VOC Concentrations Downwind of Beef Feedlots during Intense Odour Events
A growing number of livestock feeding operations, together with expanding cities and increasing rural residential populations in many states in the United States, are creating issues of maintaining operational capabilities while satisfying public expectations of environmental quality. Given the economic importance of the cattle feeding industry, especially in Texas, it is essential that we develop a better understanding of odor, odor transport, and odor persistence from beef cattle feedyards. In this research, ambient concentrations of volatile organic compounds (VOCs) were measured upwind, onsite, and up to 8 km downwind of two beef cattle feedyards using thermal desorption tubes and gas chromatography/mass spectrometry. Samples were collected downwind of pens, wastewater storage ponds, and feed sources. Concurrently, odor was characterized by human panelists both on-site during sampling and in the lab using Tedlar bags and triangular forced-choice olfactometry. Odor data was compared with chemical concentrations to obtain a greater understanding of the persistence of individual odorants with regard to both the odorous compounds present and detection ability of the population. Odor samples collected downwind of the pens had the greatest concentrations of p-cresol, one of the most significant odorous chemicals downwind of feedyards. Downwind chemical concentrations peaked at the property line and were significantly reduced at 1 km from the feedyard boundary.