低分子有机酸、腐殖酸对土壤镉污染淋洗修复研究

发布时间：2018-01-26 09:11

本文关键词： 柠檬酸草酸酒石酸腐殖酸镉化学淋洗修复　出处：《四川农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：利用化学淋洗剂可以活化和络合土壤中的重金属,达到减轻土壤重金属污染的目的。本文选取不同淋洗剂通过室内模拟试验和实际矿山土壤修复试验讨论了对土壤镉污染的淋洗效果以及淋洗后对土壤中镉形态和土壤基本性质的影响,探讨不同淋洗剂的修复效果。主要研究结果分述如下。三种低分子量有机酸对镉的淋洗率均随着淋洗剂浓度的升高而升高,同一浓度下,柠檬酸对镉淋洗率显著高于草酸与酒石酸(P0.05)。淋洗液不同pH条件下三种低分子有机酸淋洗液对镉的淋洗特征表现为,柠檬酸的镉淋洗率随pH的升高先升高后降低；草酸和酒石酸的镉淋洗率随pH的升高而降低。当pH为7.0时柠檬酸对镉淋洗率分别是草酸和酒石酸的8倍和9倍；与淋洗前相比,淋洗后土壤残渣态的镉所占的比重增加了30%-40%(P0.05)。其中,当pH大于7时经草酸和酒石酸淋洗后的土壤残渣态镉所占比重均超过50%。不同浓度低分子有机酸淋洗后对土壤有机质含量影响不明显,但随着淋洗液pH的升高,土壤有机质含量总体呈减少趋势；与淋洗前相比,不同浓度低分子有机酸淋洗后土壤全氮和全磷含量显著降低。其中,当酒石酸浓度为1%时淋洗后土壤全氮、全磷和全钾含量与淋洗前相比分别降低了42%,75%和20%。不同pH低分子有机酸淋洗液淋洗后对土壤全氮含量与淋洗前相比显著降低,但随着淋洗液pH的升高,土壤全氮含量显著升高。不同pH柠檬酸淋洗液淋洗后土壤全磷含量变化与淋洗前相比没有显著变化(P0.05)。低浓度腐殖酸对土壤镉污染具有较突出的清除效果。当腐殖酸pH为5.0时镉的淋洗率最高。另外,富里酸与氯化钾组合淋洗剂对土壤镉的淋洗效果随着淋洗时间的增加表现出现先增加后降低的趋势。当富里酸浓度为0.05%,淋洗时间为2小时时,淋洗率达到了98.2%。各浓度腐殖酸淋洗后土壤残渣态均超过50%酸性条件下淋洗后土壤镉主要以可交换态为主。当淋洗时间为4小时时,各浓度富里酸与氯化钾组合淋洗后土壤残渣态镉占总镉的比重是淋洗前的1.07-1.43倍。不同浓度腐殖淋洗后土壤有机质含量随着腐殖酸浓度的增加而增加。另外,随着腐殖酸淋洗液pH的升高,淋洗后土壤有机质含量先升高后降低。与淋洗前相比,不同浓度腐殖酸淋洗后土壤全氮和全磷含量显著降低；不同浓度腐殖酸淋洗前后土壤全钾与淋洗前相比无显著变化。不同pH腐殖酸淋洗后土壤全氮和全磷与淋洗前相比显著降低(P0.05),但土壤全钾含量与淋洗前相比没有显著变化(P0.05)。富里酸和氯化钾组合淋洗剂淋洗后土壤全氮和全磷随着淋洗时间的增加而显著降低。然而,组合淋洗剂淋洗后对土壤全钾无明显影响矿山土壤淋洗修复试表明,与有机酸相比,腐殖酸、富里酸与氯化钾组合淋洗剂的镉淋洗较高；各淋洗剂淋洗后土壤残渣态镉所占比重占总镉比重均超过50%。综上所述,腐殖酸、富里酸与氯化钾组合淋洗剂对矿山土壤镉污染有较好的淋洗修复能力。
[Abstract]:The use of chemical leaching heavy metals can be activated and complex in the soil, reduce soil heavy metal pollution. Effects of cadmium in soil morphology and soil basic properties this paper selects different eluent through laboratory simulation test and practical test of mine soil remediation is discussed. The results of leaching of cadmium polluted soil and leaching, to investigate the effect of different repair eluant. The main results are as follows. Three kinds of low molecular weight organic acids on cadmium leaching rate were increased with the eluent concentration, at the same concentration of citric acid on cadmium leaching rate significantly higher than that of oxalic acid and tartaric acid (P0.05). The eluent under different pH conditions of three kinds of low organic acid eluent leaching characteristics of cadmium, cadmium leaching rate of citric acid with the increase of pH first increased and then decreased; oxalic acid and tartaric acid leaching rate of cadmium decreased with rising pH when pH is 7. .0 of citric acid on cadmium leaching rate of oxalic acid and tartaric acid is 8 times and 9 times; compared with before leaching, leaching of soil residual cadmium increased the proportion of 30%-40% (P0.05). Among them, no significant effect on soil organic matter content when pH is larger than 7 by soil cadmium residue oxalic acid and tartaric acid leaching after the proportion of more than 50%. of different concentrations of low molecular organic acid leaching, but with the increase of eluent pH, soil organic matter content decreased; compared with before leaching, different concentrations of low molecular organic acid leaching of soil total nitrogen and total phosphorus content decreased