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| Submitter's Name |
Kathleen Vazquez |
| Session Name |
Poster Session - Agricultural/Silvicultural Water |
| Poster Number |
13 |
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| Author(s) |
Kathleen Vazquez, Department of Agricultural and Biological Engineering, University of Florida (Presenting Author) |
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Arie Havelaar,
Emerging Pathogens Institute, Institute for Sustainable Food Systems, Department of Animal Sciences, University of Florida |
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Rafael Muñoz-Carpena, Department of Agricultural and Biological Engineering, University of Florida |
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A Mechanistic Bacterial Transport Model to Inform Food Safety Management of Agricultural Pond Water |
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Irrigation water is considered a major pathway to fresh produce for food-borne illness related pathogens. The Food Safety Modernization Act (FSMA) specifies sampling-based methods using Escherichia coli as an indicator organism and microbial criteria, geometric mean (GM) and statistical threshold value (STV), to regulate agricultural water. These regulations lack preventive measures, important to controlling the processes that introduce bacterial contamination into water sources. To inform FSMA regulations concerning agricultural water, this study develops a simple mechanistic model to predict the microbial quality of agricultural water. This model proved useful to simulate data from a highly variable surface water irrigation pond in West Central Florida. The performance of the model was similar or superior to existing pathogen transport models, with a Nash-Sutcliffe efficiency of 0.574 when incorporating observed values uncertainty. Global sensitivity analysis is then used to reveal the most important processes controlling bacterial water quality criteria: aquatic removal rate of bacteria for GM, and bacterial source and transport dynamics STV. It was also found that large peaks E. coli concentration events were mechanistically driven by rainfall/runoff processes. From these findings, we suggest preventative measures enhancing die-off rates through treatment after large runoff-producing rainfall events. Bacterial source characteristics such as wildlife population should be controlled in instances where STV exceeds regulatory limits. Vegetative filter strips, when properly designed and maintained, also provide an opportunity to mitigate bacterial transfer into the agricultural waters by reducing runoff flow and settling particulated pollutants. |
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