Seabird-affected taluses are denitrification hotspots and potential N2O emitters in the High Arctic

Kentaro Hayashi, Yukiko Tanabe, Keisuke Ono, Maarten J.J.E. Loonen, Maki Asano, Hirotsugu Fujitani, Takeshi Tokida, Masaki Uchida, Masahito Hayatsu

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Abstract

In High Arctic tundra ecosystems, seabird colonies create nitrogen cycling hotspots because of bird-derived labile organic matter. However, knowledge about the nitrogen cycle in such ornithocoprophilous tundra is limited. Here, we determined denitrification potentials and in-situ nitrous oxide (N2O) emissions of surface soils on plant-covered taluses under piscivorous seabird cliffs at two sites (BL and ST) near Ny-Ålesund, Svalbard, in the European High Arctic. Talus soils at both locations had very high denitrification potentials at 10 °C (2.62–4.88 mg N kg−1 dry soil h−1), near the mean daily maximum air temperature in July in Ny-Ålesund, with positive temperature responses at 20 °C (Q10 values, 1.6–2.3). The talus soils contained abundant denitrification genes, suggesting that they are denitrification hotspots. However, high in-situ N2O emissions, indicating the presence of both active aerobic nitrification and anaerobic denitrification, were observed only at BL (max. 16.6 µg N m−2 h−1). Rapid nitrogen turnover at BL was supported by lower carbon-to-nitrogen ratios, higher nitrate content, and higher δ15N values in the soils at BL compared with those at ST. These are attributed to the 30-fold larger seabird density at BL than at ST, providing the larger organic matter input.

Original languageEnglish
Article number17261
JournalScientific Reports
Volume8
Issue number1
DOIs
Publication statusPublished - 2018 Dec 1

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Hayashi, K., Tanabe, Y., Ono, K., Loonen, M. J. J. E., Asano, M., Fujitani, H., Tokida, T., Uchida, M., & Hayatsu, M. (2018). Seabird-affected taluses are denitrification hotspots and potential N2O emitters in the High Arctic. Scientific Reports, 8(1), [17261]. https://doi.org/10.1038/s41598-018-35669-w