Hydrogeochemistry of Greenlandic proglacial and nonglacial streams, 2017-2018

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.

本研究旨在评估格陵兰西部与南部地区冰消流域（deglaciated watershed）和冰前流域（proglacial watershed）的风化作用差异，以评估冰盖退缩对海洋同位素与营养盐通量、大气二氧化碳（CO₂）及甲烷（CH₄）交换过程的影响。
冰消流域以水文分界线与冰盖相隔，汇纳降水与多年冻土融水；而冰前流域则额外包含冰川融水径流。
此前针对高纬度地区风化作用的研究几乎仅聚焦于冰前与冰下（subglacial）系统；但前期研究显示，格陵兰西部的冰消流域比流量（specific discharge，即归一化至汇水面积的径流量）与冰前流域相近，但溶质浓度存在显著差异。
这种溶质浓度差异源于从内陆到海岸的风化程度逐渐加深。
格陵兰冰盖（Greenland Ice Sheet, GrIS）退缩将扩大冰消流域的面积范围，尤其是具备海岸风化特征的流域，进而提升风化通量。
本研究旨在验证以下假说：冰消流域内部以及冰消与冰前环境之间的风化反应与风化程度差异，将随冰盖退缩导致同位素、溶质及营养盐通量出现可预测的变化。
本研究对比了2017年春季、秋季及2018年夏季融季期间，格陵兰地区两条汇水源自格陵兰冰盖的冰前河流与六条汇水源自冰消流域的非冰川溪流（nonglacial streams）的径流量与水化学特征。
本数据集涵盖主要阳离子、阴离子、生物地球化学溶质浓度、痕量金属、放射性同位素（radiogenic isotopes）、溶解性有机碳（Dissolved Organic Carbon, DOC）及有色溶解性有机物（Colored Dissolved Organic Matter, CDOM）的光谱分析（紫外吸收与荧光光谱）特征，以及径流量相关数据。