摘要:
人类活动导致大量毒害污染物进入水体和沉积物,从而对水生生物产生诸多不利影响。开展毒害污染物的生态风险评价,筛选高风险毒害污染物,是毒害污染物风险管控和生态系统保护的基础。对美国和欧盟等发达国家和地区毒害污染物的生态风险评价方法进行了综述。水体和沉积物中毒害污染物风险评价的基本方法首先是采用预测或测定环境浓度(PEC或MEC)进行暴露评价,用生态毒性的剂量-效应关系推导出的预测无影响浓度(PNEC)进行影响评价,然后以风险商(RQ)进行风险表征。对于沉积物中缺乏毒性数据的有机毒害物则通过有机碳归一化沉积物/水分配系数将沉积物中污染物的浓度转化为孔隙水中的浓度,采用水体评价方法进行评价;对于沉积物中重金属的风险,可采用风险评价码(RAC)或采用酸性可挥发性硫化物(AVS)和同步浸提重金属(SEM)差值法进行表征。据此,提出我国开展流域水体和沉积物中毒害污染物的风险评价体系,为我国毒害污染物的风险管控提供参考。
Abstract:
Numerous toxic pollutants enter into water and sediments due to human activities, thus causing adverse effects on aquatic organisms. Hence, conducting ecological risk assessment of contaminants and screening high-risk contaminants are the basis of risk management of contaminants and ecosystem protection. In this paper, we reviewed the methodologies of ecological risk assessment for toxic pollutants in aquatic environment used in the United States, European Union and other developed countries. Basic methodology of risk assessment for contaminants in surface water and sediments includes the following three processes:(a) Exposure assessment, which is carried out using predicted or measured environmental concentrations (PECs or MECs); (b) Impact assessment, which is performed using predicted no effect concentrations (PNECs) derived from aquatic toxicity data through dose-effect relationship; (c) Risk characterization, which is ranked by risk quotient (RQ) from the ratio of PEC (or MEC) to PNEC. However, for the pollutants lacking toxicity data in sediments, the risk assessment of the organic pollutants can be carried out using the aquatic risk assessment method after obtaining the concentration of the pollutants in pore water, which is calculated from the concentration in sediments according to the organic carbon-normalized sediment/water partition coefficient of the organic pollutant. And for the metal pollutants in sediments, the risk assessments can be characterized by risk assessment code (RAC) or by the subtraction method of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM). Based on the review, we proposed a risk assessment methodology for toxic pollutants in surface water and sediments in China, aiming to provide information for contamination risk management of China.
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