辽河和太湖沉积物中PAHs和OCPs的分布特征及风险评估

摘要

Surface sediment samples were collected from Liaohe and Taihu. Polycyclic aromatic hydrocarbons (PAHs) and organic chlorine pesticides (OCPs) in the sediment samples were determined with GC/MS.The concentrations of the total PAHs in Liaohe and Taihu varied in the range of 120.8～22120ng/g (dry weight, dw) and 256.6 ～1709ng/g (dw), with the mean concentrations of 3281ng/g and 829.0ng/g respectively. Tetra and penta～hexa-cyclic compounds were the main PAHs compounds in the sediments of both areas and fluoranthene was predominant. The results of source apportionment indicated that PAHs in both areas were mainly due to the pyrogenic sources. ∑OCPs in Liaohe and Taihu were relatively lower and were dominated by β-HCH, suggesting no new source of HCHs. Equilibrium partitioning approach was used to derive the sediment quality criterias (SQCs) for PAHs and OCPs. Based on the SQCs, risk assessment was conducted to evaluate the ecological risk of PAHs and OCPs in the sediments. In some sites of Hunhe, the total sediment toxicity unit ∑ESBTUFCV was larger than lfor PAHs, HCHs and DDTs, suggesting high environmental risk in Hunhe. The risk in sediment of Tai lake was acceptable for PAHs, HCHs and DDTs.%于2009年6月分别采集辽河和太湖表层沉积物样品,测定了多环芳烃(PAHs)和有机氯农药(OCPs)的含量.结果表明,辽河表层沉积物中∑PAHs含量(干重)为120.8～22120ng/g,平均值为3281ng/g,处于较高的水平;太湖∑PAHs的含量为256.6～1709ng/g,均值为829.Ong/g,处于中等水平.两采样区的PAHs以4环和5～6环为主,荧蒽最高,PAHs主要因热解产生.辽河和太湖表层沉积物中OCPs的含量均处于较低水平,且均以β-HCH为主.利用相平衡分配法建立了15种PAHs和8种OCPs的沉积物基准值,对沉积物中PAHs和OCPs进行了生态风险评估,结果显示辽河流域的浑河段均有∑PAHs、∑DDTs和∑HCHs超标点位,具有较大的生态风险;太湖流域未发现超标点位,沉积物中各类污染物中含量均未超过基准值,生态风险较小.