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

• Published in: Scientific Reports
• Main Authors: Hayashi, Kentaro, Tanabe, Yukiko, Ono, Keisuke, Loonen, Maarten J. J. E., Asano, Maki, Fujitani, Hirotsugu, Tokida, Takeshi, Uchida, Masaki, Hayatsu, Masahito
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: NITROUS-OXIDE N2O; ACETYLENE INHIBITION; AMMONIA EMISSIONS; TUNDRA; SOIL; ECOSYSTEM; METHANE; MICROORGANISMS; TEMPERATURE; DIVERSITY; Arctic; Svalbard; Tundra
• Online Access: https://hdl.handle.net/11370/826081e8-fd3d-4f27-9c7c-cc75cb5b7330; https://research.rug.nl/en/publications/826081e8-fd3d-4f27-9c7c-cc75cb5b7330; https://doi.org/10.1038/s41598-018-35669-w; https://pure.rug.nl/ws/files/76703327/s41598_018_35669_w.pdf

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-Alesund, Svalbard, in the European High Arctic. Talus soils at both locations had very high denitrification potentials at 10 degrees C (2.62-4.88 mg N kg(-1) dry soil h(-1)), near the mean daily maximum air temperature in July in Ny-Alesund, with positive temperature responses at 20 degrees 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 mu g N m(-2) h(-1)). Rapid nitrogen turnover at BL was supported by lower carbon-to-nitrogen ratios, higher nitrate content, and higher delta N-15 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.