The effects of dissolved organic matter on alkyl nitrate production during GOMECC and laboratory studies

Oceanic alkyl nitrates are important to the atmospheric reactive nitrogen cycle however, the sources of alkyl nitrates in the oceans are not well-understood. Photochemical production rates of alkyl nitrates were determined during the Gulf of Mexico East Coast Carbon Cruise (GOMECC). During this study, it was discovered that the relative production of alkyl nitrates may be influenced by coastal proximity with methyl and isopropyl nitrate production increasing relative to ethyl nitrate production in coastal waters. As a result of this observation, laboratory studies were carried out to determine alkyl nitrate production rates in the presence of Suwannee River humic and fulvic substances. As in the field experiments, methyl and isopropyl nitrate production increased in comparison to ethyl nitrate, suggesting that the source of dissolved organic matter affects relative alkyl nitrate production. This observation may be useful in quantifying the relative production of organic peroxy radicals from DOM as well as providing further insight into the factors that influence oceanic alkyl nitrate formation.