Preprints
https://doi.org/10.5194/tc-2016-59
https://doi.org/10.5194/tc-2016-59

  06 Apr 2016

06 Apr 2016

Review status: this preprint has been withdrawn by the authors.

Stable isotopic evidence for high microbial nitrate throughput in a High Arctic glacial catchment

A. H. Ansari1,2 A. H. Ansari
  • 1Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow – 226007, India
  • 2Department of Geography, University of Sheffield, Sheffield, S10 2TN, UK

Abstract. During summer, streams in the Arctic redistribute and export the solute derived from snowpack (accumulated by atmospheric deposition) melting and sediment weathering in its flowpath. The redistribution of dissolved nitrogen undergoes biogeochemical processing (nitrate production and consumption in flowpath). To assess the quantitative impact of these processing, NO3-N, NH4+-N, total dissolved nitrogen (TDN) and stable isotope composition of the snowpacks was compared with the subglacial and proglacial stream waters. Snowpack derived dissolved organic nitrogen (DON) and NH4+-N provided the most probable substrate for additional NO3-N produced by microbial nitrification. The flux of microbially produced and assimilated NO3-N in the eastern and western proglacial streams were 1.64 ± 1.41 kg Day−1 and 1.41 ± 1.43 kg Day−1 and, 1.39 ± 1.41 kg Day−1 and 1.35 ± 1.43 kg Day−1 respectively. These overwhelming amounts of NO3-N production and assimilation reveals a hitherto unknown level of microbial processing in the Arctic glacial ecosystem. The balance between the two microbial processes and consistently low dissolved inorganic nitrogen (NH4+-N + NO3-N) in the proglacial streams indicate a fast in-stream recycling of assimilated NO3-N however, the fate of such NO3-N remains unresolved.

This preprint has been withdrawn.

A. H. Ansari

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

A. H. Ansari

A. H. Ansari

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This preprint has been withdrawn.

Short summary
The solute chemistry and stable isotope investigation of the snowpack and stream samples demonstrates a large scale microbial NO3-N production (1.64 ± 1.41 kg Day−1 for MLE and 1.41 ± 1.43 kg Day−1 for MLW) and assimilation (1.39 ± 1.41 kg Day−1 for MLE and 1.35 ± 1.43 kg Day−1 for MLW) in the glacier catchment. The microbial nitrate production and consumption are several times higher than the actual nitrate flux of streams therefore infer that microbes play a much greater role in the glacial nitrogen.