基于物种敏感性分布的保护海水水生生物的石油烃急性毒性基准研究

溢油污染对水生生物的危害以及分散剂使用对原油毒性的影响一直是溢油应急响应及危害评估时关注的焦点。本研究收集筛选了基于标准测试方法的90组急性毒性数据(LC50/EC50),其中37组毒性数据来自15种油品的水容纳组分(water accommodated fraction,WAF),53组来自11种化学分散剂与15种油品的分散液(chemically dispersed water accommodated fraction,CEWAF),应用物种敏感性分布(species sensitivity distribution,SSD)方法推导了基于水生生物保护的石油烃总量(total petroleum hydrocarbon,TPH)的急性毒性基准值,同时还分析了分散剂和不同暴露方式对原油毒性的影响。结果显示,以名义浓度(nominal concentrations)所表示的毒性结果可能高估分散剂对原油毒性的影响,基于CEWAF和WAF的LC50/EC50所推导的有害浓度(HC5s)差异较小,计算出的保护水生生物TPH急性毒性基准值为0.38 mg·L-1(TPH);鱼类对原油污染的响应明显敏感于甲壳类;同时证明了SSD方法在溢油毒性评估及风险阈值推导中具有可行性和合理性。

Development of Acute Aquatic Toxicity Criteria for Total Petroleum Hydrocarbon in Oil Spill Based on Species Sensitivity Distributions

The impact of oil spill on aquatic organisms and the influence of dispersants on the toxicity of crude oil have been main concerns in emergency response and risk assessment of oil spill. In this study, a total of 90 toxicity data obtained using standard test methods were selected and applied in the derivation of acute toxicity benchmark of total petroleum hydrocarbon for aquatic organism protection and hazard concentrations (HCs) through species sensitivity distribution (SSD) method. The 90 toxicity data contain 37 sets of data from water accommodated fraction of oil (WAF) and 53 sets of data from chemically dispersed water accommodated fraction of oil (CEWAF) including 15 oils and 11 dispersants in 22 species. Fifth percentile hazard concentrations (HC₅s) were calculated from the SSDs and used to assess the effects on water column biota by chemically treated oil spills and the impacts of exposure test conditions (flow, semi-static, and static) on the development of toxicity benchmarks. Results expressed by nominal concentrations possibly overestimate the toxicity of CEWAF compared with that of WAF, while there was only small difference in the HC5s derived based on WAF and CEWAF. The derived aquatic toxicity criteria value by SSD for a short exposure was 0.38 mg·L^-1 (TPH). Fish is more sensitive to oil than crustacean. Application of SSDs appears to be a feasible and reasonable approach to develop oil toxicity criteria and assess risks of oil spill.