Carbonyl sulfide hydroxyl radical reaction

Most of the releases of carbonyl sulfide to the environment are to air, where it is believed to have a long residence time. The half-life of carbonyl sulfide in the atmosphere is estimated to be 2 years. It may be degraded in the atmosphere via a reaction with photochemically produced hydroxyl radicals or oxygen, direct photolysis, and other unknown processes related to the sulfur cycle. Sulfur dioxide, a greenhouse gas, is ultimately produced from these reactions. Carbonyl sulfide is relatively unreactive in the troposphere, but direct photolysis may occur in the stratosphere. Also, plants and soil microorganisms have been reported to remove carbonyl sulfide directly from the atmosphere. Plants are not expected to store carbonyl sulfide. 

Sulfur cycling is affected in a variety of ways, including UV photoinhibition of organisms such as bacterioplankton and zooplankton that affect sources and sinks of DMS and UV-initiated CDOM-sensitized photoreactions that oxidize DMS and produce carbonyl sulfide. Metal cycling also interacts in many ways with UVR via direct photoreactions of dissolved complexes and of metal oxides and indirect reactions that are mediated by photochemically-produced ROS. Photoreactions can affect the biological availability of essential trace nutrients such as iron and manganese, transforming the metals from complexes that are not readily assimilated into free metal ions or metal hydroxides that are available. Such photoreactions can enhance the toxicity of metals such as copper and can initiate metal redox reactions that transform non-reactive ROS such as superoxide into potent oxidants such as hydroxyl radicals. 

Carbon disulfide reacts with hydroxyl radicals in the troposphere to produce carbonyl sulfide (Cox and Sheppard 1980). The lifetime of carbon disulfide in the troposphere, assuming a reaction rate constant of 4.3 x 10"13 cm3 molecule 1, is 73 days (uncertain) other estimates (assuming different reaction rate constants) range from less than 1 week to more than 10 weeks (Cox and Sheppard 1980 EPA 1978a ... 

Atkinson R, Perry RA, Pitts JN Jr. 1978. Rate constants for the reaction of hydroxyl radicals with carbonyl sulfide, carbon disulfide and dimethyl thioether over the temperature range 299-430 K. Chem Phys Lett 54 14-18. 

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