【作者】 朱小娇；

【导师】 黄巧云；

【作者基本信息】 华中农业大学 ， 土壤学， 2010， 硕士

【摘要】 由于重金属污染物的高毒和排放量的日益增加,土壤重金属修复问题引起了人们广泛的关注。土壤重金属可被植物吸收从而通过食物链危害人体健康。本试验以不同浓度Cd(0、1、2、4 mg kg-1干土)处理的武汉市狮子山棕红壤为材料,采用小麦盆栽实验评价草木灰和对Cd具有高吸附力的工程菌固定土壤Cd和降低其生物毒性的效果。获得的主要结果如下：1.Cd污染土壤中,接种基因工程菌对土壤pH值和酶活性没有显著影响；当土壤中施用10 g kg-1干土草木灰时,土壤pH值上升0.83～1.01个单位,土壤蔗糖酶、脲酶和过氧化氢酶活性升高,最高增加4.13倍,土壤磷酸酶活性降低了8.18～49.94%。2.Cd污染土壤中,当施入草木灰和工程菌后,土壤中的Cd重新分配。草木灰有利于促使土壤中水溶态／交换态Cd向无机结合态转化。在所有草木灰和菌体处理的土壤中,超过86.1%的Cd集中在水溶态／交换态和无机结合态,未添加草木灰的3种处理土壤中51.6-59.6%的Cd以水溶态／交换态形式存在,添加了草木灰后土壤中水溶态／交换态Cd仅占土壤Cd总量的14.68～21.14%,而69.9～82.4%的Cd以无机结合态存在。3.Cd污染土壤工程菌处理小麦籽粒Cd含量比对照处理降低了8.92～26.72%,添加了草木灰的处理能够同时降低小麦籽粒、秸秆及根中Cd的吸收量,其降低率为3.95-67.17%。工程菌与草木灰联合施用小麦籽粒中Cd含量比对照处理降低了14.70～26.70%。4.工程菌处理的污染土壤中,小麦株高增加5.50～11.88 cm,小麦产量增加0.48～1.42 g/盆；小麦粗蛋白含量没有显著差异。施用草木灰处理,小麦株高略有降低,单盆产量增加1.62～2.53 g。5.在本试验中,草木灰通过提高土壤pH值等作用固定污染土壤中的Cd,使其从生物有效态转变为惰性状态,从而减少小麦植株中Cd的吸收量；工程菌的施用也能够降低小麦籽粒对土壤Cd的吸收量,且与草木灰联合施用效果更佳。但无论是草木灰还是工程菌或其联合施用,小麦籽粒中Cd吸收量仍然超过国家食品安全卫生标准GB 2762-2005(Cd<0.1 mg kg-1),在今后的试验中可考虑适当增加草木灰的施用量和构建对重金属具有更强吸附力的工程菌等方式来探寻土壤重金属污染的治理途径。更多还原

【Abstract】 Remediation of heavy metal-contaminated soil received great attention in the recent decades due to the high toxicity and increasing discharge of these pollutants. In contaminated soils, these toxic metals could be absorbed by crops and then enter into the food chains.Brown-red soil collected nearby Shizi mountain, Wuhan, and treated with various levels of Cd (0、1、2、4 mg kg-1 soil) was used in this study, to evaluate the effect of plant ash and genetically engineered bacteria (Pseudomonas putida) on the immobilization and biotoxicity of Cd in wheat(Triticum aestivum L.) potted soils.The main results are outlined as follows:1.No significant changes were observed in soil pH and activity of soil enzymes after application of genetically engineered bacteria. However, soil pH increased by 0.83～1.01 units after application of plant ash with a concentration of 10 g kg-1 soil. Moreover, the activities of sucrose, urease, catalase were promoted with the highest increase by 4.13 times, but that of phosphatase was depressed by 8.18～49.94%.2.In Cd-contaminated soils, the species of Cd were redistributed after application of plant ash and engineered bacteria. The introduction of plant ash caused soluble/exchangeable Cd to convert to inorganic-bound form. In all treated soils, soluble/exchangeable and inorganic-bound Cd accounted for 86.1% of total Cd. Soluble/exchangeable Cd took up 51.6～59.6% of total Cd in contaminated soils without the introduction of plant ash, while 14.68～21.14% of Cd were observed as soluble/exchangeable species and 69.9～82.4% as inorganic-bound species after adding plant ash.3.The content of Cd in the wheat seed was decreased by 8.92～26.72% in engineered bacteria treatment. Cd content in wheat straw, seed and root were reduced by 3.95～67.17% after applying plant ash. The content of Cd in the seed were decreased by 14.70～26.70% due to application of plant ash and engineered bacteria.4.The height of wheat was increased by 5.50～11.88 cm and the dry yield was increased by 0.48～1.42 g per pot with inoculation of engineered bacteria, no effects was observed in the content of crude protein in wheat seeds.The addition of plant ash decreased the height of wheat slightly while increased the dry yield of wheat by 1.62-2.53 g per pot.5.In this experiment, the immobilization of Cd can be strengthened in soil with elevation of soil pH by applying plant ash, which translate bioavailability Cd into inert state, and the accumulation of Cd in wheat seed was reduced; engineered bacteria can also reduce the Cd uptake in wheat seed, a better effect could result from combining with plant ash. However, Cd accumulation of wheat seed in all treatment exceed the national food safety and hygiene standards of GB 2762-2005(Cd<0.1 mg kg-1).Appropriate application of plant ash and construction genetically engineered bacteria of stronger heavy metals adsorption can be considered in future trials to control heavy metal pollution.更多还原