The production of gas-phase molecular iodine by the photoenhanced reaction between chlorophyll and iodide at salt water surfaces
Abstract
Sources of iodine species into the atmosphere are of interest because iodine atoms play an important role in the oxidative capacity of the troposphere and the formation of particles. Previous results from our group show that photoreactions between chlorophyll and halide salts at salt water surfaces may be an important source of reactive halogens into the troposphere. The mechanism for this reaction involves the reduction of photo-produced chlorophyll cations by a halide, producing a halogen atom. Of the halide species studied, iodide is most readily oxidized in aqueous media, and iodine atoms are the least reactive with organics. The production of iodine atoms is thus expected to result in the formation of molecular iodine rather than organoiodide compounds. We have used absorption spectroscopy to measure gas-phase iodine molecules formed during the illumination of iodide-containing solutions with chlorophyll at the surface. This technique has also been used to measure gas-phase iodine produced by reacting gaseous ozone with sodium iodide solutions. The chlorophyll-mediated photoreaction produces small but measurable amounts of gas-phase molecular iodine, confirming this as a potentially important source for iodine into the troposphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A21B0144R
- Keywords:
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- 0322 ATMOSPHERIC COMPOSITION AND STRUCTURE / Constituent sources and sinks;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 3307 ATMOSPHERIC PROCESSES / Boundary layer processes;
- 4504 OCEANOGRAPHY: PHYSICAL / Air/sea interactions