Analysis of ammonia, ammonium aerosols and acid gases in the atmosphere at a commercial hog farm in eastern North Carolina, USA

Measurements of atmospheric ammonia, acid gases, and ammonium aerosols were made at a commercial hog farm in Eastern North Carolina, USA, during September through December of 1997. Annular denuder systems (ADS) were used to sample gaseous (hydrogen chloride, nitrous acid, nitric acid, sulfur dioxide and ammonia) and fine aerosol (ammonium, chloride, nitrate, and sulfate) species. Ammonia and ammonium concentrations were determined by colorimetric analysis of the sample extracts. The acid gases and remaining fine particle ionic species were determined by ion chromatographic analysis of the sample extracts. Mean concentrations of the gaseous hydrogen chloride, nitrous acid, nitric acid, sulfur dioxide and ammonia were 0.743 μg/m3, 0.255 μg/m3, 0.154 μg/m3, 2.968 μg/m3, and 10.48 μg/m3, respectively. Mean concentrations of the fine particle chloride, nitrate, sulfate and ammonium were 0.321 μg/m3, 0.548 μg/m3, 3.247 μg/m3, and 1.102 μg/m3, respectively. The fine aerosol fraction was dominated by ammonium sulfate particles. A linear regression of sulfate versus ammonium by equivalent concentration showed a slope of 0.715 and r2 of 0.88. An emission factor for total ammonia nitrogen flux was estimated using a simple box model as approximately 5 to 10 kg animal−1 year−1.