CO2 evasion from the Greenland ice sheet

格陵兰冰盖的二氧化碳逃逸

• 批准号: 1304686
• 负责人: Andrew Jacobson
• 金额: $ 33.9万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1304686&HistoricalAwards=false
• 关键词: CO2; evasion; Greenland; ice; sheet

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.

格陵兰的淡水径流总量在世界上排名第12位和第13位，然而对其地球化学的分析却少得惊人。目前还没有足够的数据来确定目前发生了哪些碳循环反馈以及它们在未来可能如何变化。初步研究表明，从格陵兰冰原流出的河流向大气中产生了以前未知的二氧化碳通量：从西格陵兰拉塞尔冰川下流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代谢。尽管在下游运输过程中通过化学风化作用消耗了二氧化碳，但其中一些二氧化碳会逃逸到大气中。关键的问题是，随着世界变暖，冰盖的融化，二氧化碳的逃逸是否会增加或减少，如何增加，以及减少到什么程度。通过季节性采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。这项工作将集中在库瓦河从源头到汇的特征上，从它在拉塞尔冰川末端的源头到它在康克鲁斯瓦格峡湾顶端的河口。目的是测量和模拟下游pH、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梯度。此外，水的氧和氢同位素组成将用于识别水源和流动路径，溶解的无机碳和有机碳的放射性碳含量将限制碳的年龄。这些数据将用于测试五个假设，这些假设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幅度。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。PI和他的学生小组还将让K-12未被充分代表的少数民族参与教育和推广活动，说明温室效应及其与拟议研究的关系。