基于多种方法评价巢湖流域水体中PAHs的生态风险

Using Multiple Methods to Assess the Ecological Risk of Polycyclic Aromatic Hydrocarbons (PAHs) in the Waters from Chaohu Lake Watershed

为了客观评价多环芳烃(PAHs)对水生生态系统的影响,应用了商值法(risk quotients, RQ)、物种敏感性分布模型(sensitivity species distribution, SSD)和概率风险评价法(probabilistic risk assessment, PRA)分别评价了巢湖流域62个表层水体中PAHs单一污染物和混合物的生态风险。结果表明:高分子量PAHs具有较高RQ值,除5个采样点BaA的RQ值大于1.0外,其它均低于1.0。基于TEF转化计算获得混合物mRQ均值为1.58 ±2.68,37.1%的样品mRQ值大于1.0,反映了PAHs混合物对巢湖流域水体存在一定的健康影响。分别采用Log-normal、Log-logistical、BurrIII和Rewibull模型构建了8种PAHs的物种敏感性分布模型(SSD),并根据BurrIII模型计算了各污染物的影响物种比例(PAF)。其中7个采样点BaP的PAF值大于5%,其余采样点PAHs的PAF值均较低,反映了BaP对巢湖流域水体存在一定影响。根据PRA模型构建了环境暴露浓度与毒理浓度分布的联合概率曲线(JPC),并计算了8种PAHs的联合生态风险(msPAFRA)高于HU加和法(msPAFHU)。结果显示所有8种PAHs均呈现较低的生态风险,其中Pyr和BaP的风险较大。比较三种方法发现,巢湖流域水体中高分子量PAHs对生态健康影响较大,而低分子量影响较小,且单一污染物的水生环境影响较小,但混合物的联合风险较大。

In order to comprehensively understand the ecological impacts of polycyclic aromatic hydrocarbons (PAHs), risk quotients (RQ), sensitivity species distribution (SSD) and probabilistic risk assessment (PRA) models were employed to assess the individual and mixture risks of PAHs in 62 surface water samples collected in Chaohu Lake watershed. The results show that RQ values of high weight molecular PAHs were higher than those of low weight molecular compounds. Average RQ values for all PAHs in all samples except for BaA in 5 samples were lower than 1.0, but the TEF based mRQ values for mixture PAHs in 37.1% of samples were higher than 1.0 with mean values 1.58 ±2.68, indicating the potential impacts of PAHs on the water quality in Chaohu Lake watershed. SSD models were built using Log-normal, Log-logistical, BurrIII and Rewibull equations for 8 PAHs. BurrIII based PAF value for BaP was higher than 5% in 7 sampling sites, and the values of PAF for remaining PAHs were generally low. The values of msPAFRA for mixture PAHs in water samples were generally higher than those of msPAFHU. The results of joint probability curves (JPC) for environmental exposure concentration and toxicity data of 8 PAHs also suggest low ecological risks of PAHs in water of Chaohu Lake watershed. The results of three risk assessment modes also showed that higher risks of heavy weight molecular PAHs than those of light weight molecular PAHs to the water environment. Furthermore, there were negligible impacts of individual PAH compound on the water quality of Chaohu Lake watershed, but the mixture of PAHs posed high risks on the ecological system.