Measurement of Ammonia and Hydrogen Sulfide Emission from Three Typical Dairy Barns and Estimation of Total Ammonia Emission for the Chinese Dairy Industry

Simple Summary Ammonia (NH3) and hydrogen sulfide (H2S) are obnoxious gases with characteristic odors. They are environmental contaminants and could be harmful to animals and humans. Measurement of NH3 and H2S from dairy farms is still limited, especially for Chinese dairy farms. In this study, we measured ammonia and hydrogen sulfide from 11 barns from 3 dairy farms in central China during winter. Next, we calculated the average daily emission rates for these two gases. Finally, we extrapolated our results to estimate the NH3 emission from the Chinese dairy production. There is an urgent need for accurate measurement for emissions of ammonia (NH3) and hydrogen sulfide (H2S) in dairy barns in order to obtain reliable emission inventories and to develop and evaluate abatement strategies. This experiment was performed on three dairy farms in central China during 14 consecutive days in the winter 2020. Concentrations of NH3 and H2S were measured every two hours. The samples were taken inside and outside of barns from 7 sites at two heights (at floor and 1.5 over the floor). The results show that the average NH3 concentration was 2.47 mg/m(3) with a maximum of 4.62 mg/m(3), while the average H2S concentration was 0.179 mg/m(3) with a maximum of 0.246 mg/m(3). Lactating cows produced significantly more NH3 (3.73 mg/m(3) versus 2.34 mg/m(3)) and H2S (0.24 mg/m(3) versus 0.14 mg/m(3)) than non-lactating cows. NH3 and H2S concentrations were higher at 0 m than at 1.5 m, especially during the day. In addition, the average daily emission rates per animal unit (AU = 500 kg weight) were 23.5 g and 0.21 g for NH3 and H2S, respectively. The emission rate for NH3 was then used to extrapolate the NH3 emission from the Chinese dairy production. Our estimation for 2016 was 0.45 Tg, and it could reach 1.35 Tg by 2050. These numbers reflected our first attempt to calculate emission inventories for the Chinese dairy industry. Our results also suggest that more concrete measures must be taken to reduce the uncertainties of NH3 emissions from dairy cow production in China.