Japan Geoscience Union Meeting 2016

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Symbol A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG24] Science in the Arctic Region

Thu. May 26, 2016 1:45 PM - 3:15 PM 304 (3F)

Convener:*Takao Kawasaki(National Institute of Polar Research), Masato Mori(Atmosphere and Ocean Research Institute, University of Tokyo), Hisashi Sato(Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Shun Tsutaki(Arctic Environmental Research Center, National Institute of Polar Research), Hiroyasu Hasumi(Atmosphere and Ocean Research Institute, The University of Tokyo), Chair:Hisashi Sato(Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Shun Tsutaki(Arctic Environmental Research Center, National Institute of Polar Research)

2:45 PM - 3:00 PM

[ACG24-16] The sources of nitrogen and its effect on microbes on glacial snow and ice in the northwest Greenland

*Nozomu Takeuchi1, Nobuhito Ohte2, Naoko Nagatsuka3, Jun Uetake3, Sota Tanaka1, Yukihiko Onuma1 (1.Chiba University, 2.Kyoto University, 3.National Institute of Polar Research)

Keywords:Greenland, microbe, nitrogen

The quantity and distribution of insoluble impurities are one of the most significant factors to determine surface albedo and have been reported to affect substantial melting of glacier ice and snow. Supraglacial impurities usually consist of inorganic and organic material accreted on the ice surface by wet precipitation or aeolian deposition. Microbes and organic matter are also dominant biotic constituents of supraglacial impurities. Microbes include cold-tolerant snow and ice algae, cyanobacteria, and heterotrophic bacteria, and they can grow and proliferate on the melting snow or ice surfaces. These microbes and their derivative organic matter often aggregate with mineral particles and form spherical granules called cryoconite. Cryoconite and some pigmented algae usually display a higher light absorbency (i.e. dark colored) compared with pure snow and ice, thus they can efficiently reduce surface albedo of snow and ice. Nitrogen is one of the important nutrients supporting growth of such microbes, however, information on their sources and dynamics on the glacial systems is still limited. We report soluble nitrogen concentrations and the nitrate stable isotopes (18O and 15N) in snow, ice, and meltwater collected in the north-west Greenland Ice Sheet. Nitrate was contained in both of snow and glacial ice. O and N isotopes of the nitrate showed that nitrate in snow is mostly supplied from atmosphere derived from natural origin, while that in glacial ice is from anthropogenic origins. Nitrogen isotope in organic faction in the impurities coincided to that of snthoropogenic nitrogen, suggesting that that microbes on the glacier used mainly anthropogenic nitrogen.