【作者】 蔡保松；

【导师】 张国平； 陈同斌；

【作者基本信息】 浙江大学 ， 作物学， 2004， 博士

【摘要】 植物修复技术是一种利用超富集植物提取污染土壤中有害物质的技术。超富集植物能够将吸收的重金属大部分运输到地上部，人们通过收集地上部并进行适当处理从而减少污染土壤中的重金属含量，使之达到清洁安全。植物修复是一种价格低廉、易于工业化和环境友好的技术，有非常广阔的应用前景。 蜈蚣草是最近发现的砷超富集植物，具有生长快、适应性广和吸收积累砷能力强等特点，是一种理想的砷超富集植物，而我国蜈蚣草野生资源丰富。研究表明，不同地域生长的蜈蚣草外形指标和砷富集能力存在着很大的差异；另外，一些外源物质也影响蜈蚣草对砷的吸收，添加外源物质是提高蜈蚣草砷污染土壤修复效率的一个有效措施。然而，有关蜈蚣草富集砷能力的基因型差异尚未有过系统研究。 本研究首先调查了湖南砷污染区的植物生长环境，发现砷污染已导致植物种类减少，群体生物量下降；污染区栽培的蔬菜有54％砷含量超标，其中菠菜、茼蒿和莴笋等超过最大许可量(MPC)的5倍左右。因此，这些地区的砷污染对人们的饮食健康构成了巨大威胁。 不同基因型的蜈蚣草的直接播种试验研究表明，来自我国不同地区的蜈蚣草基因型在萌发特性有显著差异，萌发时间变动在12-40 d之间，萌发到成苗时间变化在13-46d。因为蜈蚣草种子小，贮藏的营养物质少，故具有快速萌发和成苗特性的基因型易于田间直接育苗。根据研究结果，我们筛选到3、4、5、9、13和15号等6个野外育苗比较容易成功的基因型。 研究了分布于我国不同地区的蜈蚣草基因型的生长特性、砷耐性和富集特性，结果显示：蜈蚣草基因型间株高、羽叶数、芽苞数、地上部鲜重、根部鲜重均有显著的差异，株高变化在29.6-68.2 cm，羽叶数变化在13.3-60.0个／株，芽苞数变化在9.0-65.7个／株，地上部和地下部鲜重分别变化在150—540克／株和20.3-94.9克／株。蜈蚣草基因型间砷富集量差异明显，供试基因型的地上部砷浓度变幅在643.1—3009.03mg／kg，地下部变动在44.4-112.4 mg／kg；地上部砷积累量变化在49.7-174.7 mg／株，地下部在0.48-2.84 mg／株：富集系数(BF)变化在17.2-81.9，转运系数(TF)变化在10.8-50.4。蜈蚣草基因型在生物性状和砷富集特性上的广泛差异启示出，通过筛选可中文摘要以获得砷富集能力强、植株根系扩展范围大的基因型，从而提高植物修复效率。 娱蛤草对砷的耐性是决定修复范围的一个重要因素，耐性越强，利用娱蛤草修复的范围越大。对娱蛤草不同基因型砷耐性的研究显示，娱蛤草对砷的耐性较强，远大于目前报道的其它砷耐性植物;耐性不同的娱蛤草基因型在富集砷的能力上也存在显著的差异，高耐性基因型根吸收砷的总量小于低耐性基因型，相反，向地上部运输的能力则大于低耐性基因型。由于高耐性基因型的砷总吸收量显著少于低耐性基因型，最终表现为地上部砷积累量明显较少。回归分析表明，娱蛤草对砷的耐性和对砷的富集特性呈反比。因此，为了提高娱蛤草植物的修复效率，在植物修复实践中应选择砷耐性相对较低的娱蛤草基因型，同时砷耐性可以作为娱蛤草砷富集特性的田间鉴定指标。 砷污染修复的目标环境一般土壤贫瘩，从而限制娱蛤草的生长和对砷吸收及积累的能力。因此，开发利用廉价、有效的肥源是植物修复过程中重要的一环。同时土壤水分状况与植物生长发育以及砷的有效性关系密切。研究土壤水分状况与娱蛤草生物量积累及砷吸收的关系发现，在极度干早(土壤含水量40%)情况下，娱蛤草地上部的砷浓度虽然很高，但由于生物量较小，修复效果不好;反之，土壤水分过多(土壤含量水高于80%)，娱蛤草生长也不好;在50一60%的土壤水分范围内，娱蛤草地上部砷浓度虽较低，但由于生物量大，砷富集量也大，因此这是植物修复实践中最佳的土壤含水量。水分对娱蛤草富集砷的影响是通过影响娱蛤草的吸收功能实现的，研究表明，随着土壤水分含量的提高，土壤中可交换砷和可溶性砷含量增加。在种植有娱蛤草的情况下，当土壤含水量为50一60%时，土壤可交换性砷和可溶性砷浓度最小，说明此时娱蛤草对砷有最大的吸收:水分也影响砷的淋溶性，在50一60%水分含量下，种植有娱蛤草的土壤砷淋溶最小。 堆肥是城市固体废弃物经过脱水、发酵、除臭加工制成的肥料，堆肥中含有丰富的有机物和微生物，堆肥的资源化利用是解决城市固体废弃物的一个重要方面。磷石膏是磷肥生产过程中产生的主要副产物，每生产1吨磷肥产生3吨磷石膏，磷石膏含有磷和钙。鉴此，我们研究了植物修复实践上是否可以利用堆肥和磷石膏作为肥源，从而达到以污治污的目的。结果证明，堆肥和磷石膏能够显著增加娱蛤草的株高和生物量:堆肥增加土壤中可溶性有机碳(DOC)和可溶性砷含量，从而促进娱蛤草对砷的吸收;磷石膏也具有增加土壤中可溶性砷的含量和促进娱蛤草对砷的富集作用。 对娱蛤草的超富集机理研究证实，植物鳌合肤(PC)参与娱蛤草富集砷的过程。乙 博士论文:娱蛤草富集砷能力的基因型差异及其对环境因子的反应在砷胁迫环境中，娱蛤草地上部PC更多还原

