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摘要：近年来，我国土壤的重金属污染问题日益严重，重金属Pb、Hg、Cr、Cu等及其复合物通过食物链在生物体内进行富集，已经对土壤质量、农产品品质、人类健康等构成了严重的威胁。目前土壤重金属污染的修复方法有物理、化学、生物及其联合修复法。本文主要选取栖霞、韶关、常安三地的土样，研究其淋洗前后土壤团聚体中养分和重金属含量变化规律；采用BCR三级提取法对淋洗前后的三种土样团聚体中重金属的不同形态（酸溶态、可还原态、可氧化态和残渣态）进行提取；对淋洗后土样中常量元素的溶出进行分析；以Fe、Al元素为例探究淋洗前后游离态、非晶态、络合态三种形态的变化。通过这四个方面简单探究化学淋洗修复重金属土壤的机理。结果表明，随着土样粒径的减小，土样团聚体中的重金属和养分含量向粘粒级富集增大；100 mmol•L-1柠檬酸+20 mmol•L-1 FeCl3复合淋洗土样，对Pb、Cd、Zn和Cu四种重金属的去除率最高，比单独使用柠檬酸淋洗率平均提高了31.83%,比单独使用FeCl3淋洗率平均提高了24.07%；重金属Pb、Cd、Zn和Cu的淋洗率为粗粉砂级>粉砂级>砂粒级>粘粒级。25919
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毕业论文关键词：土壤团聚体；重金属；化学淋洗
Study on the Effect of the Reduction of Heavy Metal in Contaminated Soils by Chemical Washing
Abstract：In recent years, the problem of heavy metal pollution of soil in China is becoming increasingly serious, heavy metals Pb, Hg, Cr, Cu and the compound through the food chain in vivo enrichment, has posed a serious threat to soil quality, the quality of agricultural products and human health. At present, the methods for remediation of soil heavy metals pollution are physical, chemical, biological and combined remediation methods.This paper selected Qixia, Shaoguan, soil samples from Chang An three, to study the leaching before and after soil nutrients and heavy metal content changes; different forms of the three BCR extraction method for leaching and three soil samples in aggregates of heavy metals (acid soluble and reducible, oxidizable and residual) the major elements were extracted; leaching in the soil samples dissolution were analyzed with Fe and Al elements; an inquiry after washing free, non crystalline, complex state of three kinds of changes. Through these four aspects, we simply explore the mechanism of chemical leaching remediation of heavy metal soil. The results show that with the decrease of the size of soil particles, heavy metals and nutrient content of soil aggregates to clay enrichment increased; 100 mmol•L-1 +20 mmol•L-1 FeCl3 citric acid leaching of composite soil samples, Pb, Cd, Zn and Cu four kinds of heavy metals in the highest removal rate than the single use of citric acid the leaching rate increased by 31.83%, than the single FeCl3 leaching rate increased by 24.07%;The leaching rates of heavy metals Pb, Cd, Zn and Cu are coarse silty sand grade > silty sand grade > sand particle grade > clay grade.
Key words: soil aggregate;heavy metal;chemical washing
目 录
摘要1
关键词1
Abstract1
Key words1
引言 1
1材料与方法 2
1.1实验土样 2
1.2所用试剂及仪器 3
1.3重金属分级形态的测定 3
1.4淋洗液中的金属离子的测定3
1.5土壤团聚体的淋洗4
1.6数据处理 4
2 实验结果分析4
2.1土样团聚体的组成4
2.2淋洗效果与淋洗率 6
2.3土样团聚体中重金属的形态变化及形态分分析 7
3 总结 11
致谢11
参考文献12
重金属污染土壤化学淋洗修复机理的研究
引言
近年来，随着工农业的迅速发展,环境污染和生态破坏日益严峻，严重影响到了人类的健康和生存，其中重金属元素对环境的污染和破坏作用尤为严重，特别是Pb、Hg、Cr、Cu及其复合污染最为突出。污水的农田灌溉、污泥的农业利用、畜禽废弃物和无机肥料的施用皆会导致了部分土壤被重金属污染，同时土壤肥力退化，作物产量和品质降低[1]。且土壤中的重金属可以通过食物链在生物体内进行富集[2]，土壤中重金属元素的化学形态及其与土壤物质的结合形式是影响其迁移活动性和生物可利用性的主要原因。重金属在土壤中可被土壤组分如：土壤黏粒、土壤中的有机质等吸附在表面；也可与土壤矿物质如：与土壤矿物如碳酸盐、铁氧化合物、硫化物等结合形式存在[3]。重金属的生物毒性不仅与环境中所含重金属含量的多少有关，还与其形态分布有很大关系。不同的形态会产生不同的环境效应，可以直接影响到重金属的毒性、在环境中的迁移与与其在自然界的循环[4]。