| Summary: | This project assesses how weathering varies across deglacial 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 CO2 exchange. Deglacial watersheds are separated from the ice sheet by hydrologic divides and drain only annual snow and permafrost melt, while proglacial watersheds convey supraglacial and subglacial water to the ocean. Previous studies of high latitude weathering focused almost exclusively on proglacial and subglacial systems; however, preliminary work suggests deglacial watersheds in western Greenland transport similar volumes of water with higher solute concentrations than the proglacial system, and weathering extent increases from inland to the coast. Greenland Ice Sheet (GrIS) retreat will increase the areal extent of deglacial watersheds, particularly those with coastal weathering characteristics, thereby altering weathering fluxes. This project aims to test the hypothesis that differences in weathering reactions and extent within deglacial, and between deglacial 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 directly draining the Greenland Ice Sheet (proglacial rivers) and six streams draining deglaciated catchments that are disconnected from the ice (nonglacial streams). This dataset includes DOC and CDOM characteristics analyzed with spectroscopic (UV (ultraviolet) absorbance and fluorescence) measurements, biogeochemical solute concentrations, major cations and anions, trace metals, radiogenic isotopes, and stream discharge information.
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