Characterization and Quantification of Emissions from Dairy CAFO's

Abstract

Animal agriculture is a major source of atmospheric pollutants, but the nature and dispersion of those pollutants are not well understood. Additionally, little data is available on the vertical profile of emissions since few studies have looked at emissions above 10 m. The aim of this study was to quantify emissions of ammonia, ammonium, nitric acid, methane, carbon dioxide, and nitrous oxide from dairy systems, and characterize the spatial, and seasonal variability of those emissions. Using a unique mobile sampling methodology employing helium balloons, filter packs, syringe pumps and a tethersonde meteorological sampling system, gases and particulates were measured at five heights at three locations downwind and one location upwind of two dairies. This innovative technique provided a spatially resolved characterization of the emission plume. Measurements were made seasonally at two dairies from 2005 to 2006. Results show that the concentration of each species varied vertically and seasonally, and that each dairy had its own distinct profiles. Seasonally, the greenhouse gases had maximum concentrations in the winter months, while ammonia was highest in the summer. Despite differences between the two diaries, maximum concentrations were commonly found at or near ground level (2 m) indicating a strong emission source from the dairy. Above 2 m, ammonia exhibited the most consistent vertical profile, which steadily decreased with height (P = 0.04) up to 35 m. This study characterized the seasonal and spatial variability of emissions from two dairy operations, which are important considerations when measuring and modeling gaseous emissions for scientific or regulatory purposes.