【作者】 谢华；

【导师】 林鉴钊； 陈同斌；

【作者基本信息】 广西大学 ， 作物耕作学与栽培学， 2004， 硕士

【摘要】 砷污染问题已引起世界各国的密切关注。土壤中的砷可通过食物链途径进入人体，还可由飘尘、淋失等造成大气和水体的二次污染。常规土壤治理方法不能经济有效地修复砷污染土壤，应用砷超富集植物蜈蚣草对砷污染土壤进行植物修复是被认为是经济、快速、无二次污染的新方法。本文调查湖南郴州市的典型砷污染区农田中植物砷浓度，评估其健康风险及危害途径，结合进行砷超富集植物的微观结构及形态特征变化研究，试图筛选适合于砷污染农田修复的植物种类(居群)。本文研究结果表明： 1．土壤砷污染程度对抛荒农田自然恢复植被类型有显著影响，恶性杂草雀稗是自然恢复植被物种丰富度的直接控制因子。当地蔬菜可食部位的砷浓度超标现象严重。人体通过蔬菜途径摄入的砷量超过了WHO限定的安全标准(每日2.1 μg／kg体重)。砷的摄入途径分析发现，自然恢复植被和种植污染区域的蔬菜都是当地居民砷暴露的重要途径。 2．在砷污染农田上进行不同种类植物的小区对比试验表明，超富集植物蜈蚣草适于修复农田砷污染。耐性植物五节芒和苎麻对污染农田的修复效率为蜈蚣草的四百至六百分之一，不适用于修复砷污染农田。工业用经济作物蓖麻的生物积累砷量最小，而且产量很低。 3．对不同地区蜈蚣草体细胞染色体倍性的初步分析表明，各地区硕士学位论文砷超富集植物的超微结构、形态特征及其植物修复效果娱蚁草倍性有差异，不同倍性螟蛤草对砷的总富集量为:二倍体>三倍体>四倍体。不同浓度砷处理对娱蚁草袍子的萌发和配子体的发育有显著影响:低浓度砷起促进作用，高浓度砷起抑制作用，且抑制作用随砷浓度升高而增强。 4.对砷、钙处理下叶片细胞的超微结构变化研究表明:娱蚁草对砷、钙具有较强的耐受能力，过高浓度的钙使娱蚁草叶绿体结构受到一定程度的破坏。介质中钙的适量增加可缓解砷对大叶井口边草叶绿体和线粒体的胁迫。大叶井口边草对缺钙的敏感程度较高。对细胞中Caz+分布研究表明:高钙处理对娱蚁草产生逆境胁迫;高砷胁迫下，娱蚁草可自主协调适应。钙和大叶井口边草对砷的解毒作用可能有关。更多还原

【Abstract】 Arsenic contamination and exposure, because of its toxicity ,and carcinogenicity, caused great concern. However, the hazard of soil arsenic contamination, which usually fails to notice and consider, has not became an important environmental issue. Conventional technology has not adapted to remediated arsenic contaminated soil effectively and economically. Phytoremediation of As-contaminated soils with arsenic hypteraccumulator - Pteris vittata L. has been considered to be an economic, fast and little secondary contaminative new remedial technology. In order to pick out the right plants (groups) which can be apply to phytoremediation of As-contaminated farmlands, arsenic in plants and potential risk for human from As-contaminated farmlands in Chenzhou city, Hunan province were assessed, and ultrastructure and morphological character change of arsenic hyperaccumulators after arsenic treatment have been researched.1.Revegetation in As-contaminated soil was significantly affected by contaminated grade, The main factor for controlling the species diversity in the soil was growth of Paspalum sp., a dominated weed. As concentration in edible part of most vegetables exceed the maximal permissible limit. Intake of arsenic from consuming vegetables exceeded the standard (2.1 ng/kg body wt. per day) set by WHO.2.Comparative test of four different plants on As-contaminated farmland, the results showed: hyperaccumulator - P. vittata is the one which adapt to apply to phytoremediation; both remedial efficiency of tolerant plants Miscanthus floridulu Warb. and Boehmeria nivea (L.) Gaud, far lower than P. vittata’s, so these two kinds tolerant plants are not fit to apply to phytoremediation; arsenic biotic pyramid of the industrial commercial crop Ricinus communis L. is the lowest one ,and it’s crop outputwas very low.3.Ploidies of P. vittata come from three areas have been analyzed, and the results show that they are different. As-accumulate capability trend of different ploidy is: diploid>triploid>tetraploid. Growth and development of P. vittata’s gametophyte was significantly affected by arsenic concentration: they can be promoted by the low concentration and be inhibited by high concentration, and the inhibition can be strengthening by lifting of arsenic concentration.4.Ultrastructure character change of leaf after different arsenic and calcium concentration treatment have been research, the results show that structure of P. vittata’s chloroplast can be damaged by the high calcium concentration, and P. vittata have the high tolerance to arsenic and calcium. Add proper quantities calcium can lighten arsenic menace to chloroplast and mitochondria of Pteris nevosa. Research of the Ca2+ distribution in cell show that high concentration calcium makes menace to P. vittata, which can adjust itself under high arsenic menace. Calcium maybe related to the arsenic antidotal action of P. nevosa.更多还原