Continuous Underway Seawater Measurements of Biogenic Volatile Organic Compounds in the Western Atlantic Ocean

Thursday, 18 December 2014
Matthew Zoerb1, Michelle Kim2 and Timothy H Bertram1, (1)University of California San Diego, La Jolla, CA, United States, (2)Scripps Institution of Oceanography, La Jolla, CA, United States
The products of isoprene and terpene oxidation have been shown to contribute significantly to secondary aerosol production rates over continental regions, where the emission rates have been well characterized. Significantly less is known about the emission of isoprene and monoterpenes from marine sources. We discuss the development of a chemical ionization mass spectrometer (CIMS) employing benzene reagent ion chemistry for the selective detection of biogenic volatile organic compounds. The CIMS was coupled to a seawater equilibrator for the measurement of dissolved gases in surface seawater. This system was deployed aboard the R/V Knorr during the Western Atlantic Climate Study II in Spring 2014. Here, we report surface seawater (5 m depth) concentrations of dimethyl sulfide, isoprene, and alpha-pinene. The concentration measurements are discussed in terms of surface seawater temperature, nutrient availability, and primary productivity.