The transport of viruses in groundwater was studied by using two bacteriophages (PRD-1 and M-1) and carboxylated latex microspheres (100 nm) under forced gradient conditions. This study was also designed to determine the effects of a change in pH of the aquifer on the transport of viruses and microspheres, and if the microspheres reflected the transport of viruses. The microspheres, bacteriophage, and chloride tracers were injected for a period of 12 hours into a fine- to medium-sand aquifer, 9 to 10 m in depth underlayed by a clay silt bed. Samples were collected 1, 2.5, 4, and 6 m distant from the injection well. After 10 days the pH of the groundwater was increased from 7.5 to 8.5 and samples collected for an additional 7 days. The results of this study indicated that a small increase in the pH of an aquifer can cause detachment of viruses and microspheres from the soil. In addition, the transport behavior of the bacteriophage was found to be different from the carboxylated microspheres.hydrology collectio
