Volatilization of mercury under acidic conditions from mercury-polluted soil by a mercury-resistant Acidithiobacillus ferrooxidans SUG 2-2

Volatilization of mercury under acidic conditions from soil polluted with m ercuric chloride (1.5 mg Hg/kg soil) was studied with resting cells of a me rcury-resistant strain, Acidithiobacillus ferrooxidans SUG 2-2. When restin g cells of SUG 2-2 (0.01 mg of protein) were incubated for 10 d at 30 degre esC in 20 ml of 1.6 mm sulfuric acid (pH 2.5) with ferrous sulfate (3%) and mercury-polluted soil (1 g), which contained 7.5 nmol of Hg, approximately 4.1 nmol of mercury was volatilized, indicating that 54% of the total merc ury in the soil was volatilized. The amount of mercury volatilized from the soil was dependent on the concentration of Fe2+ added to the medium. When elemental sulfur, sodium tetrathionate, and pyrite were used as an electron donor for the mercury reduction, 16, 2.4 and 0.84%, respectively, of the t otal mercury added to the solution were volatilized. The optimum pH and tem perature for mercury volatilization were 2.5 and 30 degreesC. Approximately 92% of the total mercury in a salt solution (pH 2.5) with resting cells of SUG 2-2 (0.01 mg of protein), ferrous sulfate (3%) and mercury-polluted so il (1 g) was volatilized by further addition of both resting cells and Fe2 and by incubating for 30 d at 30 degreesC.