Abstract
AbstractThe 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) > selenate (TeO) > molybdate (MoO) > tungstate (WO). In sediment slurries treated with TeO and SeO, methylmercury (MeHg) formation was significantly inhibited (p < 0.05) at the concentrations >50 nM of TeO and >270 nM of SeO, while the significant inhibition (p < 0.05) of Hg‐methylation by MoO and WO was observed in slurries spiked at final concentrations ≥100 μM and ≥700 μM, respectively. Increasing the sulfate (SO) concentration while using fixed concentrations of inhibitors led to the partial reestablishment of some MeHg production in WO‐treated slurries, whereas, no such significant change was noticed in sediment slurries treated with MoO and TeO. These observations suggested that WO inhibits Hg methylation by a competitive mechanism, while MoO and TeO are noncompetitive inhibitors. Selenate and SO 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. Finally, in the concentration ranges encountered in most natural aquatic environments, the inhibition of MeHg production by group VI anions is unlikely, except in systems where those elements are found in anomalously high concentrations.
Published Version
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