基于发光细菌法的水体重金属标准限值毒性评价

Toxicity assessment of standards of heavy metals in water based on luminous bacteria method

目的评价我国GB 3838—2002《地表水环境质量标准》和GB 8978—1996《国家污水综合排放标准》中各重金属限值的毒理学安全性。方法采用发光细菌法(受试菌种费氏弧菌)检测8种重金属(Cu、Zn、Cd、Hg、Cr、As、Pb、Ni)的急性毒性,建立重金属浓度与发光抑制率的线性回归方程,计算半数致死(半抑制)浓度(EC50)值;并对GB 3838—2002《地表水环境质量标准》和GB 8978—1996《国家污水综合排放标准》中8种重金属标准限值进行毒性等级评价。结果各重金属毒性大小顺序为Pb>Hg>Zn>Cu>As>Cr>Cd>Ni;水质标准和排放标准中重金属阈值大部分处于无毒或低毒范围,但GB 3838—2002《地表水环境质量标准》中总铜和总锌处于重毒和高毒范围,GB 8978—1996《国家污水综合排放标准》中总铅、总铜和总锌处于高毒～剧毒范围。结论本次实验结果从一个侧面反映了我国水体中部分重金属阈值可能偏高。

Objective To evaluate toxicological safety of standard of heavy metals in the Environment Quality Standards for Surface Water （GB 3838-2002） and Integrated Wastewater Discharge Standard （GB 8978-1996）. Methods The toxicity of eight kinds of heavy metals （Cu, Zn, Cd, Hg, Cr, As, Pb and Ni） were detected by using luminescent bacteria method,and the linear regression equation of heavy metals concentration and luminous inhibition rate was built, and the median lethal concentration values （EC50） were calculated. Toxicological safety of standard for eight kinds of heavy metals in the Environment Quality Standards for Surface Water （GB 3838-2002） and Integrated Wastewater Discharge Standard （GB 8978-1996） were evaluated. Results The toxicity of heavy metals ranked as Pb〉Hg〉Zn〉Cu〉As〉Cr〉Cd〉Ni. The limits of most heavy metals were in the levels of nontoxicity or low toxicity,however the limits of the total copper and total zinc in the Environment Quality Standards for Surface Water （GB 3838-2002） were in the level of high toxicity,and the limits of the total lead,total copper and total zinc in the Integrated Wastewater Discharge Standard （GB 8978-1996） were in the levels of high toxicity to extremely toxicity. Conclusion The limits of some heavy metals in water may be on the high side.