Tuesday, October 23, 2007 : 2:30 p.m.
Influence of Redox Conditions on Pharmaceutical Transport in Ground Water
Elevated concentrations of pharmaceutical compounds occur in ground water as the result of releases from a number of sources, including wastewater and solid-waste disposal facilities. A combination of physical, chemical and microbiological processes controls the transport, persistence, and eventual fate of these compounds in the subsurface. A series of field studies was conducted at three septic system sites and a municipal landfill site in Ontario, Canada, to evaluate the influence of aquifer properties and geochemical conditions on pharmaceutical transport. Ground water was sampled from networks of piezometers installed in the vicinity of these contaminant sources and analyzed for a suite of 14 common pharmaceutical compounds, and pH, redox potential, concentrations of major ions, and redox sensitive species. The study showed marked site-to-site differences in pharmaceutical transport and highly variable transport within a given site. Although the variations in transport can be explained, in part, by differences in compound partitioning coefficients, variations in wastewater infiltration rates and redox conditions seem to provide a greater control on compound transport from the disposal areas. Several compounds were observed to be persistent in reducing parts of the plumes, and less persistent under aerobic conditions. Others were persistent over a broader range of geochemical conditions. This data suggests a number of factors influenced the transport of the pharmaceuticals from the waste sites, including solid-phase properties, aqueous geochemistry, residence time in the unsaturated zone, and ground water velocity.
Carol J. Ptacek, Ph.D., University of Waterloo Dr. Carol Ptacek is a Professor in the Department of Earth Sciences of the University of Waterloo since 2006. Prior to joining the University of Waterloo full-time, she was employed for 14 years as a Research Scientist and subsequently Section Head for Groundwater Remediation at the National Water Research Institute, Environment Canada. She received M.Sc. and Ph.D. degrees in Contaminant Hydrogeology and Geochemistry from the University of Waterloo. She conducts research on the fate and remediation of metals, nutrients and emerging contaminants in ground water.
6th International Conference on Pharmaceuticals and Enocrine Disrupting Chemicals in Water