ABSTRACT
This chapter reviews the properties of the subsurface and the properties of microorganisms that influence their transport through geological material, their survival, and their capacity to degrade contaminants. Microorganisms to be effective in contaminant degradation, they must be transported to the zone of contamination, attach to the subsurface matrix, survive, grow, and maintain their degradative capabilities. Transport will depend upon complex interactions between the subsurface and the microorganism. Matrix properties that will affect transport include hydraulic conductivity, mineralogy, and sediment structure. Transport is greatly facilitated in water with low ionic strength. The concentration of microbial cells or spores may also affect the rate and extent of transport through subsurface materials. Inoculation or bioaugmentation has been widely used to stimulate bioremediation of subsurface material contaminated with petroleum hydrocarbons. Inoculation may be beneficial in the biodegradation of the high-molecular-weight polycyclic aromatic hydrocarbons, which are recalcitrant.
