Received: 05 Mar 2016 – Accepted for review: 30 Mar 2016 – Discussion started: 06 Apr 2016
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This preprint has been withdrawn.
How to cite: Ansari, A. H.: Stable isotopic evidence for high microbial nitrate throughput in a High Arctic glacial catchment, The Cryosphere Discuss., https://doi.org/10.5194/tc-2016-59, 2016.
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.
The solute chemistry and stable isotope investigation of the snowpack and stream samples...