苯、苯酚、硝基苯对绿水螅的联合毒性

采用单一毒性方法测定了苯、苯酚、硝基苯溶液处理绿水螅的半致死浓度（LC50）：苯酚和硝基苯对绿水螅的毒性较强，苯对绿水螅的毒性较弱．采用相加指数法，按等毒性单位1：1分别研究了三种苯类药物复合污染物的联合毒性：苯一苯酚和苯酚一硝基苯对绿水螅的联合毒性，暴露时间为24h、48h、72h的AI分别为0．135，0．771，0．490和0．312，0．153，0．664，均表现为协同作用；硝基苯一苯对绿水螅的联合毒性，暴露时间为24h、48h的AI为-0．455，-0．112，为拮抗作用，72h的AI为0．401，为协同作用．在三个时间段的实验中，绿水螅对苯酚和硝基苯毒性反应强烈，对苯和苯联合物的毒性反应均较弱．

Joint Toxicity of Benzene, Phenol and Nitrobenzene on Chlorohydra sp

A single toxicity method was applied to mensurate the semi-lethal concentration （LC50） of benzene, phenol and nitrobenzene to Chlorohydra sp. The results showed that toxic effect of Phenol and Nitrobenzene on Chlorohydra sp. was more greater than Benzene. An additive index method was used to investigate the joint toxicity of Chlorohydra sp. that was treated by joint toxipolluting of three benzene drugs. In joint toxicity test, at toxicity of 1 ： 1, the results showed that joint toxipolluting of Benzene and Phenol, Phenol and Nitrobenzene, the addition index （AI） of expose time 24 h,48 h and 72 h were 0. 135, 0. 771, 0. 490 ; and 0. 312, 0. 153, 0. 664, which could be explained as synergistic action. The joint toxipolluting of Benzene and Nitrobenzene the addition index（AI）of expose time 24h and 48 h were -0. 455,- 0. 112, due tO antagonistic action; however, in 72 h ,AI was 0. 401, it showed synergistic action. At the three treatment intervals, Phenol and Nitrobenzene were more toxic, while Benzene and joint toxicity with Benzene were slightly less toxic to Chlorohydra sp.