Abstract
Gaseous amines play an important role in atmospheric chemistry, affecting both climate and human health. They act as precursors to particles and break down to form potentially toxic products. Cattle husbandry have been established as one of the predominant atmospheric sources of gaseous amines, yet little is known about the emission rates of amines in this sector. To increase the basic knowledge in this field, monomethylamine, dimethylamine, and trimethylamine emissions were monitored during winter in a cattle barn at the Livestock Production Research Center of the Norwegian University of Life Sciences at Ås over a period of 46 days using a state-of-the-art mass spectrometer. The aim of this study was to determine amine volume mixing ratios in air and to determine amine emission rates. Trimethylamine (22 ± 11 mg h-1 animal-1) was found to be the most abundant methylamine emitted from the cattle barn, followed by monomethylamine (1.9 ± 0.9 mg h-1 animals-1) and dimethylamine (0.49 ± 0.17 mg h-1 animals-1). For comparison, the emission rate of ammonia was found to be 1.5 ± 0.6 g h-1 animal-1. To the best of my knowledge, this was the first study to determine monomethylamine and dimethylamine emission rates from cattle husbandry. Diurnal profiles and statistical analyses of the three methylamines versus the temperature suggested a temperature dependence of emissions, which was most apparent for monomethylamine. High levels of correlation between the three methylamines and ammonia indicated common sources, animal excrements being the most prominent candidate. However, laboratory measurements suggested silage food as an additional, minor source of trimethylamine.