Pathogens: Health relevance, transport and attenuation

This chapter will summarize current knowledge about the distribution of pathogens in groundwater and the factors that control their transport and attenuation. The aim is to provide a level of information and interpretation that will allow public health specialists and water resource managers to estimate risks to the groundwater from microbial contaminants derived from sources described in Section II of this monograph, for example, agricultural and urban sources. Many factors, some environmental and others linked to the properties of the organism, control the survival and transport of microorganisms in the subsurface. However, it is important to consider that often the factors perceived to be of importance have been studied in isolation using controlled laboratory experiments and the conclusions then extrapolated to predict the fate of pathogens in the environment. This process is known as upscaling and is itself the subject of current research. In contrast, very few studies have attempted to examine the effect of multiple factors interacting in the natural environment. Current knowledge therefore offers a number of guiding principles about the transport and attenuation of pathogens in groundwater, but th