Bacteria-driven production of alkyl nitrates in seawater

TitleBacteria-driven production of alkyl nitrates in seawater
Publication TypeJournal Article
Year of Publication2015
AuthorsKim MJ, Michaud J.M, Williams R., Sherwood B.P, Pomeroy R., Azam F, Burkart M., Bertram TH
JournalGeophysical Research Letters
Date Published2015/01
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000349956000051
Keywordsair-sea exchange; atmospheric fate; bacteria; hydrogen-sulfide; marine; methyl nitrate; nitric-oxide; pacific-ocean; photochemical; production; radicals; reactive nitrogen; seasonal-variations; source; synthases; trace gases

Aircraft- and ship-borne measurements have shown that the ocean is a large, diffuse source for short chain (C-1-C-3) gas phase alkyl nitrates (RONO2). Photochemical production of RONO2 has been demonstrated previously as a viable mechanism in surface waters; however, it cannot account for the observed depth profile of RONO2, suggesting an additional, dark RONO2 production mechanism. We present measurements of gas phase C-1-C-5 alkyl nitrates emitted from seawater in a controlled mesocosm experiment conducted under low-light conditions in a glass-walled wave channel. Ethyl and butyl nitrate emission rates from seawater are strongly correlated with the abundance of heterotrophic bacteria (R(2)0.89) and show no correlation to chlorophyll a concentration. Controlled flask experiments conducted using ambient and sterile seawater, inoculated with a heterotrophic bacterium, confirm that bacterial driven production of select RONO2 can proceed efficiently in the absence of light.

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