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Abstract

We studied the atmospheric aerosol of a farm directly on farm, downwind, and in the background with the aim to characterize the aerosol source of livestock farming physically and chemically. The farm hosted chicken, cattle and pig. The farm was found to be a source of primary and secondary particles. Super-mum particles of various types were emitted from the stables and adjacent facilities related to farming activities. On farm elevated concentrations of ammonia, particulate ammonium and nitrate were observed. The significant emission of condensation nuclei and large, 2 mum-sized particles ( droplets) was observed under humid conditions in plumes which most likely originated from open manure pits at least in one case. It is suggested that this aerosol mode consisted of ammonium haze droplets formed by saturation of advected air with ammonia within a few minutes. In one night, a mass uptake of Delta m >5.4 mug m(-3) in the super-mum mode was observed along with a loss of Deltam = -1.0 mug m(-3) in the sub-mum mode based on differential sampling upwind and downwind of the farm. The particulate matter mass median diameter was correspondingly shifted from 1.32 to 3.39 mum. About one third of the mass increase was due to organic carbon. Furthermore, differential sampling showed particulate calcium and nitrate/nitric acid to be emitted from the farm, too. The study encourages to systematically characterize the aerosol emitted from livestock raising in future studies of similar kind