CO2 evasion from the Greenland ice sheet

格陵兰岛的淡水径流总量位居世界第12和第13大河流之列，但对其地球化学的分析却出人意料地稀少。没有足够的数据来确定目前发生了什么碳循环反馈，以及它们未来可能会如何变化。初步研究表明，排干格陵兰冰盖的河流产生了以前未知的二氧化碳进入大气的通量：从西格陵兰罗素冰川下方涌出的水的二氧化碳分压是大气平衡的3至10倍，可能源于冰下微生物的新陈代谢。尽管在下游运输过程中通过化学风化消耗二氧化碳，但其中一些二氧化碳逃逸到大气中。关键问题涉及随着冰盖在变暖的世界中消融，二氧化碳逃逸是否会增加、如何减少，以及会在多大程度上增加或减少。通过季节性抽样和有针对性的假设检验，该项目旨在提高对现代过程的理解。这项工作将集中于Akuliarusiarsuup Kuua河从源头到下沉的特征，从它的发源地罗素冰川的末端到它在坎格卢斯苏阿克峡湾源头的入海口。其目的是测量和模拟pH值、主要离子、溶解有机碳、碳酸盐系统参数和溶解无机碳的碳同位素组成的下游梯度。此外，水的氧和氢同位素组成将被用来识别水源和流动路径，溶解的无机和有机碳的放射性碳含量将制约碳的年龄。这些数据将被用来检验五个假说，这些假说旨在阐明微生物活动、水文过程和化学风化如何调节二氧化碳逃逸的程度。除了教授和培训博士研究生外，PI还将为本科生研究人员提供建议，这些研究人员将进行实地考察并撰写高级荣誉论文。国际和平协会和他的学生团体还将让K-12代表人数不足的少数群体参加教育和宣传活动，说明温室效应及其与拟议研究的关系。

Total freshwater runoff from the Greenland ranks among the 12th and 13th largest rivers of the world, yet analyses of its geochemistry are surprisingly sparse. Insufficient data are available to identify what carbon cycle feedbacks presently occur and how they might change in the future. Preliminary research suggests that rivers draining the Greenland Ice Sheet yield a previously unknown flux of CO2 to the atmosphere: water emerging from beneath the Russell Glacier in West Greenland has CO2 partial pressures 3 to 10 times supersaturated with respect to atmospheric equilibrium, likely originating from subglacial microbial metabolism. Despite consumption through chemical weathering during downstream transport, some of this CO2 evades to the atmosphere. Key questions concern if, how, and to what extent CO2 evasion will either increase or decrease as the ice sheet decays in a warmer world. Through seasonal samplings and targeted hypothesis testing, this project aims to improve understanding of modern-day processes. The work would focus on a source-to-sink characterization of the Akuliarusiarsuup Kuua River, from its origin at the terminus of the Russell Glacier to its mouth at the head of the Kangerlussuaq Fjord. The objective is to measure and model downstream gradients for pH, major ions, dissolved organic carbon, carbonate system parameters, and the carbon isotope composition of dissolved inorganic carbon. In addition, the oxygen and hydrogen isotope composition of water will be used to identify water sources and flow paths, and the radiocarbon content of dissolved inorganic and organic carbon will constrain the age of the carbon. These data would be used to test five hypotheses designed to elucidate how microbial activity, hydrologic processes, and chemical weathering regulate the magnitude of CO2 evasion. In addition to teaching and training a Ph.D. graduate student, the PI would advise undergraduate student researchers who would conduct fieldwork and write senior honors theses. The PI and his student group would also engage K-12 underrepresented minorities in education and outreach activities illustrating the greenhouse effect and its relationship to the proposed study.