Conversion of Iodide to Hypoiodous Acid and Iodine in Aqueous Microdroplets Exposed to Ozone
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- 作者：Elizabeth A. Pillar ; Marcelo I. Guzman ; Jose M. Rodriguez
- 刊名：Environmental Science & Technology
- 出版年：2013
- 出版时间：October 1, 2013
- 年：2013
- 卷：47
- 期：19
- 页码：10971-10979
- 全文大小：419K
- 年卷期：v.47,no.19(October 1, 2013)
- ISSN：1520-5851
文摘
Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O3) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O3 and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O3 at variable iodide (I鈥?/sup>) concentration (0.010鈥?00 渭M) for solutions aerosolized at 25 掳C, which reveal remarkable differences in the reaction intermediates and products expected in sea spray for low tropospheric [O3]. The ultrafast oxidation of I鈥?/sup> by O3 at the air鈥搘ater interface of microdroplets is evidenced by the appearance of hypoiodous acid (HIO), iodite (IO2鈥?/sup>), iodate (IO3鈥?/sup>), triiodide (I3鈥?/sup>), and molecular iodine (I2). Mass spectrometry measurements reveal an enhancement (up to 28%) in the dissolution of gaseous O3 at the gas鈥搇iquid interface when increasing the concentration of NaI or NaBr from 0.010 to 100 渭M. The production of iodine species such as HIO and I2 from NaI aerosolized solutions exposed to 50 ppbv O3 can occur at the air鈥搘ater interface of sea spray, followed by their transfer to the gas-phase, where they contribute to the loss of tropospheric ozone.