HONO Emissions from Soil Bacteria as a Major Source of Atmospheric Reactive Nitrogen

R. Oswald (1, 2) , T. Behrendt (1, 3) , M. Ermel (1, 2) , D. Wu (1, 4) , H. Su (5) , Y. Cheng (5) , C. Breuninger (1) , A. Moravek (1, 6) , Éric Mougin (7) , Claire Delon (8) , B. Loubet (9) , A. Pommerening-Röser (10) , M. Sörgel (1) , U. Poschl (5) , T. Hoffmann (2) , M.O. Andreae (1) , F. X. Meixner (1) , I. Trebs (1)

1 Biogeochemistry Department [Mainz]
2 Institute for Inorganic and Analytical Chemistry
3 Institute for Geography [Mainz]
4 Key Laboratory of Agricultural Water Research
5 Multiphase Chemistry Department [Mainz]
6 Micrometeorology Group [Bayreuth]
7 GET - Géosciences Environnement Toulouse
8 LAERO - Laboratoire d'aérologie
9 EGC - Environnement et Grandes Cultures
10 Department of Microbiology and Biotechnology

Abiotic release of nitrous acid (HONO) in equilibrium with soil nitrite (NO2-) was suggested as an important contributor to the missing source of atmospheric HONO and hydroxyl radicals (OH). The role of total soil-derived HONO in the biogeochemical and atmospheric nitrogen cycles, however, has remained unknown. In laboratory experiments, we found that for nonacidic soils from arid and arable areas, reactive nitrogen emitted as HONO is comparable with emissions of nitric oxide (NO). We show that ammonia-oxidizing bacteria can directly release HONO in quantities larger than expected from the acid-base and Henry's law equilibria of the aqueous phase in soil. This component of the nitrogen cycle constitutes an additional loss term for fixed nitrogen in soils and a source for reactive nitrogen in the atmosphere.

Mots clés: NITRIFICATION; NITRIC-OXIDE; DEPENDENCE; DENITRIFICATION; TEMPERATURE; RAIN-FOREST; SOUTH-AFRICA; NO EMISSIONS; WATER CONTENT; EMPIRICAL-MODEL

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

R. Oswald, T. Behrendt, M. Ermel, D. Wu, H. Su, et al.. HONO Emissions from Soil Bacteria as a Major Source of Atmospheric Reactive Nitrogen. Science, 2013, 341 (6151), pp.1233-1235. ⟨10.1126/science.1242266⟩. ⟨hal-00910702⟩