【作者】 史新；

【导师】 谢忠雷；

【作者基本信息】 吉林大学 ， 环境科学， 2013， 硕士

【摘要】 我国农田土壤重金属污染形势日趋严峻，土壤重金属问题已引起人们的广泛关注。Cd是生物毒性较大的重金属元素之一，在土壤中具有化学活性强、迁移性大、毒性持久等特点，且容易通过食物链的富集作用危及人类健康。土壤重金属原位钝化修复技术具有成本低廉、效果快速、操作简单等优点，在土壤污染修复中得到广泛应用，尤其适用于修复大面积中轻度重金属污染农田土壤。本文通过盆栽实验研究了海泡石钝化修复对水稻幼苗生理生化特性的影响，通过盆栽实验和小区试验研究了海泡石钝化修复对水稻体内Cd含量和土壤Cd形态分布以及对土壤环境质量的影响，为土壤Cd污染治理提供理论依据和技术支持。盆栽实验研究结果表明，添加不同量海泡石在不同程度上提高了水稻幼苗叶绿素a、叶绿素b和类胡萝卜素的含量；水稻幼苗叶片和根系超氧化物歧化酶（superoxide dismutase，SOD）与过氧化物酶（peroxidase，POD）活性均在海泡石添加量为50mg·kg^-1时显著升高（P <0.05）；Cd含量为2和5mg·kg^-1时，投加5⁵0mg·kg^-1海泡石，水稻幼苗丙二醛（malondialdehyde，MDA）含量分别降低了28.3%⁷1.0%和69.5%⁸4.4%，显示膜脂过氧化作用减弱。添加海泡石可以缓解土壤Cd污染对植物产生的毒害。添加海泡石后水稻生物量显著增加，Cd含量为5mg·kg^-1时，与对照相比，地上部生物量增加了4.4%⁴1.7%，地下部生物量增加了27.1%⁶7.1%。与之相反，水稻不同部位Cd含量总体上随海泡石添加量的增加而降低，当海泡石添加量达到30g·kg^-1时，稻米中Cd含量达到国家食品卫生标准的要求。小区试验表明，海泡石添加量为10g·kg^-1时水稻产量达到最大值，与对照相比，升高了24.18%。稻米中Cd含量在海泡石添加量为5g·kg^-1时达到国家食品卫生标准的要求。盆栽实验和小区试验中，添加海泡石土壤pH值均升高，可交换态和碳酸盐结合态Cd含量降低，残渣态Cd含量升高，Cd的活性降低。其中盆栽实验条件下，海泡石添加量为10g·kg^-1时残渣态Cd含量最高，而小区试验中，海泡石添加量为15g·kg^-1时交换态和碳酸盐结合态Cd含量最低，残渣态Cd含量最高。盆栽实验和小区试验结果均表明，添加海泡石土壤脲酶活性显著升高。盆栽实验Cd含量为5mg·kg^-1污染水平下，不同海泡石添加量均显著增加了土壤脲酶活性（P <0.05），增加幅度为14.8%³9.0%。小区实验海泡石添加量为10g·kg^-1时土壤脲酶活性最高。盆栽实验土Cd含量为2mg·kg^-1污染水平下，添加海泡石土壤过氧化氢酶活性升高，小区实验过氧化氢酶活性在海泡石添加量为15g·kg^-1时显著升高（P <0.05）。与对照相比，添加海泡石，土壤细菌和真菌数量显著增加，而放线菌数量变化没有明显的规律。更多还原

【Abstract】 Farmland soil polluted by heavy metals in China is increasingly serious, and theproblem has aroused people’s wide concern. Cd is one of heavy metal elements withhigh biological toxicity, which has the characteristics of high chemical activity,mobility, long-time toxicity in soil. And it is easy to endanger human health throughthe food chain. With the advantages of low cost, quick effect, and simple operation,in-situ immobilization remediation technology is widely used in soils contaminated byheavy metals, especially for the light and moderate heavy metal pollution of farmlandsoil in large area. In order to provides theoretical basis and technical support for Cdpollution control in soil, this paper studied the effects of sepiolite on physiologicaland biochemical characteristics of rice seedlings, Cd contents in different parts of riceand Cd form distribution in soil, and its influence to the soil environment quality.The results from the pot experiment revealed that chlorophyll （a）, chlorophyll （b）and carotenoid contents of rice seedlings were all found increased to a different extentwith different treatments of sepiolite. The activities of SOD and POD in the leavesand roots of rice seedlings elevated significantly under50g·kg^-1sepiolite （P <0.05）,as compared with the fact that the MDA contents in rice seedlings with the treatmentsof5⁵0g·kg^-1sepiolite were suffered by28.3%⁷1.0%and69.5%⁸4.4%reductionunder2and5mg·kg^-1Cd stress in contrast with the control group, indicating themembrane lipid peroxidation suffered weakening. It proves that the addition ofsepiolite would alleviate the toxic effect of plants under Cd stress.The dry biomass of rice seedlings shoots and roots tended to increase by20.4%⁷2.7%and27.1%⁶7.1%after the treatments of sepiolite, respectively, underthe Cd concentration of5mg·kg^-1compared to the single Cd contaminated soil.However, the Cd content of different parts of rice decreased with the adding ofsepiolite on the whole, and the Cd content in the editable parts of rice met with thenational standard of hygiene quality for rice （GB2762-2005） when the treatment ofsepiolite was up to30g·kg^-1. In similarly, field experiment showed that the rice production increased by24.18%in contrast with the control, reaching the maximumunder the treatment of10g·kg^-1sepiolite, and the Cd content was below the maximumpermissible concentration when5g·kg^-1sepiolite was added. The pot and fieldexperiment results both showed that the sepiolite treatments increased pH values andthe content of residual Cd, while decreased the content of exchangeable Cd andcarbonate Cd. The residual form of Cd content reach a peak with the treatment of10g·kg^-1sepiolite in pot experiment, while it reached the maximum when15g·kg^-1sepiolite was added in field experiment.The activities of urease, catalase increased after applying sepiolite in ourexperiments have evidently promoted the activity of urease by14.8%³9.0%withdifferent sepiolite added under the Cd concentration of5mg·kg^-1stressed in potexperiments（P <0.05）. The activity of urease was up to the maximum with10g·kg^-1sepiolite treatment in field experiments. In contrast, the activity of catalase showed nosignificant change under5mg·kg^-1Cd, and it increased remarkly under the treatmentof15g·kg^-1sepiolite（P <0.05）. The amount of bacteria and fungi enhancedsignificantly, while the amout of actinomycetes showed disorderly.Therefore, the benefit of sepiolite application to the physiological andbiochemical role of the rice seedlings, to the Cd contents in rice, and to the soilenvironmental quality, proves positive and efficient for the in-situ remediation of Cdcontaminated agricultural sites．更多还原