title: HONO emissions from soil bacteria as a major source of atmospheric reactive nitrogen.
abstract: 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.
authors.affiliation: Biogeochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany. robert.oswald@mpic.de
authors.forename: R
authors.initials: R
authors.lastname: Oswald
authors.forename: T
authors.initials: T
authors.lastname: Behrendt
authors.forename: M
authors.initials: M
authors.lastname: Ermel
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: H
authors.initials: H
authors.lastname: Su
authors.forename: Y
authors.initials: Y
authors.lastname: Cheng
authors.forename: C
authors.initials: C
authors.lastname: Breuninger
authors.forename: A
authors.initials: A
authors.lastname: Moravek
authors.forename: E
authors.initials: E
authors.lastname: Mougin
authors.forename: C
authors.initials: C
authors.lastname: Delon
authors.forename: B
authors.initials: B
authors.lastname: Loubet
authors.forename: A
authors.initials: A
authors.lastname: Pommerening-Röser
authors.forename: M
authors.initials: M
authors.lastname: Sörgel
authors.forename: U
authors.initials: U
authors.lastname: Pöschl
authors.forename: T
authors.initials: T
authors.lastname: Hoffmann
authors.forename: M O
authors.initials: MO
authors.lastname: Andreae
authors.forename: F X
authors.initials: FX
authors.lastname: Meixner
authors.forename: I
authors.initials: I
authors.lastname: Trebs
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001272:Atmosphere / Q000737:chemistry; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D043370:Nitrosomonas europaea / Q000378:metabolism*; D009608:Nitrous Acid / Q000378:metabolism*; D010084:Oxidation-Reduction; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D012988:Soil Microbiology
chemical_list: D026361:Reactive Nitrogen Species; D000641:Ammonia; D009584:Nitrogen; D009608:Nitrous Acid