中文摘要：

铁路是中国重要的交通运输方式,但中国至今尚无铁路运输行业大气污染物排放的报道.根据中国铁路部门逐年统计数据,采用基于燃料消耗量的排放因子法,估算了1975～2007年中国铁路机车大气污染物排放量,并分析了大气污染物排放强度及其变化.结果表明,33年来中国铁路机车烟尘、SO2、CO和CnHm排放量逐年降低,分别由1975年的351.06、39.97、84.60和84.53万t降至2007年的7.87、1.14、3.67和2.64万t,年均减排量分别为10.70、1.21、2.53和2.56万t.但NOx排放量呈上升趋势,由1975年的3.48万t增至2007年的9.83万t,年均增加0.20万t.烟尘、SO2、CO和CnHm的排放强度呈现明显的降低趋势,其值分别由1975年的68.62、7.81、16.54和16.52×10-4 kg.（t.km）-1降至2007年的0.54、0.08、0.25和0.18×10-4kg.（t.km）-1,NOx的排放强度在0.5～0.8×10-4 kg.（t.km）-1范围内波动.中国铁路运输行业大气污染物排放量占全国总排放量的比重较低,加上其排放强度还逐年降低,因此可以说铁路运输是中国交通运输领域中理想的节能减排运输方式.

英文摘要：

Although railway has played a great role in transportation in china,there has been no any study on air pollutants emissions of locomotives until now.Based on the annual statistical data collected by the Chinese Railway Statistic Center,using the emission factor method derived from fuel consumption,the air pollutants emissions of locomotives during 1975-2007 were calculated,and their emission intensities and dynamic characteristics were analyzed.The results show that the emissions of soot,SO2,CO and CnHm from steam and diesel locomotives in china decreased from 3510.6 thousand,399.7 thousand,846.0 thousand and 845.3 thousand ton in 1975 to 78.7 thousand,11.4 thousand,36.7 thousand and 26.4 thousand ton in 2007,indicating a decrease of 107.0 thousand,12.1 thousand,25.3 thousand and 25.6 thousand ton per year,respectively.However,the emissions of NOxshowed an increase trend from 34.8 thousand ton in 1975 to 98.3 thousand ton in 2007 with an increase rate of 2.0 thousand ton per year.The emission intensities of soot,SO2,CO and CnHm decreased significantly from 686.2,78.1,165.4 and 165.2 g/（hundred converted ton-km） in 1975 to 5.4,0.8,2.5 and 1.8 g/（hundred converted ton-km） in 2007,respectively.The emission intensity of NOxfluctuated in the range of 5.0-8.0 g/（hundred converted ton-km）.Air pollutants emissions of locomotives accounted for very little of the total emissions in China,and the emission intensities decreased persistently.It shows that railway transportation is a perfect way of saving energy and reducing emission in the sector of transportation.