祁连山七一冰川雪冰和冰川融水中正构烷烃和多环芳烃的分布特征及来源研究

Aliphatic and Polyaromatic Hydrocarbons in Snow/Ice and Glacier Meltwater in the Qiyi Glacier,Qilian Mountains:Sources and Distribution

2008年6月,在祁连山七一冰川采集雪坑、冰川融水和冰川末端冰样,经过大孔吸附树脂富集后,用GC-MS对样品中的正构烷烃(nC14～nC32)和多环芳烃进行了分析.结果表明,正构烷烃的含量在冰川融水中最高,雪坑次之,冰中最低;多环芳烃的含量在雪坑中最高,冰中最低,冰川融水界于二者之间.正构烷烃与多环芳烃都具有很强的疏水性,在固-液相分配过程中倾向于保留在残留固相中.由于冰川融水样品距冰川末端约1km,沿途地表土壤和植被会贡献部分正构烷烃,所以冰川融水中正构烷烃的含量最高.与正构烷烃不同,多环芳烃较易挥发,而且易被沿途土壤和植被所吸附,导致冰川融水中多环芳烃的含量降低.冰川末端冰中正构烷烃与多环芳烃的含量都很低,可能是由于冰川末端冰年代比较古老,受人类活动的污染较轻.正构烷烃的碳优势指数(CPI值)表明,七一冰川中的正构烷烃主要来自高等植物蜡和化石燃料燃烧产物的混合物,多环芳烃的荧蒽/芘(Fla/Pyr)和菲/蒽(Phe/Ant)比值表明,七一冰川冰雪和冰川融水中检测到的多环芳烃主要来自化石燃料的不完全燃烧.

Snow,glacier meltwater and glacier bottom ice were collected from the Qiyi Glacier,Qilian Mountains,in June 2008,of which n-alkanes（nC14~nC32）and PAHs were analyzed by GC^MS,after being enrichment by resin.The results showed that the content of n-alkanes in glacier meltwater was the highest,followed by that of snow and that of glacier bottom ice.While the PAHs content in snow was the highest,followed by that of glacial meltwater and that of bottom ice.Due to the high hydrophobicity,n-alkanes and polycyclic aromatic hydrocarbons tend to remain in the residual solid phase in the solid-liquid distribution processes.As the glacier meltwater is taken about one kilometer away from the glacier terminus,the surface soil and vegetation in both sides of the drainage route will contribute n-alkanes to the water sample partly.Therefore,the content of n-alkanes in glacier meltwater would be the highest.In contrast to n-alkanes,volatile PAHs may be emitted to atmosphere or sorpted by soil and vegetation during snowmelt,resulting in low content of polycyclic aromatic hydrocarbons.The contents of n-alkanes and PAHs in glacier bottom ice were all low,which may be due to the aged glacier bottom ice and light pollution from human activity.The CPI values further indicated that n-alkanes in this study were derived from plant waxes and fossil-fuel combustion products.The ratios of Phenanthrene/Anthracene and Fluoranthene/Pyrene can be used as a method to identify the major source of PAHs,coal combustion and vehicle pollution.