铅锌复合污染土壤的钝化修复与土壤酶活性研究

发布时间：2018-11-19 18:06

【摘要】：近年来土壤重金属污染带来的环境问题日益突出,我国总膳食研究表明重金属污染对人类健康有巨大的潜在危害。“十二五”规划提出了重金属污染的治理,对土壤重金属污染的治理势在必行。本研究以广西河池市大环江流域铅锌矿尾砂污染农田土壤为研究对象,选用海泡石与具广西特色的蚕沙、椰糠和赤泥进行化学钝化修复实验,通过土壤培养试验,研究不同钝化剂对土壤理化性质,土壤酶活性和植物有效性的影响。取得如下主要结果：(1)赤泥和蚕沙属于碱性物质,添加后均对土壤pH值有显著提高,赤泥+蚕沙效果更为明显；椰糠略微降低了土壤的pH值,海泡石对pH值影响不显著。蚕沙和椰糠均富含有机质,添加后均大大提高土壤有机质含量,改善了土壤环境。复合钝化处理使铅锌的TCLP提取态降低的效果优于单施钝化处理,有机物料的钝化效果优于无机钝化剂处理；降低土壤Pb、Zn弱酸提取态效果最好的分别是蚕沙、赤泥+蚕沙,能明显提高其残渣态含量的均是赤泥+蚕沙。(2)蚕沙及其复合材料钝化处理对土壤脲酶活性起到显著激活作用；单施椰糠钝化剂使得土壤蔗糖酶活性恢复得最好；土壤过氧化氢酶活性在钝化剂的钝化修复下均有了明显的提高。在治理酸性重金属污染土壤时,在一定范围内提高土壤pH值、有机质含量和以及降低重金属有效态含量能有效恢复土壤酶活性。(3)小白菜盆栽实验结果显示,复合钝化剂的钝化效果比单施钝化剂要好,单施材料中高pH材料的钝化效果又比低pH材料好。蚕沙及其复合钝化剂对土壤Pb、Zn的钝化效果最好,使小白菜体内Pb、Zn含量最低,对小白菜产量提高作用最明显。但钝化处理后小白菜依然存在很大的食用安全隐患,建议在污染程度严重的土壤种植非食用或高抗性的经济作物。(4)分析土壤pH值和有机质含量与重金属铅锌的相关性,发现土壤pH值与有机质含量能在一定程度上降低弱酸提取态铅锌含量和提高残渣态铅锌含量,在一定程度上降低铅锌的迁移性和生物有效性。综合效果看,蚕沙的钝化效果最好。将蚕沙、椰糠、赤泥用于修复大面积中低度重金属污染土壤具有经济高效的优越性。
[Abstract]:In recent years, the environmental problems caused by soil heavy metal pollution have become increasingly prominent. The total dietary research in China shows that heavy metal pollution has great potential harm to human health. The "12th Five-Year Plan" proposed the treatment of heavy metal pollution, and the treatment of soil heavy metal pollution is imperative. In this study, the Pb-Zn mine tailings polluted farmland soil in Dahuanjiang Valley, Hechi City, Guangxi Province as the research object, sepiolite and silkworm sand, coconut chaff and red mud with Guangxi characteristics were selected for chemical passivation and restoration experiments, and soil culture experiments were carried out. The effects of different passivating agents on soil physical and chemical properties, soil enzyme activity and plant availability were studied. The main results were as follows: (1) Red mud and silkworm sand were alkaline substances, and the pH value of soil was significantly increased after addition, and the effect of silkworm sand in red mud was more obvious, and coconut chaff slightly decreased the pH value of soil, but sepiolite had no significant effect on pH value. Silkworm sand and coconut bran are rich in organic matter. The compound passivation treatment can reduce the TCLP extraction state of lead and zinc better than that of single passivation treatment, and the passivation effect of organic material is better than that of inorganic passivator treatment. Silkworm sand, red mud silkworm sand and red mud silkworm sand were the best ones to reduce the weak acid extraction of soil Pb,Zn. It was red mud silkworm sand that could significantly increase the residual state content. (2) the silkworm sand and its composite material passivation could activate soil urease activity significantly; Application of coconut bran passivating agent alone could make soil sucrase activity recover best, and soil catalase activity increased obviously under passivation and repair of passivating agent. In the treatment of acidic heavy metal contaminated soil, increasing soil pH value, content of organic matter and reducing the content of available heavy metals can effectively restore soil enzyme activity. (3) the pot experiment of pakchoi showed that the soil enzyme activity could be effectively restored by increasing the content of soil organic matter and reducing the content of available heavy metals. The passivation effect of the compound passivator is better than that of the single application of passivating agent, and the passivation effect of the high pH material in the single application material is better than that of the low pH material. Silkworm sand and its compound passivating agent had the best passivation effect on soil Pb,Zn. The content of Pb,Zn in pakchoi was the lowest and the effect on the yield of pakchoi was the most obvious. However, after passivation treatment, pakchoi still has great potential food safety problems. It is suggested that non-edible or high-resistant cash crops should be planted in heavily polluted soil. (4) the correlation between soil pH value and organic matter content and heavy metal, lead and zinc is analyzed. It was found that pH value and organic matter content of soil could reduce the content of lead and zinc in weak acid extract and increase the content of residual lead and zinc to some extent, and reduce the migration and bioavailability of lead and zinc to a certain extent. Comprehensive effect, silkworm sand passivation effect is the best. The application of silkworm sand, coconut bran and red mud to remediation of heavy metal contaminated soil in large area has economic and efficient advantages.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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