【作者】 王美娥；

【导师】 周启星；

【作者基本信息】 中国科学院研究生院（沈阳应用生态研究所） ， 生态学， 2006， 博士

【摘要】 豆磺隆在土壤中残效期较长,易对后茬敏感作物以及周围敏感植物物种产生药害,造成农业生态环境污染,危害区域性陆地生态系统完整性。化肥和其它农药的使用,带入了重金属如:铜、镉、铅和锌等,导致豆磺隆和重金属的复合污染的发生。本研究所得参数不仅为豆磺隆-重金属复合污染的生态风险评价提供了一定的理论依据,还为诊断豆磺隆-重金属复合污染提供了快捷有效的生物标记物。低浓度豆磺隆、Cu、Cd复合时,豆磺隆与重金属对根长抑制率具有拮抗作用;当Cu、Cd浓度较高时,豆磺隆与重金属对小麦幼苗芽长、根长的抑制率具有显著的协同作用(P<0.05);同时,复合污染的联合毒性更多的倾向于重金属的毒性。作为可见症状之一,叶绿素下降只在豆磺隆、Cd单一处理时表现出来,复合处理时由于有机物与重金属的相互作用抵消了两者对叶片叶绿素含量的影响。酶活变化与可溶性蛋白质含量的变化有一定的相关性,但是可溶性蛋白质的变化主要还是由于污染物抑制植物体生长,抑制蛋白质生物合成的性质有关。污染物的化学性质决定其对生物体的毒性机制以及在复合污染时的联合效应;有机物、重金属单一处理之间以及两者与有机物-重金属复合处理之间的毒性机理有明显的不同。但是正如不同重金属之间的毒性机理有一定共性一样,不同重金属和有机物的联合毒性机理也有一定的共性。豆磺隆-重金属对小麦幼苗生化水平上的联合效应随着不同的浓度组合以及不同的植物部位而不同。小麦幼苗根系POD、SOD酶活以及SP含量的下降可以被用来作为指示除草剂以及重金属胁迫的生物指示物。Cd比豆磺隆单因子以及豆磺隆-Cd复合处理更容易对DNA分子产生伤害。一定浓度组合的豆磺隆-Cd复合处理下,豆磺隆能够减轻Cd对DNA分子的毒性。引物序列的不同对污染物的敏感性也不同。豆磺隆、Cd引起的损伤可能发生在DNA序列上的特定位置。单因子和复合处理对新条带出现有不同的敏感性,这可能是因为豆磺隆和Cd的交互作用降低了引物S1156位点上的DNA变化概率。更多还原

【Abstract】 The residual of chlorimuron-ethyl has adverse effects on sensitive crops and other plant species all around even long after spraying. So its prolonged and wide use will lead to territorially agroecological pollution and eventually cause the loss of agroecological integrity. Meanwhile, the use of fertilizers and pestcides will input heavy metals such as Cd, Cu, Pb and Zn, which will lead to the combined pollution of chlorimuron-ethyl and heavy metals. The results of this study could be considered as the base for the ecological risk assessment of combined pollution of chlorimuron-ethyl and heavy metals. And sensitive biomarkers have been screened in this work for the diagnosis of the joint stress of chlorimuron-ethyl and heavy metals.When chlorimuron-ethyl and heavy metals are combined with low concentrations, chlorimuron-ethyl and heavy metals have antagonistic effect on the root elongation of wheat seedlings. However, when the concentrations of chlorimuron-ethyl and heavy metals are high, chlorimuron-ethyl and heavy metals have significantly synergistic effects on the shoot and root elongation of wheat seedlings. Meanwhile, the joint effects were more depended on the effects of heavy metals than on those of chlorimuron-ethyl.As one of the visible symptoms, the obvious decrease of chlorophyll content in wheat seedlings only was detected under single stress of chlorimuron-ethyl and Cd. With combined stresses of chlorimuron-ethyl and heavy metals, the toxic effects of the two chemicals on chlorophyll content were alleviated by the antagonistic action of chlorimuron-ethyl and heavy metals. The change of antioxidant enzyme activities was correlated with the change of soluble protein content. However, the alteration of soluble protein content was caused mainly by the toxic chemicals due to their inhibition of protein biosynthesis. The chemical property of pollutants determined the toxic mechanisms to plants and the joint effects of the combined pollution. There were significant difference in the toxic mechanisms between chlorimuron-ethyl and heavy metals as well as between single stress of chlorimuron-ethyl and heavy metals and combined stress of chlorimuron-ethyl-heavy metal. However, there existed common toxic mechanisms between combined treatments of chlorimuron-ethyl-Cd and chlorimuron-ethyl-Cu as well as between single stress of Cd and Cu. And the join effects of chlorimuron-ethyl and heavy metals on wheat seedlings at the biochemical level altered among different concentration combination of the two chemicals as well as among different action tissues of plants. The decrease of POD and SOD activities and SP content in wheat roots could be considered biomarkers indicating the stress of chlorimuron-ethyl and heavy metal.Single stress of Cd had more toxicity to DNA than single stress of chlorimuron-ethyl and joint stress of chlorimuron-ethyl and Cd. When treated with special concentration combination of chlorimuron-ethyl and Cd, chlorimuron-ethyl would decrease the toxicity of Cd to DNA. The sensivity to pollutants would alter with different sequence of primers. The damage caused by chlorimuron-ethyl and Cd might be taken place at the special sites of DNA sequence. There were different appearance frequency of new bands between single and joint stress of Cd and chlorimuron-ethyl, which might be due to the decrease of the change rate in DNA sequence at the primer S1156 site caused by the transaction of chlorimuron-ethyl and Cd.更多还原