五种重金属对蛋白核小球藻的动态毒性研究

Study on the Dynamic Toxiciy of Five Heavy Metals on Chlorella Pyrenodosa

以蛋白核小球藻为受试生物,以五种常见的重金属(铜、锰、镉、锌和铅)为研究对象,应用时间依赖微板毒性分析法系统测定不同浓度的五种重金属分别对蛋白核小球藻在7个不同暴露时间(12、24、36、48、60、72和96 h)的动态生长抑制效应数据,应用非线性最小二乘法拟合在不同暴露时间测定的浓度-效应数据。结果表明,两参数非线性函数Logit能够较好地拟合五种重金属对蛋白核小球藻在除了暴露时间12 h外的浓度-效应数据(R>0.91,RMSE<0.1);五种重金属对蛋白核小球藻的毒性先随着时间的延长而逐渐增加,在一定时间后,毒性几乎不再增加,即具有明显的的时间依赖性,但不同重金属随暴露时间的延长,其毒性变化规律不同,如铜、镉和锌的毒性从暴露时间12 h时就开始逐渐增强,在24 h增加速度最快,然后缓慢增加至72 h后几乎不再增加,而锰和铅的毒性在开始的12 h内几乎没有毒性,此后开始迅速增加,铅在24 h内的抑制效应甚至超过了50%,锰在24 h和48 h两个时间点迅速增加,然后毒性几乎不再增加;不同重金属的毒性大小顺序随时间的变化规律也不相同。

Chlorella pyrenoidosa(C.pytenoidosa)being taken as the test organism and five kinds of common heavy metals(Cu,Mn,Cd,Zn and Pb)as the resarch objects,the dynamic growth inhibition toxicity data of five heavy metals with different concentrations towards C.pytenoidosa at seven different exposure times(12,24,36,48,60,72and96h)were determined by time-dependent toxicity microplate analysis method.The obtained concentration-toxicity data were fitted by nolinear least squar method.The results showed that the concentration-toxicity data of five heavy metals towards C.Pytenoidosa at different exposure times except that of12h could be well fitted by nonlinear Logit function with two parameters.The toxicity of the five heavymetals towards C.pytenoidosa augmented with the exposure time lengthening at first,then almost not increased after some times,i.e.the toxicity of the five heavy metals displayed time-depedency.The toxicity changing laws of different heavy metals varied at different exposure times,eg.the toxicity of Cu,Cd and Zn increased gradually from the exposure time of12h,then rapidly at24h,very slowly at72h and thereafter kept steadily.As for Mn and Pb,almost no toxicity exhbited in the first12h,then increased rapidly and the toxicity effect of Pb exceeded50%at24h.The toxicity of Mn increased rapidly at the exposure time of24h and48h,and almost no longer increased after that.The toxicity effects order of the five heavy metals was different with the exposure time varying.