Fate and Transport of Indicator Bacteria Bacteroidales in Surface Runoff From Agricultural Field.

The fate and transport of potential pathogenic bacteria in surface runoff from agricultural fields is of increasing environmental concern. Fecal contamination originated in agricultural activities, such as manure application to croplands, could greatly impact the safety of surface water if used as a drinking source and for other purposes. Order Bacteroidales are strict anaerobes and have been recently proposed as a sensitive indicator bacterium for detection of fecal contamination of natural water because they do not survive well under most environmental conditions. Several best management practices have been proposed to manage storm water runoff from agricultural fields as previous studies have suggested that the majority of contaminated runoff is associated with storm events. Riparian buffer zones, for example grass filter strips, placed between agricultural lands and waterways have been used for the purpose of reducing contaminants runoff associated with agricultural activities. However, it is often difficult to measure the buffer zone effect at the field scale level, and also little information is available concerning the transport of Bacteroidales through riparian buffer zones. We hypothesized there will be optimum conditions of grass filter strip slope and of manure application rate for reducing the risk of contaminated runoff from agricultural fields. To test our hypothesis, we conducted a study on field plots (16 m long and 2 m wide) where grass filter strips had been established on slopes of 2-6% and 6-12%. Different manure application rates were tested on each plot. Runoff which was simulating 60 m long contributing area with a 2% slope were applied and collected at the end of plots and analyzed for Bacteroidales concentrations. Results of this study will be presented.