【Abstract】 Phytoremediation is a special technoloque of remediating contaminated soil by using the plant hyperaccumulators to remove pollutants in soil. The hyperaccumulators has the great capacity of absorbing heavy metals from soil and transporting most of them into the above-ground parts, which are then harvested artificially and dealt with properly, making a dramatic reduction of heavy metal content in soil. It is commonly recognized that phytoremediation is a cost-effective, engineering-economical and environmental friendly technique, and shows great prospect in the practice of contaminated soil remediation.Pteris vittata is a newly discovered As-hyperaccumulator, and has been identified as a reasonable material for use in phytoremediation of As-contaminated soil. There are abundant germplasm of Pteris vittata in China It is shown in the field investigations that there exists a large variation in morphology and growth characterizations, and As-acumulating ability among Pteris vittata genotypes, inhabited in the different ecological zone of China. It is also demonstrated in the field trials that some exotic substance have substantial influence on As uptaking by Pteris vittata, indicating the significance of applying proper chemicals into the soil to be remidiated in improving remediation efficiency. However, little research has been done in study on the genotypic difference of Pteris vittata in As-accumulating ability.In a survey aiming at making clear of the environmental conditions of plants in the As-contaminated areas in Hunan Province, it is found that As-contamination has caused a marked decrease in plant species and reduction in biomass of the plants grown there. Moreever, there is higher than 54% of cultivated vegetables with As content beyond the critical value of safety for food. Of them, spinach, crown daisy and lettuce are particularly severe in terms of their As content, being 5 fold as high as Maximum Permitted Concentration (MPC) based on Chinese Stardard of Vegetable Sanitation. It may be concluded that As-contamination in the soils of these areas has posed the great threat to human health.The direct seeding experiments of different Pteris vittata genotypes showed that there was significant difference in germination and emergence traits among Pteris vittata genotypes collected from different areas in China, with germinating time ranging from 12-40days, duration from germination to emergence varying between 13-46 days. As the seeds of Pteris vittata are very small, with little stored nutrition, the genotypes, which are quick in germination and emergence, are suitable for direct seeding in the field. According to the results, 6 genotypes, coded as No. 3, 4, 5, 9, 13 and 15, are scrrened out for their more probability in success of directly seeding in field.The growth traits, As-tolerance and bioaccumulation of different Pteris vittata genotypes, which were collected from different areas of China, were studied. The result showed that there was a remarkable difference in plant height, number of frond and sprout, fresh weight of above-ground parts and roots among different genotypes. Plant height varied from 29.6 to 68.2 cm, frond from 13.3 to 60.0 per plant and sprout from 9.0 to 65.7 per plant, fresh weight of aboveground parts and soil ranged from 150 to 540 g and from 20.3 to 94.9 g per plant, respectively. Meanwhile, the significant difference was also noted in As concentration and accumulation in plants among Pteris vittata genotypes. The As concentration in aboveground parts and roots ranged from 643.1 to 3009.03 mg/kg, and from 44.4 to 112.4 mg/kg, respectively. Correspondingly, As accumulation in aboveground and roots ranged from 49.7 to 174.7 mg per plant and from 0.48 to 2.84 mg per plant, respectively. Bioaccumulation factors (BF) varied from 17.2-81.9 and transport factors (TF) from 10.8-50.4. The wide difference in biological traits and As-accumulating ability among Pteris vittata genotypes illuminated that it is possible to develop the Pteris vittata genotypes with higher As-bio更多还原