Hydroxylamine released by nitrifying microorganisms is a precursor for HONO emission from drying soils

TitleHydroxylamine released by nitrifying microorganisms is a precursor for HONO emission from drying soils
Publication TypeJournal Article
Year of Publication2018
AuthorsErmel M., Behrendt T., Oswald R., Derstroff B., Wu D., Hohlmann S., Stonner C., Pommerening-Roser A., Konneke M., Williams J., Meixner F.X, Andreae M.O, Trebs I., Sorgel M.
JournalScientific Reports
Date Published2018/01
Type of ArticleArticle
ISBN Number2045-2322
Accession NumberWOS:000423508900048
Keywordsaccumulation; acid; ammonia-oxidizing archaea; atmosphere; bacteria; nitrification; nitrosomonas; nitrous-oxide; oxidation-kinetics; ph; Science & Technology - Other Topics

Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH), the atmosphere's primary oxidant. An unknown strong daytime source of HONO is required to explain measurements in ambient air. Emissions from soils are one of the potential sources. Ammonia-oxidizing bacteria (AOB) have been identified as possible producers of these HONO soil emissions. However, the mechanisms for production and release of HONO in soils are not fully understood. In this study, we used a dynamic soil-chamber system to provide direct evidence that gaseous emissions from nitrifying pure cultures contain hydroxylamine (NH2OH), which is subsequently converted to HONO in a heterogeneous reaction with water vapor on glass bead surfaces. In addition to different AOB species, we found release of HONO also in ammonia-oxidizing archaea (AOA), suggesting that these globally abundant microbes may also contribute to the formation of atmospheric HONO and consequently OH. Since biogenic NH2OH is formed by diverse organisms, such as AOB, AOA, methane-oxidizing bacteria, heterotrophic nitrifiers, and fungi, we argue that HONO emission from soil is not restricted to the nitrifying bacteria, but is also promoted by nitrifying members of the domains Archaea and Eukarya.

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