Collaborative Research: Greenland Meltwater Geomicrobiology

The Greenland Ice Sheet (GrIS) is the largest freshwater reservoir in the Arctic. Melting of the GrIS is increasing, delivering large amounts of freshwater to the Arctic Ocean. The nature and composition of microbial communities below the GrIS are not known, but recent studies have documented the presence of viable microbial communities in other subglacial environments and within the GrIS ice itself, indicating their potential importance for chemical weathering processes. This project will characterize GrIS subglacial microbial communities to investigate the effect of microbes on lithospheric weathering and nutrient fluxes from the GrIS margin in West Greenland. The hypothesis is that the glacial thermal regime and bedrock lithology are the primary determinants of the subglacial bacterial communities, which in turn mediate nutrient release and weathering rates. Study sites in the Thule and Kangerlusuaq areas cover two major lithologies of West Greenland. The study combines state-of-the art microbiological, biogeochemical techniques, and datalogging of stream and climate parameters, to examine glacial meltwater. It is anticipated that the melting of the GrIS will have large effects on global biogeochemical cycles, ocean ecology, and atmospheric CO2. GrIS subglacial microbes are anticipated to play an important role in mobilizing elements from the lithosphere. Data generated on the diversity of GrIS microbes (Bacteria, Archaea and Eukarya) will provide an initial assessment of microbial richness and diversity in aquatic habitats beneath the GrIS. The primary objective is to examine the biodiversity and microbial contribution to geochemical processes and nutrient release, and this study will also provide insight into low temperature adaptation of life in and to a hitherto unexamined subglacial environment. A synergistic relationship with the WISSARD (Whillams Ice Stream Subglacial Access Research Drilling) project will provide the opportunity for a bipolar comparison of biodiversity beneath the Greenland and West Antarctic ice sheets. Providing data of chemical composition and fluxes of meltwater (particularly carbon, iron and trace nutrients) and sediments released by the GrIS will provide a framework to assess potential feedbacks in global biogeochemical models. Detailed measurements over two melting seasons will provide fundamental data towards a conceptual model of GrIS subglacial microbial environments.

格陵兰冰盖（Greenland Ice Sheet, GrIS）是北极地区规模最大的淡水储库。格陵兰冰盖的消融速率持续攀升，正向北冰洋输入海量淡水。目前学界对格陵兰冰盖下微生物群落的本质与组成仍缺乏系统认知，但近期已有研究在其他冰下环境以及格陵兰冰盖自身冰层中，证实了存活微生物群落的存在，这暗示了它们在化学风化过程中可能扮演的关键角色。本项目将对格陵兰冰盖冰下微生物群落进行系统性特征解析，以探究微生物对西格陵兰地区格陵兰冰盖边缘岩石圈风化过程以及营养盐通量的影响。本研究提出的核心假说为：冰川热状况与基岩岩性是调控冰下细菌群落组成的主要因素，而细菌群落反过来会介导营养盐释放与风化速率。本研究的选址覆盖西格陵兰的图勒（Thule）与康格鲁苏阿克（Kangerlusuaq）两个区域，囊括了当地两种主要的基岩岩性。本研究结合顶尖的微生物学与生物地球化学技术，以及溪流与气候参数的原位数据记录方案，对冰川融水开展系统性观测分析。据预测，格陵兰冰盖的消融将对全球生物地球化学循环、海洋生态系统以及大气二氧化碳浓度产生深远影响。格陵兰冰盖冰下微生物预计将在活化岩石圈中的元素方面发挥重要作用。本研究获取的格陵兰冰盖微生物（细菌、古菌与真核生物）多样性数据，将首次评估格陵兰冰盖下方水生栖息地中的微生物丰富度与多样性水平。本研究的核心目标是探究生物多样性特征以及微生物对地球化学过程与营养盐释放的贡献，同时还将揭示生命在低温环境下的适应性机制，以及此前尚未被探索的冰下环境的生命生存特性。本项目将与WISSARD（Whillams Ice Stream Subglacial Access Research Drilling）项目开展协同合作，为对比格陵兰与西南极冰盖下方的生物多样性提供双极对照研究的契机。获取格陵兰冰盖释放的融水（尤其是碳、铁与微量营养盐）以及沉积物的化学组成与通量数据，将为评估全球生物地球化学模型中的潜在反馈机制提供科学框架。在两个消融季开展的详细观测数据，将为构建格陵兰冰盖冰下微生物环境的概念模型提供基础支撑数据。