Temperature dependent kinetics of the reaction of ozone with iodide Journal Article uri icon



  • <p>Iodine in the atmosphere results from emissions of precursors from the oceans [1, 2] and undergoes continuous multiphase cycling. This cycling also prevents poorly soluble gaseous iodine species from removal by wet deposition. Thus, tropical convective outflow can even inject inorganic iodine into the lower stratosphere [3]. In the troposphere [1] and in the stratosphere [4], iodine appears in the gas- and particulate phase. In both compartments, particulate iodine exists not only in oxidized (as iodate) but also in reduced (as iodide) form [1, 4]. As iodide reacts with ozone in the aqueous phase [2] (which is also a major process related to iodine emission from the oceans), the reaction of ozone with iodide is one wheel of the cycles in the troposphere and may even represent a direct ozone sink in the stratosphere. However, only few kinetic data exist for this reaction. The temperature dependence of the reaction rate coefficient between 275 and 293 K was determined once and extrapolation of its value below 275 K rely on an activation energy estimate with an error of about 40 % [5]. Therefore, we performed laboratory experiments to extend the temperature range of the rate coefficient determination. We used a trough flow reactor [6] for our measurements and analyzed the data with a quasi steady state resistance model [7] to determine the essential physical parameters describing the reaction kinetics and their temperature dependence. Our results help to increase the understanding of atmospheric iodine chemistry and to better assess iodine’s impact on ozone in both, the troposphere and the stratosphere.</p><p>Bibliography<br>[1]          A. Saiz-Lopez et al., Chem. Rev., <strong>112</strong>, 3 (2012)<br>[2]          L. J. Carpenter et al., Nat. Geosci., <strong>6</strong> (2013)<br>[3]          A. Saiz-Lopez et al., Geophys. Res. Lett., <strong>42</strong>, 16 (2015)<br>[4]          T. K. Koenig et al., PNAS, <strong>117</strong>, 4 (2020)<br>[5]          L. Magi et al., J. Phys. Chem. A, <strong>101</strong> (1997)<br>[6]          L. Artiglia et al., Nat. Commun., <strong>8</strong> (2017)<br>[7]          M. Ammann et al., Atmos. Chem. Phys., <strong>13</strong> (2013)</p>

publication date

  • March 4, 2021

has restriction

  • closed

Date in CU Experts

  • March 5, 2021 3:50 AM

Full Author List

  • Gysin S; Roose A; Volkamer R; Peter T; Ammann M

author count

  • 5

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