湘中镉污染酸性红壤的钝化修复研究
发布时间：2018-12-28 07:29
【摘要】：化学钝化和植物吸取技术作为土壤重金属污染原位修复的两个重要手段,近年来成为环境领域的研究热点。本研究首先对湖南湘潭土壤重金属修复基地污染状况进行了初步调查,然后以不同污染程度酸性农田土壤为研究对象,通过连续多季盆栽试验,研究了天然海泡石及石灰钝化效果及其持效性,并探讨了钝化修复对后茬吸取修复植物生长和修复效率的影响,在此基础上开展了田间验证试验,以探明Cd污染土壤作物-伴矿景天轮作体系下土壤Cd有效性调控措施。为实现污染土壤耕作季通过钝化修复实现作物安全生产、休耕季利用吸取修复实现污染土壤高效修复的“边生产边修复”技术提供理论依据和技术支持。主要研究结果如下：(1)农田土壤重金属污染状况的调查表明,研究区耕层土壤重金属污染以Cd轻污染为主,平均土壤Cd浓度接近国家土壤环境质量二级标准的2倍。而土壤Pb、Cu和Zn浓度均在二级标准以内；从空间分布看,土壤高浓度Cd和Zn点位主要分布在东部、西北和西南边缘地带；从垂直分布看,剖面表层土壤Cd、Pb、Zn已明显累积,但20 cm以下土层土壤几种重金属浓度均在二级标准以下。(2)海泡石钝化修复盆栽试验结果显示,海泡石及石灰对土壤和作物都产生显著影响。高污染土壤pH值由对照的4.77提高到7.72,土壤Cd有效态浓度最大降低了85.9%。低污染土壤pH值最大提高了3.57个pH单位,土壤Cd有效态浓度最大降低了97.7%;海泡石添加小于2%时,配施石灰效果更明显；且较长时间内,海泡石促进小青菜生长和降低其对Cd的吸收。其中低污染土壤,海泡石添加2%及以上,小青菜Cd浓度连续四季均符合国家食品卫生标准。土壤和作物相关指标连续多季结果相似,说明钝化效果能持续一年或更久。(3)田间条件下钝化修复结果发现,海泡石及石灰对土壤pH值及Cd有效性均有显著影响。与对照相比,土壤pH提高了0.41-0.86个pH单位,Cd有效态浓度降低了37.5%-85.7%,而水稻各时期根、秸秆、谷壳及糙米Cd浓度有所降低,但无显著差异。(4)钝化修复对后茬吸取修复植物生长和修复效率影响结果表明,适量海泡石对伴矿景天的生长及Cd吸收影响不大,较高剂量添加不利于伴矿景天的吸取修复。
[Abstract]:Chemical passivation and phytoremediation are two important methods for in situ remediation of heavy metal pollution in soil. In recent years, chemical passivation and phytoremediation have become the research focus in the field of environment. In this study, the pollution status of heavy metal remediation base in Xiangtan soil in Hunan Province was investigated, and then the acid farmland soil with different levels of pollution was used as the research object, and the pot experiment was carried out in succession of seasons. The passivation effect of natural sepiolite and lime and its persistence were studied. The effects of passivation and restoration on the growth and restoration efficiency of subsequent stubble remediation plants were discussed. Based on this, field validation experiments were carried out. The effective control measures of soil Cd under the rotation system of Cd contaminated soil crop and Jinjingtian were investigated. In order to realize the safe production of crops by passivation remediation in tillage season of contaminated soil, and to provide theoretical basis and technical support for the technology of "remediation while production while repairing" in fallow season, which can be used to achieve efficient remediation of contaminated soil by absorption remediation in fallow season. The main results are as follows: (1) the investigation of heavy metal pollution in farmland soil showed that the heavy metal pollution in the cultivated layer was mainly caused by Cd light pollution, and the average Cd concentration was close to 2 times of the national second grade standard for soil environmental quality. The concentration of Pb,Cu and Zn in soil was within the second grade standard, and the spatial distribution of high concentration Cd and Zn in soil was mainly in the eastern, northwest and southwest marginal areas. From the vertical distribution, Cd,Pb,Zn accumulated obviously in the surface soil of the profile, but the concentrations of several heavy metals in the soil layer below 20 cm were below the second grade standard. (2) the results of pot experiment of sepiolite passivation restoration showed that Sepiolite and lime have significant effects on soil and crops. The pH value of highly polluted soil increased from 4.77 to 7.72, and the available concentration of Cd decreased by 85.9%. The maximum pH value of low-polluted soil increased 3.57 pH units, and the maximum effective concentration of Cd decreased 97.70.When sepiolite was added less than 2, the effect of lime application was more obvious. For a long time, sepiolite promoted the growth and decreased the absorption of Cd. The low pollution soil, sepiolite added 2% and above, the Cd concentration of small green vegetables all accord with the national food hygiene standard for four consecutive seasons. Soil and crop related indexes were similar in successive seasons, indicating that the passivation effect could last for one year or longer. (3) the results of passivation and remediation under field conditions showed that sepiolite and lime had significant effects on soil pH value and Cd availability. Compared with the control, soil pH increased 0.41-0.86 pH units, Cd effective state concentration decreased 37.5% and 85.75.75%, while the Cd concentration of rice root, straw, husk and brown rice decreased. But there was no significant difference. (4) the effects of passivation and restoration on the growth and restoration efficiency of the plant showed that the proper amount of sepiolite had little effect on the growth and Cd absorption of Sedum. Higher dose addition is unfavorable to the drainage and restoration of Sedum.
