低浓度下4个取代苯污染物与硝酸铅的混合对发光菌的联合毒性

多种污染物混合特别是低浓度下的混合对生物的联合毒性是生态毒理学研究的热点之一。选择了3类污染物苯酚、间甲基苯酚、苯胺、对硝基苯胺、硝酸铅,采用美国微板光度计测定了它们对发光菌青海弧菌-Q67(Vibrio-qinghaiensis sp.-Q67)的单一及联合毒性。应用非线性拟合技术模拟了这5种物质及其混合物的剂量-效应曲线,硝酸铅可用Logit模型模拟,其它4个物质能用Weibull模型准确描述,所有拟合相关系数在0.98以上,均方根误差在0.02以下。根据纯物质的EC50值,获得这5个物质的毒性强弱顺序:硝酸铅〉对硝基苯胺间甲基苯酚苯酚苯胺。混合实验设计了各物质在EC50、EC1、无观察效应浓度(no observed effect concentration,NOEC)比例的混合。用浓度加和(dose addition,DA)和独立作用模型(independent action,IA)对混合物毒性进行预测。IA基本准确预测了这5个物质在各自EC50混合的毒性。DA与IA模型都稍微过高地预测了以EC1及NOEC浓度比例混合的联合毒性,但都在毒理学实验容许的范围之内。这5个物质以NOEC混合时对测试生物Q67没有产生明显毒性,但是还不能判定这些物质在此浓度下混合是安全的。污染物在各自的NOEC浓度下混合是否对其它生物有潜在的威胁还需更多毒理学实验支持。

Combined toxicity of four substituted benzene pollutants and lead nitrate at low concentrations on photobacteria

Combined toxicity of multi-component mixture (especially at low concentrations) to biology is a hot issue in the field of ecotoxicology. The toxicity of each component and the combined toxicity of mixtures on Vibrio-qinghaiensis sp.-Q67 were deter-mined by micro-plate Luminometre in this study. The components investigated included phenols (phenol and 3-methyl-phenol), ani-lines (aniline and p-nitroaniline), and lead nitrate. The Dose-Response curves of these substances were obtained by non-linear fitting. The experimental data of p-nitroaniline and those of the other four components were well simulated by the Logit model and the Weibull model, respectively, with all related coefficients above 0.98 and root mean square errors below 0.02. According to EC_(50) val-ues of these compounds, the toxicity rank was obtained: lead nitrate) p-nitroaniline)3-methyl-phenol)phenol)aniline. In the ex-periments on combined toxicity, three mixtures of EC_(50), EC_1, and no observed effect concentration (NOEC) of these five components were prepared, respectively. Dose addition (DA) and independent action (1A) models were used to predict combined toxicity of these mixtures. It was found that IA was able to accurately predict the toxicity of the mixture at EC_(50). Both models slightly overestimated the combined toxicity of the mixtures at EC_1 and NOEC, but the predicted results were in the allowed range of toxicological experi-ments. No significant toxicity from the mixture at NOEC of these compounds on Q67 was observed, but this does not indicate that the mixture of these compounds at NOEC is safe to the other organisms. Further toxicological experiments need to be carried out to prove whether there is potential risk to other organisms resulting from mixture of multi-pollutant at NOEC.