采用静水体外暴露法，根据Cd2＋和 Hg2＋的24 h全致死和无死亡质量浓度区间，按等对数间距设立6个质量浓度组，即Cd2＋为25．00、52．23、109．13、228．00、476．37、993．27 mg／L ，Hg2＋为3．00、7．26、17．58、42．57、103．06、249．53 mg／L ，研究了Cd2＋和Hg2＋对体质量48．58～87．09 g的中华绒螯蟹的急性染毒；以Cd2＋、Hg2＋的96 h半致死质量浓度为一个毒性单位，按照毒性比1∶1设置5个质量浓度组研究了镉－汞联合毒性。4 d的试验结果表明，Cd2＋对中华绒螯蟹的24、48、72、96 h的半致死质量浓度分别为654．226、192．429、70．767、40．279 mg／L ；Hg2＋对中华绒螯蟹的24、48、72、96 h的半致死质量浓度分别为164．157、19．214、6．738、3．641 mg／L ，Hg2＋对中华绒螯蟹的毒性比Cd2＋明显。Cd2＋、Hg2＋对中华绒螯蟹的安全质量浓度分别为4．994 mg／L和0．079 mg／L。Hg2＋和Cd2＋联合作用对中华绒螯蟹24、48、72、96 h的相加指数分别为4．291、4．587、3．367和2．003，具有显著的协同效应。%Chinese mitten handed crab Eriocheir sinensis with body weight of 48 .58—87 .09 g was exposed to Cd2+ concentrations of 25 .00 ,52 .23 ,109 .13 ,228 .00 ,476 .37 and 993 .27 mg/L and Hg2+ concentra‐tions of 3 .00 ,7 .26 ,17 .58 ,42 .57 ,103 .06 and 249 .53 mg/L ,respectively ,and jointly by mixing equitoxic ratio of 96 h‐median lethal concentrations (LC50 ) of Cd2+and Hg2+ for 4 days to understand the acute tox‐icity effect of Cd2+ and Hg2+ on survival of the crab .The results showed that the LC50 of Cd2+ were 654 .226 mg/L in 24 h ,192 .429 mg/L in 48 h ,70 .767 mg/L in 72 h ,and 40 .279 mg/L in 96 h ,and the LC50 of Hg2+ were 164 .157 mg/L in 24 h ,19 .214 mg/L in 48 h ,6 .738 mg/L in 72 h and 3 .641 mg/L in 96 h .The safety concentrations (SC) were shown to be 4 .994 mg/L for Cd2+and 0 .079 mg/L for Hg2+ , higher toxicity in Hg2+ than in Cd2+ .The joint toxicity test revealed that the additive index (AI) was 4 .291 in 24 h ,4 .587 in 48 h ,3 .367 in 72 h and 2 .003 in 96 h for equitoxic mixtures of Hg2+ and Cd2+ , showing the synergistic joint toxic effects of Cd2+ and Hg2+ .
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