中文摘要：

2006年8月～2007年7月,在西藏拉萨市西郊（29°38′N,91°01′E）采集了30个大气总悬浮颗粒物（TSP）样品,利用14C定量区分了碳质气溶胶的生物和化石来源并分析了其季节变化特征.结果表明,碳质气溶胶中生物碳所占比例的fc值在0.357～0.702之间变化,均值为0.493,明显高于东京和北京等大城市地区的fc均值,但低于Launceston等郊区或偏远地区的fc均值,说明拉萨碳质气溶胶的生物来源占较大比例.fc值季节变化明显,冬季的均值最大,春季逐渐降低,夏、秋季较低.冬季高值与拉萨西郊当地居民使用木材、农业废弃物、干牛粪等燃料的能源结构密切相关;夏、秋季fc值低说明化石碳的增加,与旅游旺季机动车尾气排放增加等相关.δ^13TC变化范围为-26.4‰～-25.1‰,年均值为-25.8‰,其季节变化特征并不明显,但夏季δ^13TC偏大可能与化石碳增多有关.全年碳质气溶胶的δ^13TC变化范围很小,结合fc值的季节变化推断拉萨碳质气溶胶总体上受到生物质燃烧和机动车尾气等几个均匀混合的稳定来源影响.

英文摘要：

A total of 30 samples of total suspended particles were collected at an urban site in western of Lhasa city,Tibet from August 2006 to July 2007 for investigating carbonaceous aerosol features. 14C was taken as a reference to quantitatively distinguish the fossil and biogenic-derived origins along with the characteristics of seasonal variations of all carbonaceous materials in Lhasa are discussed. The results showed that the fc values in Lhasa ranged from 0. 357 to 0. 702,with an average of 0. 493,which is higher than Beijing and Tokyo,but are far lower than that of remote/rural regions such as Launceston,indicating a major biogenic influence in Lhasa. Values of fc displayed clear seasonal variations with higher mean value in winter,a decreasing trend in spring,while relatively lower values in summer and autumn. Higher fc values in winter demonstrate that carbonaceous aerosol is mainly dominated by wood burning and incineration of agricultural wastes during the winter. The lower fc values in summer and autumn might be caused by increased diesel engines,motor vehicles emissions,which are related to the tourism in Lhasa. δ^13 values ranged from - 26. 40‰ ～ - 25. 10‰,with an average of - 25. 8‰,and showed no clear seasonal variation. The relative higher values in summer reflected the increment of fossil carbon emissions. ^13 CTC values are relatively homogeneous at - 25. 8‰,considering the characteristics of seasonal variations of fc values,it can be concluded that carbonaceous aerosol of Lhasa was mainly influenced by a constant mixing of several pollution sources such as motor vehicles and wood burning emissions.