New insights into concentrations, sources and transformations of NH3, NOx, SO2 and PM at a commercial manure-belt layer house.

Pollutant gases and particulate matters (PM) from livestock facilities can affect the health of animals and farm workers and lead to great social environmental risks. This paper presents a comprehensive study on the characteristics of ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2) and PM (including PM2.5 and PM10) in a 100,000-bird manure-belt layer house in suburb Beijing for three typical seasons of summer, autumn and winter. Indoor air was sampled at an exhaust fan of the mechanically ventilated commercial house. The monitored indoor concentrations of NH3, NOx, SO2, PM2.5 and PM10 were 3.7-5.0 mg m-3, 17-58 μg m-3, 0-11 μg m-3, 100-149 μg m-3 and 354-828 μg m-3, respectively. The indoor NH3 concentrations were largely influenced by the manure removal frequency. The NOx and SO2 were mainly sourced from the ambient air, and the NOx was also partly sourced from manure decomposition in summer. The indoor PM2.5 and PM10 were largely sourced from the ambient air and the indoor manure, respectively. The abundant indoor NH3 caused significantly higher NH4+ concentration in the indoor PM10 (7.98 ± 9.04 μg m-3) than that in the ambient PM10 (3.48 ± 3.52 μg m-3). Secondary inorganic ions (SO42-, NO3- and NH4+) totally contributed 5.7% and 14.6% to the indoor and ambient PM2.5, respectively; they contributed 2.8% and 8.9% to the indoor and ambient PM10, respectively. Organic carbon was the main component of the PM and accounted for 26.6% and 41.5% of the indoor PM2.5 and PM10, respectively. Heavy metal elements (Zn, Cu and Cr) were likely transported from feed to manure and finally accumulated in the PM. Given the high emission potential, the air pollutants from animal production suggested potential risks for human health.