Volatile organic compound emission and other trace gases from selected animal buildings

Using chemical ionization mass spectrometry and photoacoustic spectroscopy, we analysed the evolution of volatile organic compounds (VOCs) and other trace gases during an approximately one-week measurement period each in a pigsty and a sheep shed at the Federal Agricultural Research Centre (FAL) in Mariensee, Germany. When activities in the sheep shed were most intense during feeding hours and manure removal, concentration surges of VOCs were observed, which strongly correlated with methane and ammonia levels. Immediately after this disturbance, especially the manure removal, which lasted for about 30 minutes, the short-term concentration spikes decayed exponentially as a result of dilution of the shed air with relatively clean air from outside the shed. Emission factors were modelled from the daily surge and decay profiles in the shed and were further used to estimate emission rates for Germany. Concentrations measured at an exhaust flue of a pigsty section were much smoother than in the sheep shed. For both sheds, correlations of VOC mixing ratios with methane or ammonia were used to calculate shed, respectively per animal emission factors, and to estimate nationwide release rates for a number of VOCs. VOC emissions from both sheds were dominated by alcohols, ethanol from the sheep, methanol from the pigs. Ethanol and other fermentation products have known sources in the fodder and the excrements. New is the finding that also high amounts of methanol are released, the source of which is not entirely clear. Total annual VOC emissions from the animal husbandry sector in Germany are likely around 150 Tg carbon, less than previously estimated and of a much different composition.