应用淡水发光细菌测定土壤Cu急性毒性的影响因素研究

在环境污染物的毒性评价和监测中，发光细菌法是一种具有快速、灵敏和廉价等优点的直接生物测试方法。鉴于海水发光细菌在土壤中应用的局限性，本文拟应用淡水发光细菌青海弧菌Q67（Vibrio—qinghaiensis sp．-Q67）进行土壤中Cu的毒性测定，并对其在土壤Cu急性毒性测定的影响因素进行了研究，包括pH对青海弧菌Q67发光的影响，背景溶液的选择及0．01mol·L^-1 CaCl2对毒性测定的影响，以期确定淡水发光细菌测定土壤Cu急性毒性最佳条件。结果表明，青海弧菌Q67可以应用于pH范围在5．5～9．0之间的样品；不同的背景溶液中，青海弧菌Q67在高浓度人工土壤溶液中的发光最稳定，且不同背景溶液对Cu的毒性测定影响差异不显著，因此，推荐高浓度人工土壤溶液作为青海弧菌Q67应用于土壤样品毒性测定的背景溶液；常用的土壤浸提剂0．01mol·L^-1 CaCl2显著降低了Cu的毒性（全Cu表示）。研究结果对青海弧菌Q67毒性测试方法的建立和在土壤中的应用提供了非常重要的依据。

Factors on Application of Bioluminescent Bacteria to Measure Acute Toxicity of Copper in Soils

Bioluminescent bacterial test is a rapid and cost-effective bioassay for risk assessment and monitoring of environmental pollutants. However, there are some limitations when the bioluminescent bacteria from seawater, such as Vibriofischeri, were used in soils because rela- tively high concentration of NaCl was added in the tested samples. In tile present study, the bioluminescent bacteria Vibrio-qinghaiertsis sp.- Q67 from freshwater was used to develop a bioluminescent bacterial bioassay. The factors and conditions affecting the acute toxicity of copper in soils were investigated, including pH, background solutions and the extractant of 0.01 mol· L^-1 CaCl2. The results showed that Q67 was suitable for the samples of pH 5.5-9.0 in soil environments. According to the bioluminescence and Cu toxicity measured using Q67 in different background solutions, it was found that the bioluminescence of Q67 was more stable in an artificial soil solution with about 0.01 mol· L^-1 electrolytes than in other solutions （an artificial soil solution with about 0.001 mol· L^-1 electrolytes, artificial lake water, 0.1 mol·L^-1 KCl and 0.1 mol·L^-1 CaCl2）, so that the artificial soil solution with about 0.01 mol· L^-1 electrolytes was suggested as the background solution for bioluminescent bacterial bioassay with Vibrio-qingbaieusis Q67. It was also found that the solution of 0.01 mol·L^-1 CaCl2, which was often used as a soil extractant, decreased significantly the toxicity of total Cu in solutions. These results will be helpful to develop a bioluminescent bacterial bioassay for acute toxicity measurement of heavy metals in soils.