Continuous Measurement of Ammonia at an Intensive Pig Farm in Wuhan, China

Abstract

Measurements with high time resolution are necessary to capture variation patterns and to facilitate the estimation of uncertainty in ammonia inventories. Continuous real-time monitoring of ammonia was carried out in a naturally ventilated nursery pig house during two periods in winter and summer, respectively. A higher ventilation rate of about 73,799 ± 39,655 m3/h was obtained during the summer period in comparison with 1646 ± 604 m3/h in the winter. Correspondingly, ammonia level observed in summer (0.25 ± 0.10 mg/m3) was lower than that in winter (1.28 ± 0.74 mg/m3). Spatial variation of ammonia concentration was observed during the winter monitoring period. The mean ammonia emission factor was about 0.3221 ± 0.2921 g d−1 pig−1 in summer and 0.1039 ± 0.0550 g d−1 pig−1 in winter, ranging from 0.0094 to 1.9422 g d−1 pig−1 and 0.0046 to 0.2899 g d−1 pig−1, respectively. Significant correlation was found between ammonia emission and indoor temperature and relative humidity during the winter period. For the summer measurement, effects of ventilation rate and ammonia concentration on ammonia emission were significant. Prominent diurnal pattern existed for both ammonia concentration and emission, with higher emission rates during daytime. The results confirmed the existence of considerable uncertainty associated with the ammonia emission factor, acquired by snapshot measurements.