| Ammonia in the atmosphere has direct or indirect influence on several environmental issues, such as acid deposition, low-visibility, greenhouse effect, eutrophication, soil acidification, etc. It is estimated that the global atmospheric emissions of ammonia has greatly exceeded its removal. The anthropogenic ammonia emission is mainly from agriculture, of which the animal husbandry contributes the most. Due to animal husbandry locates in the rural areas or in the suburbs, the ammonia emissions from livestock and other agricultural sources together with pollutants form city sources, cause the regional environmental problems. Therefore, the study of the ammonia emission from livestock is important.Based on the mass-flow methodology, this study analyzed the transformation and migration of nitrogen in the animal husbandry. According to the Chinese practice of livestock production and the researches on environmental hygienics and coprology of animal, and nutriology of plant, the nitrogen excretion per animal was verified to match the situation in China. And then using nitrogen volatilization rates in different stages of the manure management (housing, grazing, manure storage and field application)the ammonia emission factors (EFs)for each animal category were modified; the amount of livestock bred, served as activity level, was from the statistics yearbooks. Thus, the ammonia emission inventories from livestock in China, in Guangdong Province and in Pearl River Delta region were compiled respectively at different spatial resolution in the year of 2005. The national emission inventory from 1998 to 2006 was also compiled under the same methodology.The ammonia emission from livestock in China in 2005 is 8.204 Mt NH3-N with the share of major sources as follows, yellow cattle(bos primigenius)25.6%, fattening pig 19%, goat 9.9%, sheep 8.9%, laying hen 8%. The provincial contribution rates of each main source have highly agreement with the livestock industry zoning. Henan Province made the largest emission, accounting for 9.73% of the whole country, followed by Shandong, Hebei, Sichuan and other provinces. The ammonia emission density is 0.855 t NH3-N/km2, of which the emission density of Tianjin is the largest, reaching 5.308 t NH3-N/km2, followed by Shandong, Henan, Hebei, Shanghai, Beijing and other provinces and cities, which are mainly locate in the mid-east of China. The estimated historical trend of ammonia emission from 1998 to 2006 indicated the average growth rate is 3.41% during those years. And from 2000 to 2005 a rapid increase is seen. The main emission sources remained the same (yellow cattle, fattening pig, goat, sheep, laying hen)except for the changes in their shares, which was the result of the restructuring in national animal husbandry.The activity level in Guangdong emission inventory was adjusted to suit the practice in Guangdong. In 2005, the ammonia emission from livestock in Guangdong was 236 kt NH3-N, which accounted for 2.38% of the country according to the same caliber. The spatial distribution of emission showed that the east part of Guangdong emitted less than the west part, and the coastal cities emitted less than the mountainous cities. Maoming, Zhanjiang, Zhaoqing were the top three cities in emission, accounting for a total share of 34% in the province. The provincial emission density of ammonia was 1.32 t NH3-N / km2 with a similar spatial distribution of emission. Foshan is the city where emission density is the largest, reaching 3.21 t NH3-N/km2. Fattening pig is the most important source in Guangdong, with the contribution rate of 38.97%, followed by yellow cattle and broiler, which accounted for 15.17% and 14.16% respectively. The main region of livestock production is in the western Guangdong, in particular, Maoming and Zhanjiang.The ammonia emission from livestock in the PRD in 2005 was 71.3 kt NH3-N, accounting for 30.2% of Guangdong, and 0.72% of China. Dongguan emitted the most (6.1 kt NH3-N), followed by Sihui, Gaoyao. The ammonia emission density in the PRD was 1.71 t NH3-N/km2, higher than that of Guangdong. The distribution of emission density clearly indicated a gradual increase to the northwest. The zone with the highest ammonia emission density of the PRD was Huicheng (9.73 t NH3-N/km2), followed by Dinghu and Duanzhou. Fattening pig, broiler and geese are the dominant sourses in the PRD, with a total share of 73.2%. Compared the emission density with similar economic regions, the PRD was of similar level to Taiwan, but higher than the Yangtze River Delta, while lower than the Beijing-Tianjin-Hebei; in the two core cities in the PRD, emission density of Guangzhou was lower than all the Municipalities except Chongqing, while that of Shenzhen was lower than the all the four municipalities.According to the N volatilization contribution rate at each stage of manure management, this study offered some of the abatement measures at farm scale. And based on the regional comparison, this study proposed some advice to policy makers. |
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