Identification and quantification of volatile organic compounds from a dairy

Volatile organic compounds (VOCs) that contribute to odor and air quality problems have been identified from the Washington State University Knott Dairy Farm using gas chromatography–mass spectroscopy (GC–MS). Eighty-two VOCs were identified at a lactating cow open stall and 73 were detected from a slurry wastewater lagoon. These compounds included alcohols, aldehydes, ketones, esters, ethers, aromatic hydrocarbons, halogenated hydrocarbons, terpenes, other hydrocarbons, amines, other nitrogen containing compounds, and sulfur-containing compounds. The concentration of VOCs directly associated with cattle waste increased with ambient air temperature, with the highest concentrations present during the summer months. Concentrations of most detected compounds were below published odor detection thresholds. Emission rates of ethanol (1026±513 μg cow−1 s−1) and dimethyl sulfide (DMS) (13.8±10.3 μg cow−1 s−1) were measured from the lactating stall area using an atmospheric tracer method and concentrations were plotted using data over a 2-year period. Emission rates of acetone (3.03±0.85 ng cow−1 s−1), 2-butanone (145±35 ng cow−1 s−1), methyl isobutyl ketone (3.46±1.11 ng cow−1 s−1), 2-methyl-3-pentanone (25.1±8.0 ng cow−1 s−1), DMS (2.19±0.92 ng cow−1 s−1), and dimethyl disulfide (DMDS) (16.1±3.9 ng cow−1 s−1) were measured from the slurry waste lagoon using a laboratory emission chamber.