In aquatic or subsurface environments, sulfate-reducing bacteria mediate the transformation of inorganic divalent mercury into highly toxic, bio-available methylmercury (MeHg), but it is unclear how this reaction depends on the phase of the Hg(ll). Zhang et al. examined the degree to which sulfate-reducing bacteria methylated three forms of Hg(ll), representing different size fractions and different states of aging: dissolved Hg(ll) ions, 3- to 4-nm-diameter HgS nanoparticles, and >500-nm HgS particles. The bacteria methylated dissolved Hg(ll) fastest, but there were also significant differences between nanoparticles and larger particles of HgS that were attributed to size-dependent crystallinity differences and not simply the amount of reactive surface area.
展开▼
