SOME AQUEOUS REACTIONS OF POTENTIAL IMPORTANCE IN THE ATMOSPHERIC CHEMISTRY OF MERCURY

Reactions of Hg(I) and Hg(II) with oxidizing and reducing agents have been investigated using stopped-flow and spectroscopic techniques. Hg2(2+) was found to be oxidized by HClO and radicals produced by Fentons reagent (Fe2+ + H2O2). The rate determining step in the reaction of Hg2(2+) and HClO is probably a relatively rapid reaction of Hg0 and HClO. A photochemically induced reduction of Hg(OH)2(aq) to Hg0 was observed when irradiating with simulated sunlight (lambda > 290 nm), which may be a process of environmental importance. Aqueous Hg(CN)2 and HgCl2 were found to be stable. The rate of reduction of Hg(SO3)2(2-) is not affected by irradiation. No oxidation of Hg2(2+) was found when mixing solutions containing H2O2 or Fe3+ or a mixture of the two which suggests that H2O2 is not an important oxidant for mercury under environmental conditions.