Mercury Speciation in the Presence
of Polysulfides
Jenny Ayla Jay
François M. M. Morel
Harold F. Hemond
10.1021/es9911115.s001
https://acs.figshare.com/articles/journal_contribution/Mercury_Speciation_in_the_Presence_of_Polysulfides/3598737
Environmental mercury methylation appears modulated by
sulfide concentrations, possibly via changes in mercury
availability to sulfate reducing bacteria, the major agents
of this process in aquatic systems. Consequently, there has
been much recent interest in quantifying the chemical
speciation and lipid solubility of mercury in the presence
of sulfide and of polysulfides, which form by reaction of sulfide
with elemental sulfur or as intermediates in sulfur cycling.
We quantify a large increase in the solubility of cinnabar
(HgS<sub>(s)</sub>) in the presence of elemental sulfur, particularly at
high pH. Based on our data and those of Paquette and
Helz, we propose that the complex, Hg(S<i><sub>x</sub></i>)<sub>2</sub><sup>2-</sup>, dominates
the speciation of Hg(II) in such waters. At lower sulfide
concentrations and at high pH, the data are best fitted by
considering also the formation of the species HgS<i><sub>x</sub></i>OH<sup>-</sup>.
Octanol−water distribution (<i>D</i><sub>ow</sub>) experiments confirm the
charged nature of the dominant mercury−polysulfide
complexes and imply the presence of a minor lipophilic
polysulfide complex, such as HgS<sub>5</sub>. The recently reported
decrease in <i>D</i><sub>ow</sub> with increasing sulfide concentration
also occurs in the presence of polysulfides.
2000-04-21 00:00:00
presence
polysulfide
species HgS x OH
speciation
sulfide concentrations
D ow
Polysulfides Environmental mercury methylation
sulfur
pH
solubility
data