畜禽源氨气排放因子估算方法研究

畜禽养殖过程中产生的氨气(NH_3)在人为源NH_3排放中所占的比重较大,对二次气溶胶的形成起重要作用.由于我国畜禽饲养品种多样,各地气候条件和饲养规模存在较大差异,且影响NH_3排放的因素复杂多变,因此,获得准确的畜禽NH_3排放因子较为困难.本文以山西省太原市及其周边地区典型猪场、鸡场、牛场、羊场为实验场所,以杜洛克猪与长白猪的杂交猪、海兰褐蛋鸡、白羽肉鸡、杜泊羊与晋中绵羊的杂交羊、中国黑白花奶牛、金色阿奎丹与西门塔尔杂交肉牛为研究对象,通过3种方法估算它们的NH_3排放因子.结果表明:基于日粮成分和氮代谢沉积率的粗蛋白估算法过程简单、计算便捷、适合所有种类的畜禽,但未考虑NH_3挥发过程中的吸收转化及施肥利用,因而误差较大;基于排泄物含氮率和NH_3挥发率的物质流法涉及粪肥管理的不同阶段,全面考虑了NH_3产生、损失的全过程,与实际情况接近,但参数较多、周期较长、计算过程复杂;基于畜禽舍内NH_3浓度的直接测量法数据来源可靠、参数少,但只能用于相对封闭的环境,不适合牛场和羊场等敞开或半敞开的圈舍,且该方法没有考虑粪尿离开畜禽舍以后的储藏、还田过程,计算结果偏小.通过3种方法的互相印证和比对,猪、奶牛、肉牛、羊、蛋鸡、肉鸡6种实验动物的NH_3排放因子分别为6.90、36.53、22.99、3.94、0.54、0.46 kg·头(只)~(-1)·a~(-1).本研究可以为我国畜禽源NH_3排放因子的本地化测定提供一定的参考,并为准确估算畜禽NH_3排放量、做好农业源NH_3排放清单编制和污染防治工作提供参考.

Estimation of ammonia emission factors for livestock and poultry breeding

Livestock mature could be a dominate source in ammonia emissions in China. It is difficult to measure the emission factors (EFs) of ammonia because they vary with meteorological parameters, animal housing conditions and feed stuff types or feeding periods, etc. In this study, six typical livestock categories in Shanxi Province, i.e. the cross pigs of Duroc and Landrace, HY-Linne Brown laying hens, White Feather broilers, Chinese Holstein cattle, the hybrid sheep of Dorper and Jinzhong sheep, and the cross beef cattle of Golden Aguirre and Simmental, were selected to estimate their NH₃ EFs by using three methods. The results showed that the crude protein estimation method based on the dietary and nitrogen metabolism was simple, practical, common, and convenient, but with larger errors caused by neglecting the absorption, transformation, and reuse of NH₃ in the field. The mass flow estimation method based on the nitrogen content from the excretion and NH₃ volatilization rate was relatively reasonable; however, it would take a long time and its parametrization could be relatively complex. The method of direct measurement of NH₃ concentrations needed less parameters, but it was only appropriate for a relatively closed environment and completely neglected NH₃ emissions during composting. Therefore, all three methods should be used for better understanding of the ammonia emissions from livestock manure. The NH₃ EFs were calculated as 6.90, 36.53, 22.99, 3.94, 0.54, 0.46 kg·animal^-1·a^-1 for the chosen pigs, cows, beef cattle, sheep, laying hens, and broiler, respectively. The results could be used for developing NH₃ emission inventory and air pollution control.