Development of dynamic catchment scale microbial transport models

Large scale drinking water contamination events that have occurred in Canada in recent years, most notably the microbial contamination of a municipal system in Walkerton, ON, have demonstrated the need to develop an improved understanding of the fate and transport of microbial contaminants in the environment. The development of strategies for preventing the transmission of disease causing microorganisms in water systems requires specific knowledge with respect to pathogen sources, survival, and mobility. There are several knowledge gaps currently preventing the formulation of dynamic catchment scale microbial transport models. The mechanisms and factors which influence the extent to which microorganisms associate with sediment particles within the environment is one area which requires further research. The long-term goal of this research is to develop a physically based modeling system which can be used to predict microorganism transport within catchments dominated by diffuse pollution sources. The short-term objectives of the proposed research will focus on better understanding and representing sediment-microorganism interactions, and include: (i) quantify and compare the adsorption of bacterial, viral and protozoan indicator organisms to sediment particles within varying physiochemical environments, (ii) characterize the mechanisms by which microorganisms are transported from land surfaces to receiving water bodies, (iii) determine the size distribution of suspended sediments transported within rural catchments and characterize how microorganisms partition within these sediments, and (iv) develop and test equations to predict the transport of microorganisms on land surfaces and within surface waters. The proposed research will generate information and tools which will aid in identifying land-use strategies and structural controls which will prevent the migration of enteric microorganisms to surface waters.