Simultaneous Determination of Gaseous Ammonia and Particulate Ammonium in Ambient Air Using a Cylindrical Wet Effluent Diffusion Denuder and a Continuous Aerosol Sampler

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

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.

Impact of manure compost amendments on NH3 volatilization in rice paddy ecosystems during cultivation

Livestock manure has been widely used in agriculture to improve soil productivity and quality. However, intensive application can significantly enhance soil nitrogen (N) availability and facilitate ammonia (NH₃) volatilization during rice cultivation. The effects of different rates of manure application on the NH₃ volatilization rate, its mechanism, and their relationships have not been comprehensively investigated. In this study, field trials were conducted to investigate NH₃ volatilization in rice paddy soils amended with different livestock manure, cattle manure (CM), and swine manure (SM), at a rate of 0 (NPK), 10, 20, and 40 Mg ha^-1 during cultivation. Moreover, the soil physicochemical and biological properties and rice N uptake were investigated. Ultra-fine particulate matter (PM_2.5) was measured quantitatively and qualitatively. Manure application significantly increased NH₃ emissions compared to the control. Much higher volatilization rates were observed in the SM soils than in the CM soils, even when the same amount of N was applied. This is mainly related to the higher labile NH₄⁺ concentration and urease activity in SM soils. With increasing application levels, NH₃ emission rates proportionally increased in the SM, but there was no significant difference in the CM. Livestock manure application significantly increased NH₃ volatilization, particularly during the initial manure application and additional fertilization stages during rice cultivation. The results showed that the application of livestock manure significantly increased NH₃ volatilization. Moreover, the biochemical properties of manure composts, including labile N and urease activity, mainly affected NH₃ dynamics in rice paddies during cultivation rather than their type. Irrespective of manure application, PM_2.5, did not show a significant difference at the initial stage of cultivation. NH₃ volatilization was not significantly correlated with the formation of PM_2.5. It is necessary to develop effective strategies for mitigating NH₃ volatilization and maintaining soil quality without decreasing rice productivity in paddy ecosystems.