water could also stimulate methylation and limit photodegradation of MeHg and photoreduction of ionic Hg.Furthermore, wetlands support sulfate-reducing bacteria,which appear to be largely responsible for Hg methylation(Benoit et al. 2003). Concentrations of MeHg in wetland
porewaters (waters filling the spaces between solid material in sedimentary deposits) and surface waters vary seasonally,with the highest concentrations evident during the late summer, presumably as a result of warmer temperatures, higher rates of microbial activity, and longer hydraulic residence times (Galloway and Branfireun 2004).