Heterogeneous reaction of gaseous ozone with aqueous iodide in the presence of aqueous organic species.

The fast reaction of gaseous ozone, O(3)(g), with aqueous iodide, I(-)(aq), was found to be affected by environmentally relevant cosolutes in experiments using cavity ring-down spectroscopy (CRDS) and electrospray ionization mass spectrometry (ESIMS) for the detection of gaseous and interfacial products, respectively. Iodine, I(2)(g), and iodine monoxide radical, IO(g), product yields were suppressed in the presence of a few millimolar phenol (pK(a) = 10.0), p-methoxyphenol (10.2), or p-cresol (10.3) at pH > or = 3 but unaffected by salicylic acid (pK(a(2)) = 13.6), tert-butanol, n-butanol, or malonic acid. We infer that reactive anionic phenolates inhibit I(2)(g) and IO(g) emissions by competing with I(-)(aq) for O(3)(g) at the air/water interface. ESIMS product analysis supports this mechanism. Atmospheric implications are discussed.