Major ionic compositions of fine particulate matter in an animal feeding operation facility and its vicinity

Abstract

Animal feeding operations (AFOs) produce particulate matter (PM) and gaseous pollutants. Investigation of the chemical composition of PM2.5 inside and in the local vicinity of AFOs can help to understand the impact of the AFO emissions on ambient secondary PM formation. This study was conducted on a commercial egg production farm in North Carolina. Samples of PM2.5 were collected from five stations, with one located in an egg production house and the other four located in the vicinity of the farm along four wind directions. The major ions of NH4+, Na+, K+, SO42−, Cl−, and NO3− were analyzed using ion chromatography (IC). In the house, the mostly abundant ions were SO42−, Cl−, and K+. At ambient stations, SO42−, and NH4+ were the two most abundant ions. In the house, NH4+, SO42−, and NO3− accounted for only 10% of the PM2.5 mass; at ambient locations, NH4+, SO42−, and NO3− accounted for 36–41% of the PM2.5 mass. In the house, NH4+ had small seasonal variations indicating that gas-phase NH3 was not the only major force driving its gas–particle partitioning. At the ambient stations, NH4+ had the highest concentrations in summer. In the house, K+, Na+, and Cl− were highly correlated with each other. In ambient locations, SO42− and NH4+ had a strong correlation, whereas in the house, SO42− and NH4+ had a very weak correlation. Ambient temperature and solar radiation were positively correlated with NH4+ and SO42−. This study suggests that secondary PM formation inside the animal house was not an important source of PM2.5. In the vicinity, NH3 emissions had greater impact on PM2.5 formation.ImplicationsThe chemical composition of PM2.5 inside and in the local vicinity of AFOs showed the impact of the AFO emissions on ambient secondary PM2.5 formation, and the fate and transport of air pollutants associated with AFOs. The results may help to manage in-house animal facility air quality, and to develop regional air quality control strategies and policies, especially in animal agriculture-concentrated areas.