| Summary: | 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.
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