Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 27, 2011
Publication Date: August 15, 2011
Citation: Trabue, S.L., Scoggin, K.D., Mcconnell, L.L., Maghirang, R., Hatfield, J.L. 2011. Identifying and tracking key odorants from cattle feedlots. Atmospheric Environment. 45:4243-4251. Interpretive Summary: Odors are a significant emission from cattle feedlots that affect local communities air quality. There are a number of different compounds classes contributing to odor including amines, volatile fatty acids (VFAs), phenol compounds and indole compounds. At the source VFAs and phenol compounds were the dominant odorants, but downwind their importance diminishes and indole compounds become the dominate odorant. There is no single method to be used to quantify odor from agricultural sources. Future odor studies should focus on improving odor databases and understanding potential interactions between odorants to have greatest impact on predicting odors from animal production. Research results described in this report provides needed air quality information for growers, animal scientists, engineers, and regulatory officials on measuring odor from animal feeding operations.
Technical Abstract: Odors from cattle feedlots negatively affect air quality in local communities. The purpose of this study was to identifying key odorants using both analytical (odor activity values, OAV) and gas chromatrography GC-O (olfactometry) techniques, compare odor threshold databases, and track the movement of odors from source to receptor community. Odors emitted from a cattle feedlot were sampled onsite, 250m downwind and 3.2km downwind using both sorbent tubes and denuders. Sorbent tubes were analyzed by both GC/MS and GC/MS/O and key odorants determined using both OAV and GC-O, while denuders were analyzed by ion chromatography. Odor concentrations had a diurnal pattern with early morning and late evening being times of peak concentrations. Volatile fatty acids (VFA) were the most abundant of the major odorants. Odorants above their odor threshold at the feedlot included amines, VFAs, phenol compounds, and indole compounds. Key odorants at the feedlot were VFAs and phenol compounds, but their importance diminished with distance. Indole compounds while not the key odorant at the source increased in dominance downwind from the cattle feedlot. In general, the odorous compounds identified by GC-O and OAV were similar. GC-O was the more sensitive analytical technique and it identified several compounds that may have added to the unpleasantness of the cattle feedlot odor, but its through-put was extremely low limiting its usefulness. Improving field sampling devices and odor threshold concentration databases have the greatest potential to improve our understanding and confidence in evaluating odors.