多环芳烃是自然界中常见的有机污染物.以多环芳烃(芘)为研究对象,采用实验室培养斜生栅藻(Scenedesmus obliquus)的方法,测定藻细胞密度和光合色素(叶绿素a、叶绿素b、类胡萝卜素)含量的变化,研究不同质量浓度芘对斜生栅藻的毒性效应,设置5个芘质量浓度梯度(5、10、20、30、50 mg·L-1)和1个对照组,通过同期生长的处理组与对照组的藻细胞数进行比较以及抑制率计算对实验结果分析.结果表明:芘对斜生栅藻的生长有一定的抑制作用,随着芘质量浓度增加,斜生栅藻生长受到抑制作用越明显,呈现出良好时间-效应和剂量-效应的关系;经回归分析,求得2 d,4 d和6 d芘抑制斜生栅藻生长的半抑制浓度(EC50)分别为44.07,29.23和20.99 mg·L-1.斜生珊藻的生长率随处理浓度的增加而逐渐降低.同时通过肉眼和显微镜观察,发现斜生栅藻藻的颜色随芘浓度增加从翠绿色变为白色.芘处理斜生栅藻6d后,斜生栅藻光合色素含量和Ca/Cb随芘浓度增加而明显下降,并且变化趋势与生长率基本一致.其中斜生栅藻的叶绿素a含量的减少比叶绿素b和类胡萝卜素快.芘可能通过抑制藻的光合作用产生毒害效应,从而抑制藻类生长.%Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in nature. In this study, a laboratory culture was conducted to examine the toxicity effects of pyrene under different mass concentrations on the growth and the contents of pigments ofScenedesmus obliquus. The exposure mass concentrations of pyrene were 0, 5, 10, 20, 30, 50 mg·L-1. Comparing the numbers of the cells of the treatment with that of the control group at the same time, the data were analysed by the calculating of IR so on. The results showed that the growth of algae was inhibited by pyrene and decreased with the increase of pyrene mass concentration, exhibiting a good time-effect and concentration-effect manners. The 2 d, 4 d and 6 d-EC50 ofScenedesmus obliquuswere 44.07, 29.23 and 20.99 mg·L-1 respectively by regression analysis, The algae growth rates decreased with the increasing of pyrene mass concentration. It can be seen that the color of algal cells changed from green to white. Meanwhile, the contents of the pigments were examined. The total content of pigments and the ratio between chlorophyll a and chlorophyll b decreased significantly with the increasing of pyrene mass concentration and the trends of change were coincident with their specific growth rate. The experimental results indicated that chlorophyll a contents ofScenedesmus obliquus reduced faster than those of chlorophyll b and carotenoid. The ecotoxic effects of pyrene might be ascribed to the inhibition of the algal photosynthesis by pyrene.
展开▼
