2007 Volume 116 Issue 6 Pages 915-921
Microorganisms have a variety of functions that relates to the remediation of subsurface contaminants. Therefore, they are important in subsurface environments. Studies on subsurface microbial ecology with the aim of remediating subsurface contamination have mainly focused on groundwater or aquifer materials because the aquitard (composed of clay or silt) has been considered as a place with little or no microbial activity. However, recent studies on microbiology in aquitard materials have revealed new aspects of this environment. The aquitard can be a source of nutrients, such as organic matter, to the adjacent aquifer, and stimulate microbial activity in the aquifer. Microbial activity is considered to be limited by the pore size distribution of the aquitard, and relatively higher microbial activity has been detected in a younger and shallower aquitard with larger pore size. In this article, I introduce these relationships between subsurface microorganisms and the aquitard.