Fate and Transport of Pathogens in the Subsurface

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Pathogenic bacteria and viruses represent significant health threats to water supplies in Canada (CCME, 2010) and around the world (WHO, 2006). Pathogens can enter the subsurface from septic systems, agricultural activities, sludge disposal, and infiltration of contaminated runoff. In most cases, pathogens travel through the near surface unsaturated zone, to the saturated zone. Subsequent transport to water supply wells can lead to serious impacts on human health. Transport of bacteria and viruses through the subsurface is a complex process, influenced by the physicochemical nature of the bacteria and viruses and of the subsurface environment. In spite of decades of study, transport of bacteria and viruses in the subsurface, particularly in the unsaturated zone, and in fractured rock and clay is not well understood. Laboratory studies will be conducted to improve the understanding of the fate and transport of bacteria and viruses in the subsurface, including the unsaturated zone, and fractured rock and clay. A variety of surrogates for pathogenic bacteria and viruses will be used in the studies. The effects of pathogen characteristics, soil properties, geochemistry, and biofilms will be examined using pore scale, and one and two dimensional bench scale systems in combination with atomic force microscopy and quartz crystal microbalance studies. New mechanistic models for predicting the fate and transport of bacteria and viruses in porous and fractured media will be developed. These models will include a microscale model Lattice Boltzmann flow model with biofilm growth and pathogen transport. Field scale models will be developed that incorporate the results of experimental studies and microscale modelling. The results of this research can be used by Canadian regulators and risk assessors in developing comprehensive policies for protection of subsurface water resources from contamination by pathogens. leading to improved protection of the health of the Canadian public.The project will provide excellent opportunities for training the 3 Ph.D. and 3 M.A.Sc. students in an interdisciplinary environment involving hydrogeology, microbiology, colloidal chemistry and geochemistry, in state of the art laboratory and computational facilities.