重金属与农药污染物对青海弧菌Q67拮抗作用的定量评估

Quantitative evaluation on the antagonism between heavy mental and pesticide pollutants to Vibrio qinghaiensis sp.-Q67

重金属与农药对生态环境造成的污染日益严重.为了探究重金属与农药混合污染物对生态环境的影响,以重金属铅(Pb)和两种农药(甲霜灵(MET)、草甘膦(GLY))为目标污染物,应用均匀设计射线法(UD-Ray)设计三元混合物体系,共5条具有不同浓度比的射线,运用时间毒性微板分析法(t-MTA)系统测定重金属与农药及其三元混合物对水生生物青海弧菌(Vibrio qinghaiensis sp.-Q67,Q67)在不同暴露时间的毒性,应用浓度加和(CA)模型分析混合物组分间的毒性相互作用,绝对残差(dCA)模型定量评估相互作用强度.结果表明,3种污染物对Q67的毒性随时间变化规律不同,均具有明显的急性毒性,但GLY和Pb不具有明显的时间依赖毒性,而MET随暴露时间延长毒性逐渐增加,即具有明显的时间依赖毒性;不同暴露时间,污染物的毒性大小顺序不同,如暴露时间点为0.5 h时,毒性大小顺序为:GLY>Pb>MET,而在12 h时,毒性大小顺序为:GLY>MET>Pb.3种污染物的混合体系的5条混合物射线(U1—U5)的毒性却与MET呈相似的时间变化规律,即具有时间依赖毒性.依据CA,重金属和农药三元混合体系(Pb-MET-GLY)的毒性相互作用为拮抗作用.5条混合射线的dCA均大于0,且随着暴露时间、暴露浓度及组分浓度比的改变而改变,即三元混合体系具有明显的时间和浓度依赖拮抗作用;5条射线的最大dCA值均大于50%,其中U4在2 h时dCA最大值可达70%.

Heavy metal and pesticide pollutions are becoming more and more serious.To explore the combined effects of heavy metal and pesticide pollutants on the ecological environment,one heavy mental:lead(Pb)and two pesticides:metalaxyl(MET)and glyphosate(GLY)were selected as research objects.Toxicity of Pb,MET and GLY together with their ternary mixtures to a freshwater organism Vibrio qinghaiensis sp.-Q67(Q67)was determined in different time by using the time-dependent microplate toxicity analysis(t-MTA)method.Here,ternary mixture systems including five rays with different concentration ratios were designed by the uniform design ray method.Concentration addition(CA)was used to analyze toxicity interactions within mixture systems.The deviation from CA model(dCA)was used to quantitatively evaluate the interaction intensity.The results showed that three pollutants had different toxicity changing trends with time,and all showed obvious acute toxicity towards Q67.GLY and Pb did not have obvious time-dependent toxicity,while the toxicity of MET gradually increases with the extension of exposure time.Toxicity order of three pollutants changed with time.Toxicity orders were GLY>Pb>MET in 0.25 h and GLY>MET>Pb in 12 h,respectively.Toxicity of ternary mixture systems rays(U1—U5)towards Q67 was similar to that of MET displaying time-dependency.According to CA,ternary mixture systems(Pb-MET-GLY)exhibited antagonism.The dCA values of the five mixture rays were above zero,varied with exposure time,concentration and concentration ratios.Antagonism of ternary mixture system was strong,and the maximum dCA values of the five rays were all greater than 50%where the maximum value of U4 was 70%in 2 h.