为探究重金属复合污染对轮虫的毒性影响,以萼花臂尾轮虫为受试动物,选择Cu2+、Zn2+、Cd2+、Cr6+和Mn2+等5种重金属,采用水生毒理联合效应相加指数法开展了其24 h联合急性毒性作用的评价研究。结果显示,Cu2+、Zn2+、Cd2+、Cr6+和Mn2+等5种重金属对萼花臂尾轮虫24 h半数致死浓度分别为：0.00616 mg•L￣1,12.62 mg•L￣1,2.89 mg•L￣1,17.29 mg•L￣1和67.32 mg•L￣1。联合急性毒性实验结果显示,等毒性配比的Cu2+￣Cr6+(0.00385￣10.806 mg•L￣1)和等浓度配比的Cu2+￣Zn2+(0.0199￣0.0199 mg•L￣1)、Cu2+￣Cd2+(0.0181￣0.0181 mg•L￣1)、Cu2+￣Cr6+(0.0118￣0.0118 mg•L￣1)、Zn2+￣Cd2+(3.475￣3.475 mg•L￣1)二元联合测试液的作用结果显示为拮抗效应,其余二元联合测试液的作用结果则均显示是协同效应。等毒性配比的Cu2+￣Cr6+￣Mn2+(0.00210￣5.902￣22.981 mg•L￣1)和等浓度配比的Cu2+￣Cd2+￣Mn2+(0.00727￣0.00727￣0.00727 mg•L￣1)三元联合测试液的作用结果显示为拮抗效应,其余三元联合测试液的作用结果则均显示是协同效应。等浓度配比的Cu2+￣Zn2+￣Cd2+￣Cr6+(0.00907￣0.00907￣0.00907￣0.00907 mg•L￣1)、Cu2+￣Zn2+￣Cd2+￣Mn2+(0.00898￣0.00898￣0.00898￣0.00898 mg•L￣1)、Cu2+￣Zn2+￣Cr6+￣Mn2+(0.00819￣0.00819￣0.00819￣0.00819 mg•L￣1)四元联合测试液的作用结果显示为拮抗效应,其余四元联合测试液的作用结果的则均显示是协同效应。 Cu2+￣Zn2+￣Cd2+￣Cr6+￣Mn2+等毒性(0.00074￣1.520￣0.348￣2.082￣8.107 mg•L￣1)和等浓度(0.00582￣0.00582￣0.00582￣0.00582￣0.00582 mg•L￣1)配比的五元联合测试液作用结果均显示是协同效应。%Rotifers are one of the important groups of zooplankton in freshwater ecosystem and are recognized as ideal bioassay animals for toxicity tests because of their small size, short generation time, and rapid reproduction rate. In order to investigate the toxic effects of combined pollution of heavy metal on the rotifers, the 24 h com￣bined acute toxicities of Cu2+, Zn2+, Cd2+, Cr6+, and Mn2+to Brachionuscalycifloruswere evaluated using the addi￣tive index of coeffects for aquatic toxicology. The 24 h single toxicity test showed that the median lethal concentra￣tions (LC50) of Cu2+, Zn2+, Cd2+, Cr6+, and Mn2+to B.calycifloruswere 0.00616 mg•L￣1, 12.62 mg•L￣1, 2.89 mg•L￣1, 17.29 mg•L￣1, and 67.32 mg•L￣1, respectively. The 24 h combined acute toxicity of Cu2+￣Cr6+(0.00385￣10.806 mg•L￣1) was antagonism when the toxicity ratio of the two was 1:1, which is similar to the Cu2+￣Zn2+(0.0199￣0.0199 mg•L￣1),Cu2+￣Cd2+(0.0181￣0.0181 mg•L￣1),Cu2+￣Cr6+(0.0118￣0.0118 mg•L￣1), and Zn2+￣Cd2+(3.475￣3.475 mg•L￣1) combined at the concentration ratio of 1:1. The actions of the other binary mixtures were all synergism re￣gardless of the combined pattern. Both the 24 h combined acute toxicities of Cu2+￣Cr6+￣Mn2+(0.00210￣5.902￣22.981 mg•L￣1) and Cu2+￣Cd2+￣Mn2+(0.00727￣0.00727￣0.00727 mg•L￣1) were antagonism when combined at the toxicity ratio of 1:1:1 and the concentration ratio of 1:1:1, respectively. The actions of the other ternary mixtures were all synergism. At the concentration ratio of 1:1:1:1, the 24 h acute combined toxicities of Cu2+￣Zn2+￣Cd2+￣Cr6+(0.00907￣0.00907￣0.00907￣0.00907 mg•L￣1 ), Cu2+￣Zn2+￣Cd2+￣Mn2+(0.00898￣0.00898￣0.00898￣0.00898 mg•L￣1 ), and Cu2+￣Zn2+￣Cr6+￣Mn2+(0.00819￣0.00819￣0.00819￣0.00819 mg•L￣1 ) were all antagonism. The actions of the other quaternary mixture were all synergism. The 24 h combined acute toxicities of the Cu2+￣Zn2+￣Cd2+￣Cr6+￣Mn2+ were synergism when combined at the toxicity ratio of 1:1:1:1:1 (0.00074￣1.520￣0.348￣2.082￣8.107 mg•L￣1 ) and the concen￣tration ratio of 1:1:1:1:1 (0.00582￣0.00582￣0.00582￣0.00582￣0.00582 mg•L￣1 ). The present results indicated that the pat￣tern of combination should be fully considered when evaluating the combined acute toxicity of metal mixtures.
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