Characteristics of ammonia emission from large-scale livestock/poultry breeding and its mitigation countermeasures in Chongqing

With environmental concerns raised on air quality and livestock/poultry industries, there has been an increasing pressure on rapidly developing large-scale livestock/poultry breeding to take actions to mitigate these concerns. As such, it was necessary to explore ammonia emission from large-scale livestock/poultry industries and its characteristics for management of air quality and prevention of livestock/poultry pollution driven by sound scientific knowledge and countermeasures. With data on ammonia emission from large-scale livestock/poultry breeding and the related coefficients, this study calculated the amount of ammonia emission in 2013 in large-scale livestock/poultry breeding in Chongqing. The paper also analyzed the characteristics of ammonia emission and the corresponding mitigation countermeasures for large-scale livestock/poultry breeding. The results showed that total ammonia emission from large-scale livestock/poultry breeding in Chongqing was 17 102.92 t in 2013 and the emission intensity was 0.21 t·km^-2. Hechuan, Fengdu and Tongnan were the top three counties for ammonia emission, with their contribution accounting for 30.19% of the total ammonia emission. Jiangbei County had the least ammonia emission in Chongqing. Ammonia emission intensity for Bishan County was the highest, followed by Hechuan County, with respective emission intensity of 1.17 t·km^-2 and 1.09 t·km^-2. Chengkou County had the least, with emission intensity of 0.01 t·km^-2. Based on the spatial distribution characteristics, there was significant spatial auto-correlation in the spatial distribution of ammonia emission from large-scale livestock/poultry breeding industries in Chongqing. Through localized spatial auto-correlation analysis, it was noted that four counties belonged to high-high type, five counties belonged to low-low type and none belonged to high-low type or low-high type of spatial distribution of ammonia emission. Pig breeding was the highest contributor to ammonia emission, with 9 538.63 t of emitted ammonia which accounted for 55.80% of total large-scale live-stock/poultry breeding emission. Then layer breeding accounted for 15.87% and broiler breeding (with the least value) accounted for 6.68% of ammonia emissions. Ammonia emissions from livestock and poultry manure differed in the stages of animal house, storage and utilization of manure. For poultry, ammonia emissions of stage in breeding house were the dominant of overall stages, with a contribution rate of over 60%. For livestock, however, ammonia emission contribution rate at utilization stage was the highest. In order to reduce emissions, it was need to focus on management of dairy cattle breeding. Such management countermeasures included the use of feed stocks with low ammonium content, renovation of stable, covered or sealed manure, and injection application of manure.