运用相对组成探针技术研究青藏高原POPs大气传输与来源

摘要

为探讨青藏高原大气POPs(持久性有机污染物)空间分布趋势、来源和传输特征,应用POPs相对组成探针技术对16个大气被动采样观测点的数据进行分析,将青藏高原空间尺度上的采样点聚为不同的组,以探讨污染物来源及大气传输过程.结果表明:青藏高原大气中的HCB(六氯苯)主要来自于本地燃烧,其中人类活动较为频繁的城镇(波密、格尔木、玉树、拉萨、工布江达、拉孜、那曲)具有较高的HCB相对组成(25％～74％).青藏高原南缘(包括珠峰、然乌、萨嘎)以南亚正在使用的农药——HCHs(六六六)和α-Endo(硫丹)为特征(二者的相对组成之和超过了40％),凸显了南亚污染排放经长距离传输对青藏高原的影响.剔除HCB影响后,青藏高原中部、东南部河谷地区(鲁朗、拉孜、拉萨、日喀则、工布江达、昌都)及那曲、狮泉河因具有较高的o,p'-DDT相对组成而聚为一组,平均值为40％,表明这些采样点可能受到本地污染排放的影响.%Based on the proportion of individual chemical to the total amount of persistent organic pollutants (POPs) (relative compositions) and cluster analysis, the probe technique of POPs' relative composition was conducted to investigate the sources and long-range atmospheric transport of POPs across the Tibetan Plateau. In this study, the published data of 16 passive sampling sites were employed, and sampling sites (across the Tibetan Plateau) with similar chemical sources were clustered into different groups. Focusing on each group, the probable POPs source as well as regional or long distance transport contributions can be inferred. The results indicated that the local emission was the major source of atmospheric hexachlorobenzene (HCB) on the Tibetan Plateau, and its high relative compositions (25% -74% ) appeared in sites close to cities/towns where anthropogenic activities were intensive ( e. g. , Bomi, Golmud, Yushu, Lhasa, Lhaze, Gongbog'Yamda, Lhaze and Nagqu). The sites near southern fringe of the Tibetan Plateau (i.e. , Everest, Ranwu and Saga) had high relative compositions (more than 40%) of hexachlorocyclohexanes (HCHs) and a-Endosulfan (current-used pesticides in India), implying the long-range atmospheric transport from South Asia. When excluding HCB in cluster analysis, the sampling sites in mountain valleys (Lunang, Lhaze,rnLhasa, Xigaze, Gongbog'Yamda, Qamdo) , Nagqu, and Gar were classified into the same cluster due to their higher compositions of o, p'-DDT (mean value 40%). The local agricultural usage of dicofol was the most likely source for o, p'-DDT.