电阻抗图谱法对重金属污染的毒理学响应及机理研究

The response of electrical impedance spectroscopy parameters as extracellular resistance, intracellular resistance, relaxation time and distribution coefficient of relaxation time of ryegrass roots to seed germination rate, the inhibition rate of root elongation and the inhibition rate of bud elongation under stress of single and combined pollution of Cu2+, Cd2+ and Pb2+ ions are studied, which are cultured in nutrient solution and soil. Electrical impedance spectroscopy parameters , the content of heavy metal (which includes total content, the content of metal in different extracted forms and different subcellular fractions) and physiological parameters characterizing eco-toxicity including antioxidant enzyme activity(SOD, POD, CAT), relative conductivity, moisture content, MDA, soluble protein and soluble sugar of ryegrass roots, stem, and leaves are measured under above stress state. Electron microscope analysis is made with the samples. The change of electrical impedance spectroscopy parameters of ryegrass roots, stem and leaves, the relationship between physiological parameters and electrical impedance spectroscopy parameters, dose effect relationship between electrical impedance spectroscopy parameters and the content of heavy metal are tried to find. Toxic effect of heavy metal ions is indicated and pollution level of heavy metal ions in water and soil is diagnosed with electrical impedance spectroscopy parameters. The cause for response of electrical impedance spectroscopy parameters to heavy metal pollution may be explained through micro mechanism.

通过研究重金属铜、镉、铅单一及复合污染下，溶液和土壤培养的黑麦草根的电阻抗图谱参数（胞外电阻、胞内电阻、弛豫时间和弛豫时间分布系数）对种子发芽率，根伸长抑制率及芽伸长抑制率的响应，测定了在重金属单一及复合污染下，黑麦草幼苗的根、茎、叶的电阻抗图谱参数，重金属含量（包括全量、不同提取态及不同亚细胞组分的金属含量）及表征其生态毒性的生理参数，包括抗氧化酶活性（SOD、POD、CAT）、相对电导率、含水率，丙二醛、可溶性蛋白和可溶性糖的含量，并对样品作电镜分析。试图发现在铜、镉、铅等重金属离子的单一及复合污染下，黑麦草根、茎、叶电阻抗图谱参数的变化规律以及与生理参数的关系，试图找到黑麦草的电阻抗图谱参数与重金属含量的剂量效应关系，应用电阻抗图谱参数指示重金属离子的毒性效应；通过电阻抗图谱参数进一部诊断水体或土壤中重金属离子的污染程度。并对电阻抗图谱参数对重金属污染的响应原因进行微观机理解释。

本项目通过对大豆在Cd2+、Cu2+和Zn2+单一及复合胁迫下的电阻抗参数变化及其对重金属浓度曲线的拟合计算得到大豆在不同胁迫下的耐受阈值，试图寻找一种快速筛选高耐性重金属植物的方法，该方法简便快速易操作。在上述3种离子单一胁迫的3天和7天，由电阻抗参数计算得到的耐受阈值对Cd2+、Cu2+和Zn2+分别为272.27 mg/L和91.03 mg/L，41.29mg/L和27.92 mg/L，536.04mg/L和511.81mg/L，与相对电导率计算得到的值比较接近。此外，大豆对3种离子的耐受阈值表现为Zn>Cd>Cu，且随着时间增加，耐受阈值减小。复合污染的耐受阈值表现为Cd(主元素)-Cu>Cd，Cu(主元素)-Cd>Cu，Cd(主元素)-Zn>Cd，Zn(主元素)-Cd< Zn，Cu(主元素)-Zn>Cu，Zn(主元素)-Cu<Zn，说明Cd、Cu之间具有拮抗作用；Cd、Zn复合污染对Zn表现为协同作用，对Cd表现为拮抗作用；Cu、Zn复合污染对Zn表现为协同作用，对Cu表现为拮抗作用，Cu对Zn耐受阈值的影响较Zn对Cu的影响要大。