Accession Number : ADA324011

Title :   Oxidation-Reduction Photochemistry in Marine Systems.

Descriptive Note : Final rept.,

Corporate Author : WOODS HOLE OCEANOGRAPHIC INSTITUTION MA

Personal Author(s) : Zafiriou, Oliver C.

PDF Url : ADA324011

Report Date : 19 MAR 1997

Pagination or Media Count : 12

Abstract : The principal net process in natural water photochemistry is light-catalyzed oxidation of a various organic compounds ('Dissolved Organic Carbon', DOC), with concurrent reduction of dissolved oxygen: DOC +02 + light right arrow oxidized DOC (e.g. CO, CO2, carbonyl compounds) + HOOH. We explored the hypothesis that HOOH forms by one electron reduction of oxygen to superoxide (O2(-)) which then 'dismutates' to HOOR. We also quantified 02(-) fluxes and defined some HOOH reaction paths. (1) 02(-) fluxes were quantified in two seasons in the eastern Caribbean; they correlated with total free radical fluxes and with runoff of the Orinoco and Amazon Rivers. (2) Isotopic methods were applied to characterize the slower chemical and biological decay of HOOH. (3) Pulse radiolysis fast-kinetics studies in seawater medium elucidated in detail the kinetics and nature of the dismutation (proton and Cu catalysis) that forms HOOH. (4) A method for directly measuring the steady-state in situ concentration (not flux) of O2(-)in sunlit surface waters was developed and deployed at sea on the R/V Columbus Iselin, which went hard aground on day 3; ONR declined to continue support. (5) A quantitative timeseries model of CO photochemistry was developed.

Descriptors :   *OCEAN SURFACE, *PHOTOCHEMICAL REACTIONS, *OXIDATION REDUCTION REACTIONS, *PEROXIDES, ISOTOPES, ORGANIC COMPOUNDS, CATALYSIS, HYPOTHESES, FREE RADICALS, SEA WATER, CARBONYL COMPOUNDS, SUPEROXIDES.

Subject Categories : Organic Chemistry
      Biological Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE