【作者】 姜理英；

【导师】 杨肖娥；

【作者基本信息】 浙江大学 ， 植物营养学， 2003， 博士

【摘要】 重金属污染环境植物修复研究是近几年国内外环境治理的热点和前沿领域，它利用某些耐性或超积累植物能从土壤中超量吸收转移一种或几种重金属的特性，从而达到减少土壤中重金属含量之目的。铜污染土壤的植物修复机理远未清楚，因此，研究不同植物对铜耐性和吸收特性及其在污染土壤修复中应用技术基础，对丰富植物修复理论，保障我国环境生态健康都具有重要意义。本论文结合野外调查、水培和土培等一系列培养方法，研究了两种香薷植物—海州香薷（E.splendens）和紫花香薷（E.argyi）对介质中铜的耐性及其对铜的吸收、运输和分布特性，并在对浙江省富阳市环山乡某一重金属典型污染地区调查的基础上，开展了田间试验研究这两种香薷对重金属污染土壤的植物修复潜力及其调控因素。主要研究结果归纳如下： 1． 对浙江省富阳市污染比较严重的一个小高炉周围农田的土壤进行了调查分析，发现该区土壤的重金属污染主要是As、Cd、Cu、Pb和Zn这5种元素，尤其是Cu、Pb、Zn的含量分别可达1775.6、1140.1和621.3 mg kg^-1。在土壤重金属水平分布方向上，土壤受其污染的程度随污染源距离的增加而降低，到300m处已基本没有影响，在土壤重金属垂直分布方向上，其对土壤表层污染较为严重，并发现土壤微生物碳量与土壤重金属的含量有显著的负相关。在大田中采取的一些农艺措施降低重金属对作物的生长的影响，表明施石灰等农艺措施虽然降低了土壤中有效重金属含量并提高了产量，但未能使水稻谷粒内的重金属含量达到国家卫生标准。这些结果表明，农业土壤受重金属污染对人类健康具有潜在威胁，需要进行绿色修复，恢复或重建健康生态系统。 2． 对浙江省诸暨铜矿山和三门Pb／Zn矿进行系统的调查，发现诸暨铜矿的矿床主要分布在海拔630m左右，海州香薷是铜矿床及尾矿渣上生长的优势植物，其不仅能在全铜和醋酸铵提取态铜含量分别高达6050和665mg kg^-1的土壤上正常生长，而且能在废矿渣堆（水分和养分较贫乏）条件下大量生长，对土壤中的高铜和养分条件都具有较好的耐性。此外发现，紫花香薷是三门Pb／Zn的主要优势植物，其能在NH₄OAc-Zn和NH₄OAc-Pb含量都高于100mg kg^-1的土壤上正常生长，而且其生物量都高于海州香薷。因此，可以得出海州香薷和矿山生态型紫花香薷对重金属都具有较高耐性。 3． 在三门铅锌矿山上植物调查中找到了生物量大于海州香薷的紫花香薷，同时在杭州也发现非矿山生态型的紫花香薷。通过研究这两种生态型对Cu水平的生长反应以及铜吸收、运输和分布的差异。结果表明，矿山生态型比非矿山生态型具有更强的耐高Cu的能力。非矿山生态型根系和叶片的生物量在Cu处理水平为10μmol L-1时显著减少，而矿山生态型在50μmol L-1 Cu处理时才明显减少。矿山生态型根系Cu含量高于非矿山生态型，但地上部分，尤其是茎部Cu含量却低于非矿山生态型。此外，Cu从根系向地上部分的运输速率以及茎／根Cu含量与叶／根Cu含量比值也是非矿山生态型大于矿山生态型。这表明矿山生态型紫花香蕉是一种耐Cll植物，主要与其限制Cu从根部向地上部运输有关。4．通过水培试验研究海州香蕉和紫花香蕾对＊u的吸收、分配和积累的差异，发现高CU（主78 pm＊“‘）对两种香蕉的株高、根系伸长和地上部分及根系的干物质产量都有抑制作用，但海州香蕾受抑的程度较紫花香蕾小。在铜供应水平为625和1250 pm＊厂’条件下，海州香蕉和紫花香蓄地上部分＊u含量分别超过1000＊g吨’‘，并且海州香蓄地上部分／根系＊u含量的比值大于紫花香蕾，而且＊u在植物地上部分的分配比率以及Cu从根系向地上部分的运输速率都高于紫花香素。在Cu处理12天时海州香蕾和紫花香蕉地上部分的最大＊u积累量可分别高达101和142pg株1。因此从本研究可以看出海州香蕾和紫花香需在＊u污染土壤植物修复中都具有良好的应用潜力。5．植物对铜的耐性和吸收可能受锌等其它阳离子的供应的调节。通过水培试验研究Cu和 Zn处理对两种香蕉生长及 Cu、Zn吸收和积累的影响。研究结果表明，50 polL‘的＊u有利于海州香需根系的生长，但却明显抑制紫花香蓄地上部分的干物质产量，Zn处理浓度直到 200 pmolL’也未见两种香蕉的干物质产量的下降。而且两种香蕉地上部分 Cu含量和积累量无论是高Cu还是低 Cu时都随 Zn的增加而减少。而海州香蓄地上部分的＊n含量却随着＊u处理水平的增加而有不同程度的提高，表现为Cu促进Zn的在体内的运输。同样紫花香需在Zn供应水平为 0．5和 50pmol’时，＊u的增加也促进了＊n的运输。而且海州香需在高＊u＊00 p＊厂’对高＊nQ00 pmOIL’)时对 Cu和 Zn的积累量明显高于紫花香需。6．对海州香慧和紫花香蕾在重金属污染土壤的植物修复效应研究，表明这两种香曹植物都能在铜等严重污染的农业土壤（全Cu量为320刁440mgkg－1）中正常生长，虽然在土壤全 Cu为 1200 mg kg”时地上部干物质产量略有下降，但也高达 9 ton ha”’以上。对＊u的吸收和积累特性的研究，表明海州香蕾和紫花香蕾对土壤中铜的吸收和地上部浓度生育前期明显高于生育后期，在收获期?更多还原

【Abstract】 Phytoremediation is a new novel technique to clean up contaminated soils with some accumulators or hyperaccumulators which can take up heavy metal, and transport and accumulation them in their above ground shoots. The mechanisms of phytoremediation for Cu contaminated soils are not fully understood and the technology is not established yet. Therefore, it is importance to elucidate the characteristics of Cu tolerance and uptake by specialized plants, and the mechanisms of phytoremediation of Cu polluted soils. The major objectives of this study were to identify Cu tolerant and accumulating plant species and characterize their Cu uptake and tolerance, understand their potential of application to phytoremediation of the Cu contaminated agricultural soil, as well as the factors enhancing phytoremediation efficiency. The main results obtained were summarized as follows:1. Investigation and analysis of soils and plants in the heavily polluted agricultural field near a smelting factory showed that the main contaminated heavy metals included As, Cd, Cu, Pb and Zn, among which Cu, Pb and Zn content in soil were very high, reached 1775.6, 1140.1 and 621.3 mg kg"1 respectively. The metal content in the soil decreased with increasing distance from the smelting factory and reached normal level at a distance of about 300 m. Heavy metal concentrations were relatively high at the surface soil layer (15cm), and decreased with increasing soil depth. Soil microbial carbon content in surface soil was closely related to the soil heavy-metal. Some agricultural measures were adopted in a field experiment to remediate the polluted soil, and they effectively reduced available heavy metal content in the soil and increased the crop yield. Yet, the heavy metal concentrations in rice grains still failed to achieve the national sanitary standards. These results indicate that normal chemical amendments can reduced metal toxicity of the crop plants, but can’t ensure crop food safety and ecosystem safety.2. Detailed field survey on Cu mining area in Zhuji and Pb/Zn mining area in Sanmeng of Zhejiang province. The results showed that the Cu ore deposit in Zhuji mostly at the altitude of about 630 m and E. splendens was the dominant plants speciesgrowing on Cu ore deposit, and its distribution is along with that of the Cu ore deposit. Chemical analysis indicated that that E. splendens grew prosperously in soil which total Cu and NH4OAc-extracted Cu up to 6050 and 665 mg kg-1 respectively, and in mined tails with both low water and nutrient supply. Copper concentration in root and shoot of E. splendens was 223-613 mg kg-1 and 23-91 mg kg-1. In Sanmeng mining area, E. argyi was the dominant plant species, which grow normally in soil which NH4OAc-extracted Pb and Zn was more than 1000 mg kg-1. Hence, it is concluded that E. splendens and E. argyi belong to Cu tolerant plants in most cases.3. One non-mined ecotype of Elsholtzia argyi was found in Hangzhou suburb. Two contrasting ecotypes of E. argyi were compared with nutrient solution culture for their growth response and the uptake, distribution, and translocation of Cu. The results showed that the ecotype from the old mined area (Sanmen-ecotype) had greater tolerance of Cu than that from the non-mined area (Jiuxi-ecotype) based on their dry matter production. Inhibition of root and leaf growth was noted at the external Cu levels > 50 umol L"1 for the Sanmen-ecotype, and at > 5 umol L"1 Cu for the Jiuxi-ecotype respectively. Root Cu concentrations were higher in Sanmen-ecotype than in Jiuxi-ecotype, by contrast, leafespecially stem Cu concentrations were much lower in the former than in the latter. Furthermore, Jiuxi-ecotype was much more efficient than Sanmeng-ecotype in translocation of Cu from root to shoot, and it had higher ratios of stem/root and leaf/root Cu concentration. These results indicate that the Sanmen-ecotype of E. argyi is a Cu-tolerant ecotype, and its tolerance to high Cu levels was mainly related to its extraordinary capab更多还原