Marine-dissolved organic matter (m-DOM) at the ocean surface is continuously transformed via microbial and abiotic processes, contributing to its chemical complexity. Although a subject of study for decades, it still poses an analytical challenge to characterize at the molecular level. Facilitating many photochemical reactions in the surface ocean, marine chromophoric dissolved organic matter (m-CDOM) makes up a small but significant fraction within the m-DOM pool. Recently, it has been shown that these chromophoric compounds can also get into sea spray aerosols produced at the air/ocean interface through bubble bursting. In this study, we investigate the composition of m-DOM across a mesocosm bloom as well as the photochemistry of m-DOM in the presence and absence of nitrate solutions. Products formed from the irradiation of m-DOM and nitrate include gas–phase nitrous acid (HONO) and nitrogen dioxide (NO<sub>2</sub>) and condense phase compounds. We show with high resolution Orbitrap mass spectrometry, that these condensed phase products are nitrogen-containing compounds. Overall, this study demonstrates a step forward in identifying and characterizing m-DOM using temporal mesocosm data and various spectroscopic techniques as well as the identification of new products formed upon irradiation in the presence of nitrates.

Changes in the composition of irradiated marine-dissolved organic matter in the presence of nitrates

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.