NSFGEO-NERC:Collaborative Research: Chemistry and Biology under Low Flow Hydrologic Conditions Beneath the Greenland Ice Sheet Revealed through Naturally Emerging Subglacial Water

该项目由国家科学基金会地球科学理事会(NSF/GEO)和英国国家环境研究理事会(UKRI/NERC)通过NSF/GEO-NERC牵头机构协议共同资助。该协定允许美国和英国提交一个单一的联合提案，并由该机构进行同行审查，该机构的调查员在预算中所占比例最大。在成功联合确定奖项后，每个机构将为预算和调查人员提供与其各自工作相关的比例的资金。风化是一个重要的过程，从地球表面的岩石和矿物中释放出生命所必需的营养物质。该项目试图了解大冰川对格陵兰冰盖下风化过程的影响及其对生命的影响。在夏季，营养物质和其他产品被融化的冰中的水从格陵兰冰盖冲走。虽然这些产品在春季和夏季进行了采样，但尚不清楚冬季的气候变化过程有何不同。在这个项目中，研究人员将在冰冻的月份对格陵兰的两个冰川出口Isunnguata Seria和Leverett Glacier前形成的季节性冰进行采样，以评估反映冰盖下冬季条件的化学和微生物过程-新鲜融水输入最少的时期。这些样本将增加对格陵兰冰盖下冬季条件的了解，并有助于更好地了解基本上无法进入的冰盖内部部分。这些信息将有助于评估过去的情况，当时较冷的大气条件导致通过冰盖和冰床的融水输入最少。这些分析将有助于理解冰川在地球营养循环中的作用，无论是在过去的冰河时代条件下，还是在未来的冰川消融世界中。格陵兰冰盖是世界海洋生物重要元素的主要出口国。然而，我们对冰盖的化学和生物通量的大部分知识来自夏季出口冰川的外流，其通道化的水只接触冰川床的有限部分。冰川-河床界面的大部分包含缓慢流动的、分布的水，这并不代表这种流动。该项目将检验这样一种假设，即格陵兰冰盖出口下的越冬化学和生物过程与夏季的流出过程有很大不同，并代表着一个了解广泛但通常无法进入的分布流的窗口。主要的样品采集方法将是对冬季冰下流动在冰川末端形成的NALED冰进行早春取芯。这种流动的化学、矿物学和生物成分将与从融化季节的初始、高峰和末期涌出的物质进行比较。在北极其他地方，即使与第一次春季融化相比，冰下冰下冻结物质的化学成分在氧气或沉积物供应方面也显示出显著的限制，这支持了NALED冰揭示了一个独特的越冬系统的观点。将在两年内对Isunnguata Sermia和Leverett冰川的NALED冰和流出的冰川进行采样。这些西格陵兰岛的出口在它们排放的集水区的大小上存在超过一个数量级的差异，从而测试了规模对生物地球化学的影响。NALED的冰结构将通过探地雷达和冰孔温度分布来表征。将评估水的地球化学、碳酸盐和硫酸盐的稳定同位素，以及冰和水的悬浮沉积物的矿物学。这些分析将记录在冬季低流量条件和夏季融化高峰期之间冰川床矿物通量和大气气体供应的变化。还将测量微生物丰度、多样性、生物的元基因组学和稳定同位素，以了解地球化学条件和生物群落之间的伴生关系。研究人员将把研究成果纳入一系列推广工作中，包括为地球与环境科学中心开发一个新的课程模块，为未被充分代表的学生提供研究机会，作为通向研究的桥梁计划的一部分，并为市场科学计划准备实践活动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own component of the work.Weathering is an important process that releases nutrients that are essential for life from rocks and minerals in the Earth’s surface. This project seeks to understand the effect of large glaciers on weathering processes beneath the Greenland Ice Sheet and the consequences for life. During summer, nutrients and other products are flushed out of the Greenland Ice Sheet with water from melting ice. While these products have been sampled in spring and summer, it is not known how weathering processes are different during winter. In this project, researchers will sample the seasonal ice that forms in front of two of Greenland’s glacial outlets, Isunnguata Sermia and Leverett Glacier, during the freezing months to assess the chemistry and microbiology processes that reflect wintertime conditions beneath the ice sheet – periods when input of fresh meltwater is minimal. These samples will increase knowledge of winter conditions under the Greenland Ice Sheet and help better understand the interior portions of the ice sheet which are largely inaccessible. Such information will help in assessing past conditions, when colder atmospheric conditions resulted in minimal meltwater input through the ice sheet and to the glacial bed. These analyses will inform understanding of the role of glaciers on earth’s nutrient cycles presently, under past ice age conditions, and in a future deglaciating world.The Greenland Ice Sheet is a major exporter of biologically important elements to the world’s oceans. However, most of our knowledge of chemical and biological fluxes from the ice sheet comes from the summer outflux of outlet glaciers whose channelized waters contact only a limited portion of the glacier bed. The majority of the glacier-bed interface contains slow-flowing, distributed waters not representative of this flux. The project will test the hypothesis that overwinter chemical and biological processes under outlets of the Greenland Ice Sheet differ substantially from summer outflow and represent a window into widespread, but typically inaccessible, distributed flow. The principal sample collection method will be early spring coring of naled ice that forms at glacial termini from wintertime subglacial flow. Chemical, mineralogical, and biological constituents of this flow will be compared to material emerging from the initial, peak, and terminal phases of the melt season. Elsewhere in the Arctic, the chemistry of frozen overwinter subglacial material shows significant limitation in oxygen or sediment supply compared with even the first spring melt, supporting the idea that naled ice reveals a unique overwinter system. The naled ice and outflow of Isunnguata Sermia and Leverett Glacier will be sampled over two years. These West Greenland outlets differ by more than an order of magnitude in the size of the catchments they drain, thereby testing the effect of scale on biogeochemistry. Naled ice structure will be characterized by ground penetrating radar and ice borehole temperature profiles. The aqueous geochemistry, stable isotopes of carbonate and sulphate, and mineralogy of the suspended sediment of ice and water will be assessed. These analyses will document changes in the mineral flux and supply of atmospheric gases at the glacial bed between winter low flow conditions and peak summer melt. Microbial abundance, diversity, metagenomics, and stable isotopes of biomass will also be measured to understand the concomitant relationship between geochemical conditions and biological communities. Researchers will incorporate findings into a number of outreach efforts including developing a new curriculum module for the Center for Earth and Environmental Sciences, providing research opportunities for underrepresented students as part of the Bridge to Research Program and preparing hands-on activities for the Market Science Program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.