Stimulation of elemental mercury oxidation in the presence of chloride ion in aquatic environments

The effect of chloride ion (Cl−) on the oxidation of elemental mercury (Hg0) in aqueous solution was studied. Oxidation of Hg0 to mercuric ion was found to be stimulated in the presence of sodium chloride in a dose- and time-dependent manner. The oxidation was also stimulated in the presence of potassium chloride, magnesium chloride or hydrochloric acid, suggesting the participation of Cl− in Hg0 oxidation. Oxidation rate of Hg0 in natural sea water was significantly higher than that in distilled water or natural fresh water. These results indicate that the Hg0 oxidation actually occur in natural aquatic environments, and Cl− would play an important role in the cycling of mercury there.