| Ammonia (NH3) is one of the most important trace gases in atmosphere. The volatilization of ammonia is one of important parts in the whole nitrogen cycle. Not only does ammonia emission cause the losses of nitrogen from animal feed and agricultural nitrogen fertilizer, but also aggravates environmental pollution and affects the production and life of mankind. Agro-ecosystem is the main source of ammonia volatilization, accounting for 73% of global ammonia emissions. Sichuan-Chongqing region is located in the Qinghai-Tibet Plateau and the Yangtze River Plain transition zone, where the agricultural production and livestock production are among the best in China. The swine population ranks the first in the country, accounting for 14.5%-17%, and the rural population, total crop harvest area and fertilizer consumption in the country accounted for 9.9%-10.3%,8.5%-8.6% and 6.8%, respectively. Therefore, Research on ammonia emission from Agro-ecosystem of Sichuan-Chongqing region has great significance to understand the process of nitrogen cycle, to develop a reasonable strategy for nitrogen management and protect the ecological environment.In this paper, ammonia (NH3) emission from agro-ecosystem in the Sichuan-Chongqing region during 1990-2004, was estimated by the regional nitrogen cycling model IAP-N, with the county level of agricultural activities data. Sichuan-Chongqing region was divided into four sub-regions in accordance with the geography, and local climate and administrative division. And the spatial and temporal distributions of ammonia emissions were analyzed by Arc-GIS.The results showed that average annual ammonia emission (in nitrogen gauge) from agro-ecosystem in the Sichuan-Chongqing region were 626.7,670.5 and 698.8 GgNH3-N·a-1, Ammonia density were 11,12 and 12 kg NH3-N·hm-2·a-1 in 1990-1994, 1995-1999,2000-2004, respectively. The ammonia emission appeared increasing trend, whereas, the contribution of various ammonia sources presented little change. For instance, in 2000-2004, the contributions of NH3 emission from fertilized cropland, manure management system and field residues burning to the total ammonia emission of agro-ecosystem in the Sichuan-Chongqing region, respectively, were 53%, 46% and 1%, equals to 374.9,318.2 and 5.6 Gg NH3-N·a-1. But the contributions were variable in different regions. Ammonia emission was primarily induced by fertilized cropland in Chengdu Plain and Chongqing hilly Area, whereas, in northwest sub-region of Sichuan province was manure management system. The geographical distribution of ammonia emission from agro-ecosystem in the Sichuan-Chongqing region was generally "east high and west low". Ammonia emissions in sub-regions of Chongqing hilly Area, Chengdu Plain, Southwest and northwest sub-regions were 165.6,408.8,85.9 and 38.8 Gg NH3-N·a-1, respectively, in 2000-2004.At the same time, Ammonia density were 20 and 28 kg·hm-2·a-1 in sub-regions of the Chongqing hilly Area and the Chengdu Plain, whereas,9.1 and 1.6 kgNH3-N·hm-2·a-1 in Southwest and northwest sub-regions, respectively. The about results will provide a scientific basis for policy maker to make fertilizer effectively applied and mitigate NH3 and GHG emissions from agro-ecosystem of Sichuan-Chongqing Region. |
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