pH对发光菌法测试Cr(Ⅲ)和Cr(Ⅵ)毒性的影响  

The Effect of pH on Cr(Ⅲ) and Cr(Ⅵ) Toxicity to Luminescent Bacteria

作　　者：周伟杰 韩威妺 彭良琼 张文华[2] 石碧[1] 

机构地区：[1]四川大学制革清洁技术国家工程实验室,四川成都610065 [2]四川大学皮革化学与工程教育部重点实验室,四川成都610065

出　　处：《皮革科学与工程》2017年第6期5-9,共5页Leather Science and Engineering

基　　金：国家自然科学基金(21776185);国家重点研发计划(2017YFB0308503)

摘　　要：铬在自然水体中的常见价态有+3价和+6价,发光细菌法是评价其水生态急性毒性的快捷方法。本文以硫酸铬和重铬酸钾为试剂,明亮发光杆菌为受试生物,系统研究了pH对细菌发光强度以及对Cr(Ⅲ)和Cr(Ⅵ)毒性测定的影响。结果表明,明亮发光杆菌在pH 4~9范围内,发光稳定;测试EC50值配制的系列Cr(Ⅲ)、Cr(Ⅵ)溶液,浓度相差200倍,pH差异显著。采用HCl或Na OH溶液调节待测液pH,暴露15 min,在pH=4和5时Cr(Ⅲ)的EC50值分别为169.46 mg·L^(-1)和261.75 mg·L^(-1);制革用铬粉对发光细菌的EC50值远高于相应pH的硫酸铬;pH升高Cr(Ⅲ)毒性减小,可能与体系中羟配聚的Cr(Ⅲ)物种丰度的增加有关。当溶液pH从4升高到9,Cr(Ⅵ)的EC50值从24.03 mg·L^(-1)减小为11.16 mg·L^(-1),Cr(Ⅵ)的毒性远高于Cr(Ⅲ)。Chromium mainly exist as hexavalent species（Cr（Ⅵ）） and trivalent species（Cr（Ⅲ）） in natural aquifers. The Microtox bioassay is convenient to test the acute toxicity of heavy metal in water environment. In this paper,Photobacterium phosphoreum was used as biological target to investigate the effect of pH on luminescent bacteria, and on the toxicity of Cr（Ⅲ） and Cr（Ⅵ） by using chromium sulfate and hexavalent potassium dichromate respectively. The results showed luminescent bacteria was steady under the pH range of 4 to 9. As for Cr（Ⅲ）, with the increase of pH from 4 to 5,the EC50 values of Cr（Ⅲ） increased from 169.46 mg·L^-1 to 261.75 mg·L^-1, indicating decreasing toxicity with increasing pH. The pH dependence of Cr（Ⅲ） toxicity might be due to the formation of hydroxo complex, which could be inferred further from the higher EC50 values of basic chromic sulfate. However, Cr（Ⅵ） at low concentrations（11.16 mg·L^-1） was very toxic to Photobacterium phosphoreum, and showed increasing toxicity with increasing pH.

关 键 词：PH 发光细菌 毒性 铬 

分 类 号：X172[环境科学与工程—环境科学]