|Title||Bacteria-driven production of alkyl nitrates in seawater|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Kim MJ, Michaud J.M, Williams R., Sherwood B.P, Pomeroy R., Azam F, Burkart M., Bertram TH|
|Journal||Geophysical Research Letters|
|Type of Article||Article|
|Keywords||air-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.