潼关某重金属污染农田的化学—植物联合修复研究

发布时间：2018-03-29 18:09

本文选题：土壤　切入点：重金属　出处：《西北农林科技大学》2015年硕士论文

【摘要】：土壤是人类赖以生存和发展的物质基础,也是生态环境的重要组成部分。2014年4月17日,中国环境保护部、国土资源部联合发布全国土壤污染状况调查公报显示,中国土壤污染物点位超标率为16.1%,重金属污染占82.8%,土壤重金属污染治理迫在眉睫。本试验以潼关县某重金属污染农田为研究对象,在对试验区污染状况进行调查的基础上,施用粉煤灰(2.5t/亩)对污染土壤进行了原位修复,用TCLP法进行评估,并通过种植串叶松香草、向日葵、三叶鬼针草、繁穗苋、黑麦草、曼陀罗6种草本植物和木本植物德国杨树、柳树研究木本植物和草本植物间作条件下对Cd的提取能力和修复年限。结果表明:(1)试验区农田土壤中重金属Cd污染最为严重,其次为Hg和Pb。Cd和Hg的平均含量分别为3.70mg/kg、1.64mg/kg,是《土壤环境质量标准》(GB15618-1995)二级标准值的6.17、1.64倍。(2)Cd、Pb和Hg的TCLP提取态平均含量分别为1.74mg/kg、9.45mg/kg和0.69×10-3 mg/kg,Cd和Pb平均含量分别是国际标准值的3.5倍和1.9倍,Hg的有效态含量较低。三种重金属元素有效态含量占全量的比例差异较大,并以Cd所占比例最高,平均达47.10%,Pb为8.07%,Hg的有效态含量占全量比例最低,为0.42%。(3)经粉煤灰钝化后,Hg、Cd和Pb的有效态含量平均值分别降低28.57%、24.36%和31.83%。Pb和Hg经粉煤灰钝化后有效态含量基本降低到国际标准值以内。钝化后Cd有效态含量最高达到1.8mg/kg,仍具有较高的环境危害性,需要进一步采用植物修复技术强化修复效果。(4)繁穗苋和三叶鬼针草分别与德国杨树间作对Cd的修复效果较好,若按每年刈割3茬计算,修复所需时间分别为6a和7.8a。在粉煤灰钝化基础上进行植物修复,繁穗苋和三叶鬼针草分别与德国杨树间作需要4a和5.1a。
[Abstract]:Soil is not only the material basis for human survival and development, but also an important part of the ecological environment. On April 17, 2014, China's Ministry of Environmental Protection and the Ministry of Land and Resources jointly issued a national soil pollution survey bulletin, The excess rate of soil pollutants in China is 16.1%, heavy metal pollution accounts for 82.8%, and the treatment of soil heavy metal pollution is urgent. This experiment took a heavy metal contaminated farmland in Tongguan County as the research object, based on the investigation of the pollution situation in the experimental area. In situ remediation of contaminated soil was carried out by using fly ash 2.5 t / mu, and evaluated by TCLP method. Six kinds of herbaceous plants, six woody plants, six herbs and six woody plants, German poplar, were cultivated by planting rosin, sunflower, trefoil, purslane, ryegrass, mandola and German poplar. The CD extraction ability and remediation years of willow trees under the condition of intercropping between woody plants and herbaceous plants were studied. The results showed that CD pollution in farmland soil was the most serious in the experiment area. The average content of Hg, Pb.Cd and Hg was 3.70 mg / kg 1.64 mg / kg, respectively, which was 6.17 ~ 1.64 times of the second class standard value (GB 15618-1995). The average contents of TCLP extracted CD and Hg were 1.74 mg / kg 路kg 9.45 mg / kg and 0.69 脳 10 ~ (-3) mg 路kg ~ (-1) 路kg ~ (-1) CD and Pb, respectively. The available state contents of 3.5 times and 1.9 times Hg were lower, and the ratio of available state contents of the three heavy metal elements to the total amount was quite different. The percentage of CD was the highest, and the effective state content of Hg was the lowest with the average value of 47.10% and 8.07%, respectively. After passivation by fly ash, the available state contents of CD and Pb decreased by 28.57% and 24.36%, respectively, and the effective state contents of 31.83%.Pb and Hg by fly ash passivation were basically reduced to the international standard value. The highest effective state content of CD after passivation was 1.8 mg / kg / kg. With high environmental hazards, It is necessary to further use phytoremediation technique to strengthen the effect of remediation. 4) the effect of intercropping of purslane and Herba trilobifolia with German poplar is better than that of German poplar, if the effect is calculated by cutting 3 stubble per year. The restoration time was 6 years and 7.8 years, respectively. Phytoremediation was carried out on the basis of the passivation of fly ash, and the intercropping of purslane and Herba trilobifolia with German poplar needed 4 years and 5.1 years, respectively.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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