RAPID: Impact of Large Scale Greenland Ice Sheet Melting on Glacier Hydrology and Meltwater Geochemistry

RAPID：大规模格陵兰冰盖融化对冰川水文学和融水地球化学的影响

• 批准号: 1256669
• 负责人: Matthew Charette
• 金额: $ 19.92万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1256669&HistoricalAwards=false
• 关键词: RAPID; Impact; Large; Scale; Greenland

In 2012, multiple lines of evidence suggest a record release of freshwater from the Greenland ice sheet (GrIS), the largest expanse of glacial ice in the Northern Hemisphere and a major source of meltwater and associated material to the surrounding North Atlantic and Arctic Oceans. Between July 8 and 12, satellite-derived estimates of surface melt increased from 40% to 97% of the ice sheet. This warming received widespread media attention and public interest, yet the scientific community lacks direct observations of meltwater controls on ice sheet movement and meltwater geochemistry for such a large-scale melting event. The overarching goal of this RAPID proposal is to quantify, in short order, the impact of a large-scale melting event on the ice sheet dynamics and meltwater biogeochemistry of a large, land-terminating glacier on the western Greenland margin. RAPID funds will enable the analysis and synthesis of a unique sample set collected during other fieldwork from the Leverett Glacier catchment, a large outlet glacier that discharges through a single proglacial river. Though the focus is on the 2012 episode, the investigators will also analyze samples and GrIS dynamics data from two field seasons (2011- 12), which will aid in interpretation of changes driven by the historic melting event owing to the highly contrasting annual freshwater discharge rates. The investigators will use time-series radiogenic (beryllium-7 and radon-222) and stable isotopes (oxygen and hydrogen), each with unique sources and constant production rates, from the Leverett glacier watershed to differentiate the fractions of meltwater sourced from recent surface snow, glacial ice and delayed flow meltwater. They will also investigate the composition and magnitude of nutrient and metal fluxes released from the subglacial environment and study how these fluxes evolved during July 2012. From 2011-12, parallel ice sheet geophysical data (GPS, satellite imagery) and meltwater biogeochemistry samples (carbon, macro- and micro-nutrients) have been collected by the PI and colleagues from universities in the United Kingdom. The proposed project will fully fund a Ph.D. student, and high school students and undergraduate interns will be recruited to assist with the laboratory aspect of the research. In order to increase the visibility of this project among the general public, the PI and student will co-author an article for the WHOI magazine Oceanus. This publication reaches a wide audience through both print- and web-based editions. Finally, the Ph.D. student will continue to report on the results of this study via an Expedition Blog called ?Following the Ice? on Scientific American (http://blogs.scientificamerican.com/expeditions/tag/following-the-ice/).

2012年，多项证据表明，格陵兰冰盖（GrIS）释放的淡水量创下了纪录。格陵兰冰盖是北半球面积最大的冰川，也是融水和相关物质流向北大西洋和北冰洋的主要来源。在7月8日至12日期间，卫星估算的冰盖表面融化从40%增加到97%。这种变暖得到了媒体的广泛关注和公众的兴趣，然而科学界缺乏对如此大规模融化事件的融水对冰盖运动的控制和融水地球化学的直接观察。这项RAPID计划的首要目标是在短期内量化大规模融化事件对格陵兰岛西部边缘一个大型陆地冰川的冰盖动力学和融水生物地球化学的影响。RAPID基金将用于分析和合成在其他野外工作中从莱弗里特冰川集水区收集的独特样本集，莱弗里特冰川集水区是一个通过一条前冰川河流排放的大型出口冰川。虽然重点是2012年的事件，但研究人员也将分析来自两个野外季节（2011- 12）的样本和GrIS动态数据，这将有助于解释由于年度淡水排放率差异很大而导致的历史性融化事件所导致的变化。研究人员将使用莱弗里特冰川流域的时间序列放射性成因（铍-7和氡-222）和稳定同位素（氧和氢），每一种同位素都有独特的来源和恒定的生产速率，以区分来自近期地表雪、冰川冰和延迟流动融水的融水部分。他们还将调查从冰下环境释放的营养物和金属通量的组成和大小，并研究这些通量在2012年7月期间是如何演变的。从2011年到2012年，PI和来自英国大学的同事们收集了平行的冰盖地球物理数据（GPS，卫星图像）和融水生物地球化学样本（碳，宏观和微量营养素）。拟议的项目将全额资助一名博士生，并将招募高中生和本科生实习生协助实验室方面的研究。为了提高这个项目在公众中的知名度，PI和学生将共同为WHOI杂志Oceanus撰写一篇文章。该出版物通过印刷版和网络版吸引了广泛的读者。最后，博士生将通过一个名为？的探险博客继续报告这项研究的结果。跟着冰走？在科学美国人（http://blogs.scientificamerican.com/expeditions/tag/following-the-ice/）上。