This project is a study of air/sea exchange and tropospheric chemistry of biogenic trace gases over the oceans. The first phase of the study is on a shipboard field experiment to determine the diurnal variations of sulfur gases (DMS, CS2, H2s, and SO2) in the marine boundary layer in order to estimate rates of emission and atmospheric oxidation. This scientific team will work collaboratively with other research groups to investigate the relationship between gas phase chemistry and the chemical and physical characteristics of the marine aerosol. The field work will be carried out in the eastern South Pacific ocean. The cruise will be a multi-investigator experiment and is a component of the MAGE/IGAC (Marine Aerosol and Gas Experiment/International Global Atmospheric Chemistry) Program.