北京特大降尘事件研究:饱和烃分布模式及其环境意义

A heavy dust fall in Beijing: Distribution characteristics and environmental significance of saturated hydrocarbons

2006年4月16~17日,北京市发生了一次强降尘事件。采集了降尘样品并对其饱和烃成分进行分析,结果显示:降尘样品饱和烃中的正构烷烃呈后峰模式分布,主峰碳数为29,高碳数烷烃具有强烈的奇偶优势。样品中还检出烷基环己烷系列、烷基环戊烷系列、松香亭及其同系物。长链正构烷烃碳同位素组成的测试结果显示,δ13C均值为-33.9‰。通过对比降尘第一物源区中蒙边境、第二物源区毛乌素沙地和沉降区即北京周边的土壤及大气颗粒物饱和烃分布模式、植被类型等可知,降尘饱和烃主要来自于中蒙边境,其次是毛乌素沙地,北京周边输入的份额很少。在未来的亚洲内陆干旱-半干旱区的粉尘起源-传输-沉积模式研究中,应考虑上述过程的影响,以精准恢复古气候和古环境。

A sandstorm event in Beijing occurred in April 16 ~ 17,2006,the dust samples were collected for analyzing the saturated hydrocarbon. The results showed that the distribution of n-alkanes was posterior peak pattern,the main carbon number was 29,and the content of high carbon had strong odd-even predominance. The alkyl cyclohexane series,alkyl cyclopentane series,rosin pavilions and their congeners were also detected in the samples. The carbon isotopic compositions of the long chain n-alkanes indicated that the mean of δ13 C was-33. 9 ‰. By comparing of the saturated hydrocarbon distribution patterns and vegetation types in soil and atmospheric particulate matters that from the China-Mongolia border region,Mu Us Desert and the areas surrounding Beijing,it showed that the saturated hydrocarbon in dust was mainly from the China-Mongolia border region,followed by Mu Us Desert,the share of input around Beijing was small. In the study of the dust source-transport-sedimentary model in the arid-semiarid region of Asia inland,the effects of the above processes should be taken into account in order to restore the paleoclimate and paleoenvironment accurately.