precipitation and permafrost meltwater, while proglacial watersheds include also glacial meltwater. Previous studies of high latitude weathering focused almost exclusively on proglacial and subglacial systems; however, preliminary work suggests deglaciated watersheds in western Greenland have similar specific discharge (discharge normalized to drainage area) but solute concentrations distinct from proglacial system. Distinct solute concentrations results from increasing weathering extent from inland to the coast. Greenland Ice Sheet (GrIS) retreat will increase the areal extent of deglaciated watersheds, particularly those with coastal weathering characteristics, and thus should weathering fluxes. This project aims to test the hypothesis that differences in weathering reactions and extent within deglaciated watershed, and between deglaciated and proglacial environments, will produce predictable changes in isotopic, solute, and nutrient fluxes as the ice sheet retreats. We compare stream discharge and water chemistry between Greenlandic proglacial and nonglacial streams during the spring (2017), summer (2018) and fall (2017) melt seasons between two rivers draining the Greenland Ice Sheet (proglacial rivers) and six streams draining deglaciated watersheds (nonglacial streams). This dataset includes major cations and anions, biogeochemical solute concentrations, trace metals, radiogenic isotopes, Dissolved Organic Carbon (DOC) and Colored Dissolved Organic Matter (CDOM) characteristics analyzed with spectroscopic (UV (ultraviolet) absorbance and fluorescence) measurement, and stream discharge information.
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