外秦淮河疏浚后底泥中多环芳烃分布特征及其变化

Characterization and Change of Polycyclic Aromatic Hydrocarbons in Sediment from Waiqinhuai River

利用GC-MS对外秦淮河疏浚后3个月及6个月采集的13个底泥样品中16种优控多环芳烃（PAHs）进行了分析.结果表明，疏浚后3个月底泥中PAHs含量较低，疏浚后6个月PAHs含量明显上升，说明疏浚对减少水体底泥污染确实有效果，但保持时间不长，经过一段时间的沉积和富集后污染物含量会发生回复现象，外源输入和河道沉积物内源释放对疏浚后新生表层底泥PAHs含量有较大的贡献. 草场门和集庆门河段处底泥中PAHs含量较高. 底泥中的PAHs以4～6环高分子量的PAHs为主，低环PAHs所占比例春季比冬季高. 根据PAHs中特殊组分（菲/蒽和荧蒽/芘）比例（ω（Phe）/ω（An）, ω（Flu）/ω（Pyr））判断外秦淮河表层底泥中的多环芳烃主要来源为石油产品燃烧.

GC-MS technique was applied to analyze 16 priority-controlled polycyclic aromatic hydrocarbons （PAHs） in sediment samples from 13 sites collected three months and six months after dredging of the Waiqinhuai River. The results show that in the first three months after sediment dredging, the sediment PAHs concentrations are low; but after another three months, the concentrations begin the increase again. It indicates that sediment dredging is effective for reducing pollutants in sediments, but it cannot last for a long time. Pollutants are able to increase again after a period of deposition and accumulation. Exogenous input and release of river sediment play a very important role for PAHs increasing in the sediment. High PAHs concentrations can be found in Caochangmen and Jiqingmen. It can be seen that PAHs in the sediments are mainly consist of 4 - 6-ring high molecular weight PAHs, with higher proportion of lower-ring PAHs in spring than in winter. The sources of PAHs were evaluated employing ratios of specific PAHs compounds, such as ω（Phe） / ω（An） and ω（Flu） / ω（ Pyr）. The results indicates that the Waiqinhuai River was mainly contaminated by petrogenic PAHs.