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Fecal Indicator Bacteria and Environmental Observations: Validation of Virtual Beach
Citation:
WHITE, E. M., R. G. ZEPP, M. MOLINA, K. L. WOLFE, AND W. E. FRICK. Fecal Indicator Bacteria and Environmental Observations: Validation of Virtual Beach. Presented at Gordon Research Conference on Oceans & Human Health, Tilton, NH, June 29 - July 04, 2008.
Impact/Purpose:
These modeling studies include efforts to develop and test dynamic predictive models for nowcasting bacterial levels at beaches based on short-term data sets. Current predictive models are based mainly on data that require years to obtain. The Virtual Plumes software is being used to enhance Virtual Beach at sites where a point source input of fecal contaminants from POTWs are a major source.
Description:
Contamination of recreational waters by fecal material is often assessed using indicator bacteria such as enterococci. Enumeration based on culturing methods can take up to 48 hours to complete, limiting the accuracy of water quality evaluations. Molecular microbial techniques employing the quantitative polymerase chain reaction (qPCR) show great promise due to shorter reporting times. However, decision makers need additional tools to predict pathogen exposure and identify sources of contamination at beaches. We are currently conducting studies at several beach sites to validate the empirical modeling component of the Virtual Beach software. This modeling tool has been developed to provide beach managers with early warnings of bacterial levels that pose health risks. Bacterial concentrations can be highly dynamic in response to a number of environmental factors including meteorological conditions, hydrodynamics, solar irradiance, and water chemistry. Current studies involve concurrent measurements of microbial levels and environmental observations at the beaches. The data will be used with the Virtual Beach software to develop statistical models that nowcast and forecast microbial levels. Preliminary findings will be presented. Laboratory studies investigating the role of ultraviolet (UV) radiation on the fate of culturable and qPCR-determined enterococci will also be reported, including the effects of chromophoric dissolved organic matter (CDOM) and suspended sediments. Results indicate that the sensitivity of enterococci DNA and whole cells to UV radiation may be very different.