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

2012年，多种证据表明，格陵兰冰盖(GRI)的淡水释放达到了创纪录的水平，格陵兰冰盖是北半球最大的冰川，也是周围北大西洋和北冰洋融化水和相关物质的主要来源。在7月8日至12日期间，卫星对冰盖表面融化的估计从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如此大规模融化事件的融水地球化学的直接观察。这一快速提案的首要目标是在短时间内量化大规模融化事件对格陵兰西部边缘一座大型陆地冰川的冰盖动力学和融水生物地球化学的影响。快速资金将使分析和合成在其他实地调查期间从Leverett冰川集水区收集的独特样本集成为可能，Leverett Glacier集水区是一个大型出口冰川，通过单一的冰川河流排放。虽然重点放在2012年的事件上，但调查人员也将分析两个野外季节(2011-2012年)的样本和GRIS动态数据，这将有助于解释由于年度淡水排放速率的高度对比而导致的历史性融化事件所驱动的变化。研究人员将使用来自莱弗里特冰川分水岭的时间序列放射成因(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产生率，以区分来自最近地表积雪、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。2011-2012年期间，国际冰原研究所及其联合王国大学的同事收集了平行的冰盖地球物理数据(全球定位系统、卫星图像)和融水生物地球化学样品(碳、宏观和微观营养物质)。拟议的项目将为一名博士生提供全额资金，并将招募高中生和本科生实习生协助实验室方面的研究。为了提高这一项目在公众中的知名度，国际和平研究所和学生将共同为世界卫生组织杂志《海洋》撰写一篇文章。这份出版物通过印刷版和网络版接触到广泛的受众。最后，这位博士生将继续通过名为？跟随冰？的探险博客报告这项研究的结果。论《科学美国人》的(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/).