被动加标在水生生态风险评价中的应用——以多氯联苯分配系数的测定为例

Application of Passive Dosing in Aquatic Ecological Risk Assessment: A Case Study of Measuring Partition Coefficients of Polychlorinated Biphenyls

准确的水生生态风险评价需要可靠的毒性数据,而其获取要求在一定时间范围内,水体中污染物的浓度保持恒定。对疏水性有机污染物进行水体生物毒性测试时,通常采用有机溶剂加标,然而该方式可能因为污染物的挥发和降解、容器壁吸附、生物摄取等问题,水体中污染物浓度持续下降,导致污染物的浓度-效应关系难以明确。近期为了克服这些问题,被动加标用于替代溶剂加标,通过污染物在加标体系中平衡分配来维持精确和恒定的水体浓度,同时还可通过测定加标聚合物中污染物的浓度来监测水体浓度。首先介绍了被动加标方法及其材料选择,讨论了该方法在生态风险评价中的主要应用,包括分配系数的测定、体外细胞测试、体内生物积累及毒性测试,以及沉积物毒性评价等。然后,以测定代表污染物多氯联苯在聚二甲基硅氧烷与水间的分配系数为例,详细说明被动加标的操作流程。最后,讨论了被动加标方法的优缺点,并对其在水生生态风险中的应用前景进行了展望。

To conduct aquatic ecological risk assessment, credible toxicity data are required, and maintaining stable water concentrations of test contaminants for certain time are the premises of accurate data. Solvent dosing has been conventionally used in aquatic toxicity testing with hydrophobic organic contaminants （HOCs）, however, continuous reduction in chemical concentrations in water was frequently observed due to volatilization and degradation of chemicals, glassware binding and uptake by organisms. As a consequence, it is hard to achieve accurate concentration-response relationships for test HOCs. To overcome these problems, passive dosing has been recently introduced as a replacement of solvent dosing. Through the equilibrium partitioning of chemicals within dosing systems, HOCs＇ concentrations in water could be stabilized and monitored by quantifying chemical concentration in polymers. The definition and material selection of passive dosing are introduced and the recent applications of this method in ecological risk assessment are summarized, including the measurements of chemi＇cal partition coefficients, in vitro cell assays, in vivo bioassays, and sediment toxicity evaluation. Then, the procedures of passive dosing are detailed using a case study of measuring partition coefficients of polychlorinated biphenyls between polydimethylsiloxane and water. Lastly, the perspective of passive dosing in aquatic ecological risk assessment is discussed.