Acute and joint toxicity of Cu~(2+)、Zn~(2+)、Co~(2+)、Ni~(2+) and Li~+ to Daphniopsis tibetana Sars
摘要
Toxic effects of Cu2+,Zn2+,Co2+,Ni2+ and Li+ on Daphniopsis tibetana were tested in laboratory.The results of acute toxic test showed that D.tibetana had high tolerance to the 5 metals,and the order of the toxicity of these metals to D.tibetana was Cu2+ Zn2+ Co2+ Ni2+ Li+.The values of 24 h EC50 of the 5 metals on D.tibetana were 12.75 mg/L,18.32 mg/L,83.26 mg/L,196.97 mg/L and 386.34 mg/L,respectively,and were 3.27 mg/L,4.96 mg/L,27.49 mg/L,66.09 mg/L and 325.42 mg/L for 48 h,respectively.The results of joint toxicity showed that the effects of equivalent toxicity of Cu+Zn,Co+Ni,Co+Li,Ni+Li,Co+Ni+Li,Cu+Zn+Co and Cu+Zn+Co+Ni+Li on D.tibetana were antagonistic,but the effects of equivalent toxicity of Cu+Zn+Ni,Cu+Zn+Li and Cu+Zn+Co+Ni were antagonistic at 24 h,while synergetic at 48 h.From the results we can speculate that D.tibetana has high tolerance to metal ions and combination of metal ions.Particularly,D.tibetana always show antagonism to combinations containing Li +.These two aspects,rapid growth and fast reproduction,could be explained as adaptive mechanism of D.tibetana under high concentrations of metals in saline lakes in Tibet,especially under high concentration of Li+.