二元含汞重金属混合物对费氏弧菌的联合毒性研究

Study on the combined toxicity of binary heavy metal mixture to Vibrio fischeri

以费氏弧菌（Vibrio fischeri）作为毒性测试物种,测定了Hg^2＋、Pb^2＋、Cu^2＋、Cd2＋、Zn^2＋、Cr^6＋对费氏弧菌的单一毒性;采用等毒性配比法研究了Hg^2＋/Pb^2＋、Hg^2＋/Cr^6＋、Hg^2＋/Cu^2＋、Hg^2＋/Zn^2＋、Hg^2＋/Cd2＋5种二元混合体系的联合毒性作用。结果表明,重金属离子单独存在时均会对费氏弧菌产生毒性作用,发光菌的相对发光强度均与重金属离子质量浓度呈负相关关系,线性相关系数为0.876 4-0.973 0。Hg^2＋、Pb^2＋、Cu^2＋、Cd2＋、Zn^2＋、Cr^6＋单独存在时对费氏弧菌的EC50分别为0.045 mg/L、0.181 mg/L、0.300 mg/L、0.117 mg/L、0.614 mg/L、23.000 mg/L,重金属离子毒性从大到小为Hg^2＋、Cd2＋、Pb^2＋、Cu^2＋、Zn^2＋、Cr^6＋。而与单一重金属相比,其二元混合物对费氏弧菌的生物毒性效应和强度完全不同。Hg^2＋/Pb^2＋、Hg^2＋/Cr^6＋二元混合体系表现为拮抗作用,Hg^2＋/Cu^2＋、Hg^2＋/Zn^2＋均表现为协同作用,Hg^2＋/Cd2＋表现为加和作用。

The present paper is aimed at introducing our study results of the combined toxicity of binary heavy metal mixture to Vibrio fischeri. As is known,with the fast industrial development,heavy metal pollution has become one of the main problems in environmental protection and human health-care. In combating such pollution problems,we have made it clear that it would be possible for us to use the bioluminescence of luminescent bacteria to identify the toxicity of the environmental toxicants including heavy metals. As a result,we have set up a goal to take Vibrio fischeri as our research topic,trying to find the toxicity of Hg^2 ＋,Pb^2＋,Cu^2 ＋,Cd^2 ＋,Zn^2 ＋,Cr^6 ＋to Vibrio fischeri while investigating the combined toxicity of Hg^2 ＋/ Pb^2＋, Hg^2 ＋/ Cr^6 ＋, Hg^2 ＋/ Cu^2 ＋,Hg^2 ＋/ Zn^2 ＋,Hg^2 ＋/ Cd^2 ＋. The results of our exploration and experiment show that the heavy metals have toxic effects on Vibrio fischeri at different degrees. For example,in single toxicity tests for single pollutant,we can find that there exists a significant negative correlation between the relative luminous intensity and the heavy metal ion concentration. For instance,the correlation coefficients for the regression equation have been found 0. 876 4-0. 973 0,whereas the EC50 of Hg^2 ＋,Pb^2＋,Cu^2 ＋,Cd^2 ＋,Zn^2 ＋,Cr^6 ＋to Vibrio fischeri turned to be 0. 045 mg / L,0. 181 mg / L,0. 300 mg / L,0. 117 mg / L,0. 614 mg / L,23. 000 mg / L,respectively. This reveals a descending order of the seriousness of the toxicity of Hg^2 ＋,Cd^2 ＋,Pb^2＋,Cu^2 ＋,Zn^2 ＋,Cr^6 ＋,that is to say,Vibrio fischeri is sensitive to Hg^2 ＋and is tolerable to Cr^6 ＋.In addition,we have made an evaluation of the combined toxicity with the equal toxicity ratio method. Thus,the toxicity of the binary heavy metal mixture tends to be totally different from that of the single heavy metals,showing that the EC50 of Hg^2 ＋/ Pb^2＋,Hg^2 ＋/ Cu^2 ＋,Hg^2 ＋/ Cd^2 ＋,Hg^2 ＋/ Zn^2 ＋,Hg^2 ＋/ Cr^6 ＋to Vibrio fischeri is 1. 50 mg / L,0. 95 mg / L,0. 99 mg / L,0. 92 mg / L,5. 84 mg / L,respectively. However,when the organisms were exposed to the equitoxic mixtures,it has been found that antagonistic effects in Hg^2 ＋/ Pb^2＋mixtures,which implies that the combined effects of Hg^2 ＋and Pb^2＋tends to make the toxicity reaction dropped. Besides, similar effects can also be found between Hg^2 ＋and Cr^6 ＋,though the mixtures of Hg^2 ＋/ Cu^2 ＋and Hg^2 ＋/Zn^2 ＋are likely to produce synergistic effects on Vibrio fischeri,which means the toxicity of the individual heavy metal tends to be enhanced by the combined effects of the two toxicants. However,the toxicity of Hg^2 ＋to Vibrio fischeri has been found unchanged by the addition of Cd^2 ＋,suggesting that the interaction of Hg^2 ＋and Cd^2 ＋turns to play an additive function in the reaction process.