【学位授予单位】：湖南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53
本文编号：2393678
[Abstract]:Chemical passivation and phytoremediation are two important methods for in situ remediation of heavy metal pollution in soil. In recent years, chemical passivation and phytoremediation have become the research focus in the field of environment. In this study, the pollution status of heavy metal remediation base in Xiangtan soil in Hunan Province was investigated, and then the acid farmland soil with different levels of pollution was used as the research object, and the pot experiment was carried out in succession of seasons. The passivation effect of natural sepiolite and lime and its persistence were studied. The effects of passivation and restoration on the growth and restoration efficiency of subsequent stubble remediation plants were discussed. Based on this, field validation experiments were carried out. The effective control measures of soil Cd under the rotation system of Cd contaminated soil crop and Jinjingtian were investigated. In order to realize the safe production of crops by passivation remediation in tillage season of contaminated soil, and to provide theoretical basis and technical support for the technology of "remediation while production while repairing" in fallow season, which can be used to achieve efficient remediation of contaminated soil by absorption remediation in fallow season. The main results are as follows: (1) the investigation of heavy metal pollution in farmland soil showed that the heavy metal pollution in the cultivated layer was mainly caused by Cd light pollution, and the average Cd concentration was close to 2 times of the national second grade standard for soil environmental quality. The concentration of Pb,Cu and Zn in soil was within the second grade standard, and the spatial distribution of high concentration Cd and Zn in soil was mainly in the eastern, northwest and southwest marginal areas. From the vertical distribution, Cd,Pb,Zn accumulated obviously in the surface soil of the profile, but the concentrations of several heavy metals in the soil layer below 20 cm were below the second grade standard. (2) the results of pot experiment of sepiolite passivation restoration showed that Sepiolite and lime have significant effects on soil and crops. The pH value of highly polluted soil increased from 4.77 to 7.72, and the available concentration of Cd decreased by 85.9%. The maximum pH value of low-polluted soil increased 3.57 pH units, and the maximum effective concentration of Cd decreased 97.70.When sepiolite was added less than 2, the effect of lime application was more obvious. For a long time, sepiolite promoted the growth and decreased the absorption of Cd. The low pollution soil, sepiolite added 2% and above, the Cd concentration of small green vegetables all accord with the national food hygiene standard for four consecutive seasons. Soil and crop related indexes were similar in successive seasons, indicating that the passivation effect could last for one year or longer. (3) the results of passivation and remediation under field conditions showed that sepiolite and lime had significant effects on soil pH value and Cd availability. Compared with the control, soil pH increased 0.41-0.86 pH units, Cd effective state concentration decreased 37.5% and 85.75.75%, while the Cd concentration of rice root, straw, husk and brown rice decreased. But there was no significant difference. (4) the effects of passivation and restoration on the growth and restoration efficiency of the plant showed that the proper amount of sepiolite had little effect on the growth and Cd absorption of Sedum. Higher dose addition is unfavorable to the drainage and restoration of Sedum.
【学位授予单位】：湖南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53
【参考文献】
相关期刊论文 前2条
1 孙约兵;徐应明;史新;王林;梁学峰;;海泡石对镉污染红壤的钝化修复效应研究[J];环境科学学报;2012年06期
2 王林;徐应明;梁学峰;孙国红;孙约兵;林大松;;广西刁江流域Cd和Pb复合污染稻田土壤的钝化修复[J];生态与农村环境学报;2012年05期
，本文编号：2393678
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