| Abstract
| - To investigate the transport and fate of fecal pollution atGreat Lakes beaches and the health risks associated withswimming, the near-shore waters of Lake Michigan andtwo tributaries discharging into it were examined for bacterialindicators of human fecal pollution. The enterococcushuman fecal pollution marker, which targets a putativevirulence factorthe enterococcal surface protein (esp)in Enterococcus faecium, was detected in 2/28 samples (7%)in the tributaries draining into Lake Michigan and in 6/30samples (20%) in Lake Michigan beaches. This was indicativeof human fecal pollution being transported in the tributariesand occurrence at Lake Michigan beaches. To understandthe relative importance of different processes influencingpollution transport and inactivation, a finite-elementmodel of surf-zone hydrodynamics (coupled with modelsfor temperature, E. coli and enterococci) was used.Enterococci appear to survive longer than E. coli, whichwas described using an overall first-order inactivationcoefficient in the range 0.5−2.0 per day. Our analysis suggeststhat the majority of fecal indicator bacteria variation canbe explained based on loadings from the tributaries. Sunlightis a major contributor to inactivation in the surf-zoneand the formulation based on sunlight, temperature andsedimentation is preferred over the first-order inactivationformulation.
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