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

2012年，多方面的证据表明，格陵兰冰盖（GrIS）的淡水释放量创纪录，格陵兰冰盖是北方半球最大的冰川冰，也是北大西洋和北冰洋周围融水和相关物质的主要来源。7月8日至12日，卫星估计的冰盖表面融化量从40%增加到97%。这种变暖引起了媒体的广泛关注和公众的兴趣，但科学界缺乏对冰盖运动的融水控制和融水地球化学的直接观察，以应对如此大规模的融化事件。该RAPID提案的总体目标是在短期内量化大规模融化事件对格陵兰西部边缘大型陆地终止冰川的冰盖动态和融水地球化学的影响。RAPID基金将能够分析和合成一个独特的样本集收集在其他实地工作从莱弗里特冰川流域，一个大的出口冰川，通过一个单一的冰前河排放。虽然重点是2012年的事件，但研究人员还将分析两个实地季节（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驱动的变化。研究人员将使用时间序列放射性同位素（铍-7和氡-222）和稳定同位素（氧和氢），每种同位素都具有独特的来源和恒定的生产率，来自Leverett冰川流域，以区分来自最近的地表雪，冰川冰和延迟流动融水的融水部分。他们还将调查冰下环境释放的营养物质和金属通量的组成和大小，并研究这些通量在2012年7月期间如何演变。从2011-12年开始，PI和来自英国大学的同事收集了平行的冰盖地球物理数据（GPS，卫星图像）和融水地球化学样本（碳，宏观和微观营养素）。该项目将完全资助一个博士学位。学生，高中生和本科生实习生将被招募，以协助实验室方面的研究。为了提高该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向广大读者提供。最后，博士。学生将继续报告这项研究的结果，通过一个探险博客称为？在冰？（http：//blogs.scientificamerican.com/expeditions/tag/following-the-ice/）。

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/).