ABSTRACT OCE-9811208 / 9815190 / 9815179 / 9815187 The well-lit surface waters of the world ocean is a region of material exchange with the atmosphere as well as a region characterized by a myriad of chemical reactions, many of which are driven by sunlight. In this project, the nvestigators will quantify and model the diel cycling of carbonyl sulfide, carbon monoxide, and hydrogen peroxide in the upper ocean. All three species are generated by solar photolysis of colored dissolved organic matter. High resolution determinations of these three species will be made at sea together with appropriate optical, biological, and meterological measurements. Laboratory experiments and mathematical models would be used to constrain the possible mechanisms of interconversion and to estimate unmeasured fluxes. The investigators expect to achieve an unprecedented understanding of the chemistry of these globally-important chemical species in the sea as well as their exchange between the ocean and lower atmosphere.