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Estimation of decay rates for fecal indicator bacteria and bacterial pathogens in agricultural field-applied manure
Field-applied manure is an important source of pathogenic exposure in surface water bodies for humans and ecological receptors. We analyzed the persistence and decay of fecal indicator bacteria and bacterial pathogens from three sources (cattle, poultry, swine) for agricultural field data collected in Watkinsville, Georgia. Data from a completely randomized split-plot design was generated by collecting runoff from rainfall simulation experiments on small manure-applied field plots and a control over a three week period. A one-stage exponential decay model was used to estimate decay coefficients and half-lives for 17 different pathogens for four different sampling periods. We present seasonal estimations of decay rates for fecal bacteria and compare these values to similar studies from the literature. Although a number of bacteria were not analytically recoverable, others (e.g. Campylobacter, Clostridium, Cryptosporidium, E. coli, Enterococci, Giarida, Salmonella) had seasonal estimates of decay with half-lives that ranging from one day to two weeks. We examine the strength of the correlation between fecal indicator bacteria and pathogen decay rates and examine the influence of seasonal influences (temperature, sunlight, moisture content) and manure source.
Presentation given at the Annual Meeting of the Association of Southeastern Biologists, April 4 - 7, 2012 in Athens, GA.
Record Details:Record Type: DOCUMENT (PRESENTATION/POSTER)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LAB
ECOSYSTEMS RESEARCH DIVISION