P1-07 Evaluation of Bioaerosol Dispersal and Deposition Relative to Setback Distances between Manure Sources and Fresh Produce Crops

Monday, August 1, 2016
America's Center - St. Louis
Patricia Millner, U.S. Department of Agriculture ARS EMFSL, Beltsville, MD
Fawzy Hashem, University of Maryland Eastern Shore, Princess Anne, MD
Tong (Nancy) Liu, University of Maryland, College Park, MD
Brett Smith, University of Maryland Eastern Shore, Princess Anne, MD
Chanelle White, University of Maryland Eastern Shore, Princess Anne, MD
Andrea Bolling, University of Maryland Eastern Shore, Princess Anne, MD
Introduction: Animal rearing and manure handling facilities are considered possible sources of human pathogens that may aerosolize and deposit onto nearby fresh produce, thereby increasing foodborne illness risk potential of the impacted commodities. Highly variable meteorological, landscape, and farm conditions make prediction of set-back buffer distances from farm animal and manure handling sources exceptionally challenging.

Purpose: The objective was to evaluate the influence of a range of on-site conditions on bioaerosol concentrations, transport, and deposition, and then use dispersion models to determine set-back distances between fresh produce operations and farm manure sources of fecal bacteria.

Methods: Several field experiments were conducted during typical animal rearing/manure handling operations. Bioaerosols from poultry house ventilation exhaust and during poultry litter and dairy manure handling and composting operations were collected 3-182 m downwind using Anderson impactors, SpinCon cyclonic air samplers, and open-face filters. Deposition was determined using tomato, lettuce, spinach, and basil plants and sterile water basins. Total aerobic bacteria, fecal coliform and E. coli concentrations were determined by conventional plating and MPN procedures (n=300 samples). Emission rates were derived and used to model airborne concentrations and deposition at various distances downwind of the sources under a range of meteorological and landscape conditions.

Results: Source strength, manure handling and moisture content, along with meteorological conditions, downwind distance, and vegetative buffer belts impacted the concentrations of viable airborne target bacteria and their downwind deposition onto plants and water surfaces. The complexity of multiple interacting factors makes atmospheric dispersion and deposition modeling essential methods to predict the likelihood of produce contamination events and the most conducive conditions.

Significance: Determining reasonable setback distances from suspected sources of zoonotic pathogens in order to protect nearby fresh produce crops from contamination via bioaerosol deposition will benefit from consideration of site-specific factors and use of atmospheric dispersion models.