Warming stimulates sediment denitrification at the expense of anaerobic ammonium oxidation

• Published in: Nature climate change Vol. 10; no. 4; pp. 349 - 355
• Main Authors: Tan, Ehui, Zou, Wenbin, Zheng, Zhenzhen, Yan, Xiuli, Du, Moge, Hsu, Ting-Chang, Tian, Li, Middelburg, Jack J., Trull, Thomas W., Kao, Shuh-ji
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2020; Nature Publishing Group
• Subjects: 704/106/47; 704/106/694; 704/106/829; 704/158/2165; 704/47; Ammonium; Ammonium compounds; Anaerobic microorganisms; Climate Change; Climate Change/Climate Change Impacts; Denitrification; Earth and Environmental Science; Environment; Environmental Law/Policy/Ecojustice; Global warming; Greenhouse gases; Latitude; Nitrogen removal; Nitrous oxide; Oxidation; Sediment; Sediments; Summer temperatures; Temperature; Thermophilic bacteria
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-020-0723-2

Temperature is one of the fundamental environmental variables governing microbially mediated denitrification and anaerobic ammonium oxidation (anammox) in sediments. The GHG nitrous oxide (N 2 O) is produced during denitrification, but not by anammox, and knowledge of how these pathways respond to global warming remains limited. Here, we show that warming directly stimulates denitrification-derived N 2 O production and that the warming response for N 2 O production is slightly higher than the response for denitrification in subtropical sediments. Moreover, denitrification had a higher optimal temperature than anammox. Integrating our data into a global compilation indicates that denitrifiers are more thermotolerant, whereas anammox bacteria are relatively psychrotolerant. Crucially, recent summer temperatures in low-latitude sediments have exceeded the optimal temperature of anammox, implying that further warming may suppress anammox and direct more of the nitrogen flow towards denitrification and associated N 2 O production, leading to a positive climate feedback at low latitudes. Nitrogen removal occurs primarily through microbially mediated denitrification, which produces the GHG N 2 O, and anaerobic ammonium oxidation (anammox), which does not. Warming stimulates denitrification relative to annamox in subtropical sediments, indicating that warming could lead to greater N 2 O production.