significantly. Among them, when the tartaric acid concentration is 1% after leaching of soil total nitrogen, total phosphorus and total potassium content and compared before leaching were reduced by 42%, 75% and 20%. different pH low molecular organic acid as eluent after leaching of soil total nitrogen content decreased significantly compared with before leaching, but with the eluent p The increase of H, soil total nitrogen content increased significantly. Different soil pH citric acid as eluent after leaching and leaching of total phosphorus content changes than before did not change significantly (P0.05). Low concentration of humic acid has prominent scavenging effect on cadmium contaminated soil. When humic acid pH 5 CD leaching rate was the highest. In addition, the combination of fulvic acid and potassium chloride leaching agent to soil cadmium leaching effect with leaching time increase showed increased first and then decreased. When the concentration of fulvic acid was 0.05%, leaching time is 2 hours, the leaching rate of 98.2%. in different concentration of humic acid in soil after leaching residue was more than 50% under acidic conditions after leaching of cadmium in soil mainly in the exchangeable form. When the leaching time is 4 hours, the concentration of fulvic acid and potassium chloride combined soil treated with cadmium residue in proportion to the total cadmium is 1.07-1.43 times before leaching. Different concentrations of humic leaching After the content of soil organic matter increased with the increase of humic acid concentration increased. In addition, with the increase of humic acid as eluent pH, soil organic matter content increased first and then decreased. After leaching compared with before leaching, different concentrations of humic acid leaching of soil total nitrogen and total phosphorus content decreased significantly; different concentrations of humic acid leaching and soil with potassium before leaching showed no significant change. Different pH humic acid leaching and leaching of soil total nitrogen and total phosphorus was significantly lower than before (P0.05), but the content of total potassium in soil and leaching than before (P0.05). There was no significant change in fulvic acid and potassium chloride combined with the eluent after soil total nitrogen and total phosphorus with the increase of leaching time and significantly decreased. However, combined with the eluent of soil total potassium had no obvious effect on mine soil leaching remediation test showed that, compared with the organic acid, humic acid, fulvic acid and potassium chloride leaching agent combination Cadmium leaching is relatively high. After leaching, the proportion of total cadmium in soil residue is more than 50%.. In conclusion, humic acid, fulvic acid and potassium chloride combined leaching agent have good leaching and remediation ability for cadmium pollution in mining soil.

【学位授予单位】：四川农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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