Modeling the Fate and Transport of Bacteriophage PRD-1 in a Large Surface Water System: The Grand River Watershed, Michigan

Understanding the transport of biological agents that mimic the movement of pathogenic microorganisms in surface waters is important from the point of human health as well as risk assessment. In May 2006, we conducted a field experiment on the Grand River, Michigan using a conservative tracer (Rhodamine-WT) and the bacteriophage PRD-1, a surrogate for human viruses. Observed concentrations of the chemical and biological tracers were described using a transport model that included the effects of transient storage in addition to virus sorption and inactivation. Linkages between watershed-scale processes and in-stream processes were an important aspect of the modeling. Here we describe the similarities and differences between the two tracers (e.g., travel times and recovery factors) as well as environmental factors that influence virus transport and inactivation in the surface water system.