| 摘要: |
| 近年来，城市工业污染场地严重威胁着人居环境安全，其中土壤铅污染问题比较突出。为加强对铅污染土壤的风险管控，采取磷酸氢二钠（DSP）和植酸（PA）钝化处理铅污染土壤，采用BCR形态分析法和固体废物浸出毒性浸出方法-醋酸缓冲溶液法（HJ/T 300—2007）评价土壤铅赋存化学形态和浸出毒性。结果表明：DSP与PA对污染土壤pH的影响差异比较明显，但均能有效降低污染土壤的铅浸出浓度，并满足生活垃圾填埋场入场标准限值（0.25 mg∙L−1）；随添加比例增加，DSP与PA均能促使土壤中铅元素由活泼态（酸可提取态和可还原态）向稳定态（残渣态）转变，且PA钝化效果优于DSP；两种磷材料处理后的土壤浸出毒性与酸可提取态均表现出显著相关性，同样地，PA优于DSP。可见，PA对铅污染土壤具有良好的固铅作用。 |
| 关键词: 磷酸氢二钠 植酸 铅污染土壤 浸出毒性 化学形态 |
| DOI：10.7515/JEE192003 |
| CSTR： |
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| 基金项目:重庆市科技计划项目（cstc2018jszx-cyzdX0019） |
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| Remediation of lead contaminated soil by organic and inorganic phosphorus materials |
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ZHU Xiaolong, LU Zailiang, QIN Yongjun, PENG Peng
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1. Appraisal Center for Ecology and Environment Engineering of Chongqing, Chongqing 401121, China
2. Chongqing Management and Service Center of Solid Wastes, Chongqing 401121, China
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| Abstract: |
| Background, aim, and scope Recently, the contaminated sites are seriously threatening the safety of urban residential environment, and the problem of lead contamination soil is more prominent. In order to study the stabilizing feasibility and efficiency of phytic acid (PA) for remediation of lead- contaminated soil, the leaching toxicity and corresponding chemical morphological changes of Pb contaminated soils treating separately by PA and disodium hydrogen phosphate (DSP) were studied. Ultimately, it was used to offer a theoretical foundation for further practice of solidification/stabilization remediation of lead-contaminated soil. Materials and methods The lead-contaminated soils, collected from a battery plant in southwest China, were treated by DSP and PA with different proportions (0, 1%, 3%, 5%, 7% and 9%, all of which were mass percentages). The lead chemical forms and its leaching concentration of Pb were analysed by BCR sequential extraction method and Solid waste-Extraction method for leaching toxicity-acetic acid buffer solution method (HJ/T 300—2007). Results The results showed that the tested soil pH were significantly different with DSP and PA, and the leaching concentration of Pb decreased obviously, which met the maximum concentration limits (0.25 mg·L−1) defined by Leachate Treatment Project Technical Specification of Municipal Solid Waste Landfill. The results of BCR speciation analysis showed that both DSP and PA promoted the transformation of Pb from active state to steady state in tested soil, and the effect of PA is better than DSP. Linear regression analysis showed that the positive relationship between the leaching toxicity of the experimental soil and the acid-extractable states, and correlation coefficient in the PA-treated soils were better than DSP. Discussion Although the variations of pH in the tested soil with PA and DSP were obvious different, the leaching concentration of Pb in tested soils decreased significantly, and the maximum drop was up to 98.3% and 98.4% respectively. The main reason was that the chemical forms of Pb in the original soil were reducible fraction (41.0%) ＞ acid-extractable fraction (38.9%) ＞ oxidizable fraction (10.9%) ＞ residual fraction (9.2%). However, due to stabilization by PA and DSP, the chemical forms of lead in tested soil changed significantly. When the ratio of DSP was 7%, the residual state accounted for 52.3% and the acid-extractable state was only 1.4%. When the addition ratio of PA was 9%, the residual state accounted for 67.1%, and the acid-extractable state was only 1.5%. Conclusions Therefore, the leaching toxicity and chemical forms of Pb on contaminated soils stabilizing by DSP and PA showed that the PA was an organic acid, but its unique phosphate group structure made it immobilize effectively Pb, and keep the pH fall between 4 and 6. Recommendations and perspectives This research would have found that PA has good stabilizing efficiency on lead contaminated soils. |
| Key words: disodium hydrogen phosphate phytic acid lead contaminated soil leaching toxicity chemical forms |
