【作者】 李廷强；

【导师】 杨肖娥；

【作者基本信息】 浙江大学 ， 植物营养学， 2005， 博士

【摘要】 植物修复技术因其高效低耗、保持水土和美化环境等特点,已引起国际土壤——植物营养学界和环境科学界的浓厚兴趣和政府部门的高度重视,有望成为一项具有广阔应用前景的治理重金属污染土壤的全新技术。而目前对植物超积累重金属机理认识的不足限制了该技术的应用和改良。东南景天（Sedum alfredii Hance）是在我国东南部地区一些古老的铅锌矿上发现的一种新的锌镉超积累植物,同时对铅具有富积作用。本研究以超积累植物东南景天为材料,采用水培和土培的方法,运用同位素示踪技术、高效液相色谱分析技术、原子吸收光谱技术等,较系统地研究了超积累生态型东南景天活化、吸收、转运重金属的机制,取得的主要研究结果如下: 1.东南景天能增加根系与土壤的接触面积,提高对重金属的吸收。1000μmol L^-1Zn、200μmol L^-1Pb和200/1000μmol L^-1Pb/Zn复合处理对东南景天根系形态的影响因不同生态型而异,其中对根系长度、根系表面积、根系体积的影响较大,而对根系直径影响较小,差异不显著。1000μmol L^-1Zn和200/1000μmol L^-1Pb/Zn复合处理对超积累生态型东南景天根系生长有明显的促进作用,200μmol L^-1Pb、1000μmolL^-1Zn和Pb/Zn复合处理对非超积累生态型根系生长表现出明显的抑制作用。1000μmol L^-1Zn和Pb/Zn复合处理对超积累生态型东南景天根系活力没有显著影响,非超积累生态型东南景天在各处理条件下根系活力显著降低,且随着处理时间的增加没有回升。东南景天根长、根表面积、根体积与体内Pb、Zn含量呈显著或极显著正相关。也就说,超积累生态型东南景天的根长、根表面积、根体积明显大于非超积累生态型,可通过增加根长、根体积和侧根数量以增加根系与土壤的接触面积,从而提高根系对锌、铅的吸收机会,因而其体内Pb、Zn含量高。 2.50-500μmol L^-1Zn处理条件下,非超积累生态型东南景天根系生长受到抑制,而500μmol L^-1Zn处理后超积累生态型的根系干重明显增加。Zn对超积累生态型东南景天根系活力没有显著的影响,而对非超积累生态型,当Zn浓度大于10μmol L^-1,根系活力明显降低。随着锌浓度的增加,非超积累生态型东南景天根系膜透性、MDA含量显著增大,锌对细胞膜结构造成了很大的危害。Zn>50μmol L^-1使非超积累生态型东南景天SOD活性显著降低。超积累生态型东南景天根系膜透性、MDA含量、SOD酶活性、脯氨酸含量与地上部及根系锌含量相关性不显著。非超积累生态型东南景天根系活力、SOD酶活性与地上部及根系锌含量呈显著或极显著负相关,而MDA含量、脯氨酸含量与地上部及根系锌含量呈显著正相关。超积累生态型东南景天比非超积累生态型具有更强的忍耐溶液锌的能力,在同等锌浓度下,其根系生理活性高于非超积累生态型。 3.种植超积累生态型东南景天后,根际土壤pH值较非根际土壤减低0.3个单位,更多还原

【Abstract】 Phytoremediation is defined as the use of plants to decontaminate and/or remove pollutants from the environment. It has emerged as an alternative technique for removing toxic metals from soil and offers the benefits of being in situ, cost-effective and environmentally sustainable Plants with high metal uptake and accumulation capacity have been termed as hyperaccumulator species. At present, more than 450 species of hyperaccumulators belonging to 45 families have been identified. Unfortunately, most of them are low biomass and slow growing, severely limiting their potential for large-scale decontamination of polluted soils. Transferring the genes conferring the hyperaccumulating phenotype to plants that produce more shoot biomass and metal accumulation capacity has been suggested as a potential approach for making phytoremediation a viable commercial technology. However, progress towards this goal has been hindered by a lack of understanding of the basic biochemical, physiological, and molecular mechanisms involved in heavy metal hyperaccumulationSedum aljredii Hance has been identified as a new Zn-hyperaccumulating plant species native to China. We have found two contrasting ecotypes of Sedum aljredii Hance. One is a Zn/Cd hyperaccumulator designatured as the hyperaccumulating ecotype （HE） from the old mined area, while another is a non-hyperaccumulator designatured as non-hyperaccumulating ecotype （NHE） from the agricultural area of Hangzhou surburb, Zhejiang Province of China. In this study, solution culture experiment, soil culture experiment and simulation experiment were carried out to characterize Zn activation, uptake and transport in Sedum aljredii Hance by means of a series of chemical, biochemical methods, such as radiotracer techniques, AAS for elements determination, organic acid quantitation determined with HPLC, and so on. The major results were summarized as follows:1. Heavy metal uptake was enhanced in hyperaccumulator ecotype of Sedum aljredii Hance by increasing the contact area between soot and soil. Root length, root surface-area and root volume increased obviously due to 1000 umol L^-1 Zn and/or 200/500 umol L^-1 Pb/Zn combined treatments for the HE, whereas significantly decreased due to 200 μmol L^-1Pb, 1000 μmol L^-1Zn or Pb/Zn combined treatment for the NHE. Zinc and Pb concentrations in both ecotypes of Sedum aljredii Hance were positively correlated with root length, root surface area and root volume 1000 μmol L^-1Zn and/or 200/1000 umol L^-1 Pb/Zn combined treatments had little impact on root activity of the HE. Root activity of HE decreased by 200 umol L^-1 Pb treatment in the first 2 days, but recovered afterwardsand close to the control at day 10 of the treatment. However, root activity of the NHE decreased by each metal treatment, and was not recovered with the advance of treatment time. Zn concentrations in the leaves and stems of the HE were 41 and 34 times higher, whereas lead concentrations were 1.9 and 2.4 times greater respectively, than those of the NHE when grown at 1000 μmol L^-1 Zn and/or 100 μmol L^-1 Pb. At combined supply of 500/100 μmol L^-1 Zn/Pb, however, zinc concentrations in the stems and leaves of the HE decreased, while lead concentrations in the stems increased significantly, as compared with those of single metal treatment. Lead uptake of the HE was enhanced by Zn addition.2. Zn treatments had little impact on root activity of the HE, however, root activity of NHE decreased significantly when Zn concentration > 10 μmol L^-1. Relatively conductance ratio of cell membrane and MDA concentration in NHE increased with increasing of Zn level in the solution. SOD activity of NHE was decreased significantly when Zn concentration > 50 μmol L^-1. Cell membrane, MDA concentration, SOD activity, and proline concentration in root of HE were not correlated with Zn concentration in shoot and root of HE. Minimal linear relationships between root activity, SOD activity and Zn concentration in shoot and root of NHE were observed, however, MDA and pro更多还原