This Small Grants for Exploratory Research (SGER) project involves the deployment of a newly developed instrument aboard a research cruise vessel (R/V Wecoma) in the North Pacific Ocean region in the spring and early summer of 2004. This cruise of opportunity, from Guam to Oregon via Hawaii, is dedicated to understanding the exchange of organic halogen compounds between the ocean and the atmosphere. This project will involve first measurements of the dihalogen gases, chlorine (Cl2), bromine (Br2), iodine (I2), bromochlorine (BrCl), and iodochlorine (ICl), over the open ocean. The measurement method is based on atmospheric pressure chemical ionization mass spectrometry (API/CIMS), variants of which have been demonstrated by other researchers to be extremely sensitive and selective for atmospheric trace components. These first measurements, if successful, will provide valuable information on the role of these gases impact on the chemistry of ozone, hydrocarbons and sulfur compounds in the marine boundary layer, and could substantially revise our understanding of atmospheric photochemistry in this region. A second, even more exploratory measurement involves the quantification of the halogen oxides, ClO and BrO, using chemical conversion to species (deuterated haloacetones) that can be measured by API/CIMS.
The broader impacts of this research include providing field research experience for two graduate students and one post-doctoral fellow. In addition, this research contributes to the goals of the Surface Ocean Lower Atmosphere Study (SOLAS) program by helping to understand the composition of the marine atmospheric boundary layer and provide constraints on exchange of these gases with the ocean surface layer. In the longer view, this research will improve understanding of the oxidation processes operative in the marine boundary layer, and thus will better constrain the fate and lifetime of gases important for the earth's climate.
