Ammonia emissions of an open-lot dairy in North China Plain: Field experiments and source inversion

Significant uncertainties exist in China's ammonia emission inventories, particularly in livestock husbandry. Three phases of field experiments were conducted in summer and winter in an open-lot dairy to estimate ammonia emissions. The dairy is located in the northwest suburb of Beijing (40 degrees 9 & PRIME;47.88 & DPRIME;N, 116 degrees 17 & PRIME;1.63 & DPRIME;E, 47 m a.s.l.) with about 400 cows, a representative condition in North China Plain. The exploratory phase lasted from May 29 to July 18, 2016; the intensive phases lasted from December 16, 2016, to January 10, 2017, and from June 1 to July 2, 2018. Ammonia concentrations were measured upwind and downwind of the dairy, along with wind statistics. After quality control, the data were used to determine the contribution of the prescribed source areas to the measured ammonia concentrations using an analytical footprint model. Therefore, the source intensity was inversely derived under the assumption that the emission rate was spatially homogeneous over the source areas. Diurnal variation of ammonia emission from the dairy was revealed, with peaks around noon being 0.66 g s -1 in winter and 0.80 g s -1 in summer. The total emissions of the dairy are 0.38 & PLUSMN; 0.13 g s -1 in winter and 0.46 & PLUSMN; 0.10 g s -1 in summer, corresponding to the emission factors 82 & PLUSMN; 27 g head-1 d -1 in winter and 99 & PLUSMN; 23 g head-1 d -1 in summer. The results were comparable to previous studies using similar methods and to those in China's ammonia source inventory.

Automated summary

Significant uncertainties exist in China's ammonia emission inventories, particularly in livestock husbandry. Three phases of field experiments were conducted in an open-lot dairy to estimate ammonia emissions. The results showed diurnal variations in ammonia emissions from the dairy, with winter peaks around 0.66 g/s and summer peaks around 0.80 g/s. These findings were consistent with similar studies and China's ammonia source inventory.