Aqueous phase chemistry of mercury in the atmosphere: a kinetic study of the reaction Hg0 + •OH

2012-10-02T08:55:14Z (GMT) by Elisabeth Svensson
<p> </p> <div> <p>My (by now ancient) honors thesis (BSc in Chemistry): </p> <p> </p> <div> <p>Aqueous phase chemistry of mercury in the atmosphere: A kinetic study of the reaction Hg0 + •OH</p> </div> <p>Summary:<br></p> <p>Mercury is a global pollutant that has been used by mankind for thousands of years. This has led to extensive discharges into the environment, contaminating air, lakes and soils. Bio-methylation of oxidized mercury species results in the highly toxic methyl-mercury thereby making mercury a threat to both humans and animals. The biogeochemical cycling of mercury between different natural compartments is governed by redox processes in both gas- and aqueous phase.</p> <p> </p> <p>The understanding of these processes requires thorough knowledge of the involved redox reactions of mercury species. In this study, the oxidation rate of elemental mercury by hydroxyl radicals in aqueous phase has been re-determined, as the earlier reported values have shown differences. It was found that the rate constant for the reaction Hg<sup>0</sup> + <sup>·</sup>OH was (2.9 ± 0.6) x 10<sup>9</sup> M<sup>-1</sup>s<sup>-1</sup> at pH 4.1 and (4.8 ± 1.5) x 10<sup>9</sup> M<sup>-1</sup>s<sup>-1</sup> at pH 7.2. A possible reason for the difference in the rate constant at the two pH-values may be a parallel reduction of Hg(II) to Hg<sup>0</sup>. </p> </div> <p><br> </p>