藻类叶绿素荧光对除草剂生物毒性响应特性的研究

Study on Biological Toxicity Response Characteristics of Algae Chlorophyll Fluorescence to Herbicides

以蛋白核小球藻、铜绿微囊藻、斜生栅藻为敏感藻,研究了莠去津、敌稗、敌草隆、灭草松四种除草剂及其混合剂对藻类光合特性的影响规律,实验同时确定了三种微藻荧光对除草剂的最佳响应时间。实验结果表明,除草剂显著降低了藻细胞类囊体膜中光系统Ⅱ的最大光合效率(Fv/Fm)、实际光合效率(Y(Ⅱ))、绝对电子传递速率(ETR)和光化学猝灭系数(qP),而非光化学猝灭系数(qN)呈现上升趋势,400μg·L^(-1)敌草隆使蛋白核小球藻Fv/Fm参数值下降了41%。实验选用的三种实验藻在四种除草剂单独和混合胁迫下均发生了不同程度的光抑制效应,表现出光合效率、电子传递速率、光合活性的降低和光保护能力的增强,藻类自身具有一定的光保护机制可以降低除草剂的影响。除草剂能够影响藻细胞叶绿素荧光强度,其中灭草松对蛋白核小球藻的影响最为显著,在400μg·L^(-1)灭草松影响下蛋白核小球藻的叶绿素荧光强度下降了44%。

Chlorella pyrenoidosa,Microcystis aeruginosa and Scenedesmus obliqnuswere selected as sensitive algae in this experiment.The effect of microalgae Phtosynthesis characteristic was studied after exposure of 4 kinds of herbicides(Atrazine,Diuron,Propanil and Bentazone)and its mixture.Meanwhile,the best response time of microalgae fluorescence to the herbicides was determined inthis study.The results showed that 4 selected herbicides significantly reduced the algal cells in the thylakoid membrane of light systemⅡmaximum photosynthetic efficiency(Fv/Fm),the actual photosynthetic efficiency(Y(Ⅱ)),the absolute electron transport rate(ETR)and photochemical quenching coefficient(qP),however,increased non-photochemical quenching coefficient(qN)with the increasing herbicide dosages.The Chlorella pyrenoidosa at 400μg·L-1 Diuron had the largest decrement of Fv/Fm(41%).Algae all displayed the effects of different degree on photoinhibition in conditions of 4 kinds of herbicides individual and mixing stressing,with the decrease of photosynthetic efficiency,electron transfer rate and photosynthetic activity,but increase of light protection ability.Algae itself had a certain light protection mechanism that could reduce the influence of herbicides stress.Herbicides affected the intensity of chlorophyll fluorescence,in which the effect of Bentazone on Chlorella pyrenoidosa was the most significant.The intensity of Chlorella pyrenoidosa chlorophyll fluorescence at 400μg·L-1 Bentazonehad the largest decrement(44%).