Acute toxicity of triazophos acephate and phoxim on juveniles Acanthopagrus schlegel from Zhoushan Sanxin Mariculture Co LTD was done from July to August 2008.The weight and length of the juvenile was(5.09±0.71) cm and(2.09±0.66) g respectively.The result indicated that the orders of the toxicity of these three pesticides on juveniles Acanthopagrus schlegel was triazophos>phoxim>acephate.We found that the median-lethal concentrations(LC50) in 24 h,48 h,72 h,96 h to juveniles Acanthopagrus schlegel were 30.11 mg/L,21.83 mg/L,17.30 mg/L and 14.07 mg/L for acephate respectively;0.68 mg/L,0.49mg/L,0.34 mg/L and 0.30 mg/L for phoxim,respectively ;0.068 mg/L,0.060 mg/L,0.054 mg/L and 0.051 mg/L for triazophos respectively.And the safe mass-concertrations of acephate,triazophos and phoxim to juveniles Acanthopagrus schlegel was 1.41 mg/L,0.005 mg/L and 0.03 mg/L respectively.Finally,the thesis discussed the characters of acute toxicity,the effects and the saf-concentration of these pesticides to juveniles Acanthopagrus schlegel.

Juveniles Sparus macrocephalus,with length of 5.09±0.71 cm and weight of 2.09±0.66 g,have been chosen as the subjects of our experiment which has been done to investigate the influences of acute toxicity of four kinds of heavy metal on juveniles Sparus macrocephalus.The experiment is done with water temperature(28.8±1.6) ℃ and pH 8.24.The results of the experiment indicate that the median-lethal concentrations(LC50) in 24 h,48 h,72 h,96 h to juveniles Sparus macrocephalus are 11.53 mg/L,10.15 mg/L,6.56 mg/L,6.09 mg/L for Zn2+ respectively;31.48 mg/L,24.31 mg/L,23.01 mg/L,23.01 mg/L for Cr6+ respectively;2.75 mg/L,1.55 mg/L,1.30 mg/L,1.06 mg/L for Cu2+ respectively and 0.098 8 mg/L,0.098 1 mg/L,0.089 2 mg/L,0.074 2 mg/L for Hg2+ respectively.The degrees of the intensity of the toxicity of these four kinds of heavy metal on juveniles Sparus macrocephalus are Hg2+Cu2+Zn2+Cr6+ succesively.Finally,this paper has discussed the poisoning features of ions of heavy metals,the impact of acute toxicity of heavy metal on juveniles Sparus macrocephalus in the stage of their early growth,toxicity evaluation,as well as the control of the ions of heavy metals in water.

Acute toxicity and joint toxicity of Hg2+,Cr6+,Cu2+,and Zn2+ on Bullacta exarata are studied.The animals were in average shell height of 17.35±1.01 mm,collected in Daixi Town,Daishan County of Zhengjiang Province,from July to August in 2006.The result indicates that the resistance of Bullacta exarata against the four heavy metals decreases slowly as the experiment time lasted.The degree of the toxicity is in the order of Cu2+Hg2+Zn2+Cr6+.The median lethal concentrations(LC50) of the metals at 96 hours to the animal are 0.001 1,0.630,1.94,and 9.44 mg/L,respectively.The effects of the joint toxicity,which acted on Bullacta exarata at 96 h by the combinations of any two of Hg2+,Cr6+,Cu2+,and Zn2+,is closely related to the matching of the four heavy metal ions.Finally,the thesis talked about the acute toxicity effects,SC and the joint toxicity of Hg2+,Cr6+,Cu2+,and Zn2+ on Bullacta exarata.

The thesis studied on the acute toxicity of Cr6+,Zn2+,Hg2+ on megalopa larvaes of Portunus trituberculatus The results showed that the median lethal concentrations(LC50) of Zn2+,Cu2+,Hg2+and Cr6+ for 96 h to megalopa larvaes of Portunus trituberculatus was 1.040 mg/L,0.291 mg/L,0.034 mg/L and 11.046 mg/L respectively,that safety concentrations(SC) of Zn2+,Cu2+,Hg2+and Cr6+ for 96 h was 0.010 4 mg/L,0.002 91 mg/L,0.000 34 mg/L and 0.114 6 mg/L respectively;that the order of the toxicity of these heavy metals was Hg2+Cu2+Zn2+Cr6+ in turn.Finally,the thesis talked about the acute toxicity effects,SC of Zn2+、Cu2+、Hg2+and Cr6+ on megalopa larvaes of Portunus trituberculatus.