UV photochemistry of carboxylic acids at the air‐sea boundary: A relevant source of glyoxal and other oxygenated VOC in the marine atmosphere. Issue 2 (18th January 2017)

• Record Type: Journal Article
• Authors: Chiu, R.; Tinel, L.; Gonzalez, L.; Ciuraru, R.; Bernard, F.; George, C.; Volkamer, R.
• Is Part Of: Geophysical research letters. Volume 44:Issue 2(2017)
• Page Start: 1079
• Page End: 1087
• Publication Date: 2017-01-18
• Subjects: sea surface microlayer -- carboxylic acids -- photochemistry -- dissolved organic carbon -- marine OVOC -- glyoxal; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL071240
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Photochemistry plays an important role in marine dissolved organic carbon (DOC) degradation, but the mechanisms that convert DOC into volatile organic compounds (VOCs) remain poorly understood. We irradiated carboxylic acids (C7 –C9 ) on a simulated ocean surface with UV light (<320 nm) in a photochemical flow reactor and transferred the VOC products into a dark ozone reactor. Glyoxal was detected as a secondary product from heptanoic, octanoic, and nonanoic acid (NA) films, but not from octanol. Primary glyoxal emissions were not observed, nor was glyoxal formed in the absence of ozone. Addition of a photosensitizer had no noticeable effect. The concurrent detection of heptanal in the NA system suggests that the ozonolysis of 2‐nonenal is the primary chemical mechanism that produces glyoxal. This source can potentially sustain tens of parts per trillion by volume (pptv) glyoxal over oceans, and helps to explain why glyoxal fluxes in marine air are directed from the atmosphere into the ocean. Key Points: UV irradiation of carboxylic acids is a source for unsaturated OVOCs, e.g., alkenals Glyoxal and aldehydes form as secondary products from gas phase ozonolysis of alkenals The mechanism explains why ambient glyoxal fluxes are directed into the ocean and adds a potentially significant marine source of OVOC