Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2011
Publication Date: 9/1/2011
Citation: Trabue, S.L., Kerr, B.J., Bearson, B.L., Ziemer, C.J. 2011. Swine odor analyzed by odor panels and chemical techniques. Journal of Environmental Quality. 40:1510-1520. doi:10.2134/jeq2010.0522.
Interpretive Summary: Odor assessments from animal production facilities is challenging due to the nature of the compounds and limitations of sampling techniques. We determined that odor assessed by human panels is not recommended due to bias associated with sampling bags and great variability between different human panels. Chemical analysis of odors from animal production facilities needs to be assessed with caution primarily because of limitations associated with the odor sampling devices, analytical techniques and knowledge of odor threshold values for individual odor causing compounds. Future odor studies should focus on improving field sampling devices and odor threshold concentrations values since those areas have the greatest potential to improve our understanding and confidence in evaluating odors from animal production. The results described in this report provide information on measuring odor from swine operations that will be useful for growers, animal scientists, engineers, and regulatory officials.
Technical Abstract: The National Research Council identified odors as a significant animal emission at the local level, and highlighted the need for the development of standardized protocols for sampling and analysis. In this study, odorous air from swine manure was analyzed by both human panels and with analytical techniques. Odor analysis by human panels used dynamic dilution olfactometry (DDO), while chemical analysis used acid traps for ammonia, florescence for hydrogen sulfide (H2S), and thermal desorption (TDS) GC-MS for volatile organic compounds (VOC). In addition, GC-MS-O (olfactometry) was used for identifying key odorants. Odor was quantified for DDO using dilution thresholds, while chemical analysis used odor activity values (OAV). Odor samples analyzed by DDO were collected in 10 L Tedlar bags and analyzed within 24 hr using a dynamic dilution forced-choice olfactometer. The GC-O technique used for determining key odorants was GC-SNIFF. Odor results for DDO show there was significant differences between odor panels and considerable variability within odor panels for determining odor threshold values. Several key VOC odorants were lost or reduced in concentration by storage in Tedlar® bags, including both phenol and indole compounds. Only ammonia was significantly correlated to dilution thresholds. Chemical analysis showed that odor levels stabilized after Week 7 and H2S was the most dominate odor. Correlation of odorant concentration was closely associated with the origin of the odorant from the diet. Other key odorants determined by both chemical and GC-MS-O included indole compounds, phenol compounds, ammonia, and several volatile fatty acids (i.e., butanoic, 3-methylbutanoic, and pentanoic acids).