Inhibition of mercury methylation in anoxic freshwater sediment by group VI anions
- Univ. of Nevada, Reno, NV (United States). Dept. of Environmental and Resource Sciences
- Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Geology
The addition of group VI anions to sediment slurries resulted in the inhibition of the rate of mercury (Hg) methylation. The ranking of inhibition is as follows: tellurate (TeO{sub 4}{sup 2{minus}}) > selenate (SeO{sub 4}{sup 2{minus}}) > molybdate (MoO{sub 4}{sup 2{minus}}) > tungstate (WO{sub 4}{sup 2{minus}}). In sediment slurries treated with TeO{sub 4}{sup 2{minus}} and Se{sub 4}{sup 2{minus}}, methylmercury (MeHg) formation was significantly inhibited (p < 0.05) at the concentrations >50 nM of TeO{sub 4}{sup 2{minus}} and >270 nM of SeO{sub 4}{sup 2{minus}}, while the significant inhibition (p < 0.05) of Hg-methylation by MoO{sub 4}{sup 2{minus}} and WO{sub 4}{sup 2{minus}} was observed in slurries spiked at final concentrations {le}100 {micro}M and {le}700 {micro}M, respectively. Increasing the sulfate (SO{sub 4}{sup 2{minus}}) concentration while using fixed concentrations of inhibitors led to the partial reestablishment of some MeHg production in WO{sub 4}{sup 2{minus}}-treated slurries, whereas, no such significant change was noticed in sediment slurries treated with MoO{sub 4}{sup 2{minus}} and TeO{sub 4}{sup 2{minus}}. These observations suggested that WO{sub 4}{sup 2{minus}} inhibits Hg methylation by a competitive mechanism, while MoO{sub 4}{sup 2{minus}} and TeO{sub 4}{sup 2{minus}} are noncompetitive inhibitors. Selenate and SO{sub 4}{sup 2{minus}} showed a qualitatively similar effect on Hg methylation at concentrations tested, in that each showed stimulation at low concentrations and inhibition at high concentrations. The depression of MeHg formation by group VI anions was not accompanied by an inhibition of general microbial activity, suggesting that only particular microorganisms, such as sulfate-reducing bacteria, are responsible for Hg methylation.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States)
- OSTI ID:
- 538154
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 16, Issue 8; Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Inhibition of mercury methylation in anoxic freshwater sediment by Group VI anions
Reduction of SeO{sub 4}{sup 2{minus}} anions and anoxic formation of iron(II)-Iron(III) hydroxy-selenate green rust