| 磷对铅、锌和镉在土壤固相-液相-植物系统中迁移转化的影响 |
| 摘要点击 2518 全文点击 1279 投稿时间：2007-11-27 修订日期：2008-02-25 |
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| 中文关键词 重金属 磷 修复 土壤-植物系统 界面迁移 |
| 英文关键词 heavy metal phosphorus remediation soil-plant system translocation |
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| 中文摘要 |
| 在盆栽条件下，以磷酸二氢钾作为磷（P）添加剂，以空心菜为指示植物，借助模型Visual MINTEQ 研究了P对污染土壤中铅（Pb）、锌（Zn）和镉（Cd）在土壤固相-液相之间以及土壤-根系-地上部的迁移累积的影响.实验设了6个P剂量水平：0（CK）、 0.18（P0.18）、 0.36 （P0.36）、 0.72（P0.72）、 1.08（P1.08）、 1.44（P1.44），P剂量水平是按照P/Pb物质量的比例（mol/mol）为基础而设计的.结果表明，与对照相比，添加P处理污染土壤后，显著（p<0.05）降低了空心菜地上部吸收的重金属Pb、Zn和Cd的含量，降低幅度分别为53％～92％、 35％～71％和59％～86％，降低了根系吸收累积重金属Pb的含量，增加了根系吸收的Zn的含量，但对Cd吸收量无显著影响.增加P的剂量水平，根系向地上部转运的Pb、Zn和Cd的量的呈指数级下降趋势.地上部吸收的各元素的相关分析结果表明，元素Pb 与元素Zn、Cd是显著正相关关系，其中相关系数最高的是Pb 与Zn（R＝0.993，p<0.01），其次是Pb与Cd（R＝0.986，p<0.01）.说明Pb 与Zn、Cd在空心菜从根系到地上部分转运的过程中是协作关系.添加P后，提高了土壤pH，从而降低了土壤水溶性Cd的含量，Zn变化不显著，增加了土壤水溶性总Pb含量.平衡液中Pb的主要存在形态是PbHPO4、PbOH+、PbH2PO+4等3种络合形态.结果还表明，根系吸收Pb的量与土壤水溶性Pb含量具有显著的负相关关系，相关系数-0.872（p<0.05）.P处理降低了土壤水溶性Zn、Cd的含量，却促进了根系吸收，这是Zn、Cd与Pb的不同之处.P具有显著降低复合污染土壤中Pb、Zn和Cd植物毒性的作用. |
| 英文摘要 |
| A pot experiment was conducted to determine the influence of phosphorus (P) application on the translocation and accumulation of lead (Pb)，zinc (Zn)，and cadmium (Cd) in a soil solid-liquid-plant system using a plant Swamp Morningglory (Ipomoea aquatica Forsk) as an indicator and Visual MINTEQ model.A contaminated soil containing 22 830 mg·kg-1 Pb，746 mg·kg-1 Zn，and 10 mg·kg-1 Cd was amended with P as KH2PO4 at 0∶1，0.18∶1，0.36∶1，0.72∶1，1.08∶1，and 1.44∶1 P∶Pb mole ratios.The results showed that Pb concentration in the root was significantly decreased after P application，while the Zn concentration were increased，but no impact on Cd concentration after P application，compared to the control.Further more，concentrations of Pb，Zn，and Cd in plant tissue were sharply reduced after P application by 53％-92％， 35％-71％，and 59％-86％，respectively; Concentrations decreased exponentially with increasing amount of P; Relationship between Pb and Zn (R=0.993，p<0.01)，between Pb and Cd (R＝0.986，p<0.01) suggested that there was a positive relationship between the mechanisms controlling the phytoavailability of Pb，Zn，and Cd.It was suggested that Cd concentrations in the soil solution were reduced generally by P application as a result of the increased soil pH，and Zn concentrations were no changed，but Pb concentrations were increased.Species distribution showed that PbHPO4，PbOH+ and PbH2PO+4 were the main complexation species of Pb in the soil equilibrium solution after P application.It was also suggested that Pb accumulation by root were negatively correlated to Pb in soil solution with coefficient of -0.872(p<0.05)，and that water soluble Zn and Cd concentrations were reduced while the concentrations in root tissues were increased after P addition.These results indicate the difference between Zn，Cd and Pb and suggest that P as KH2PO4 successfully decreased the phytotoxicity of Pb，Zn，and Cd in the contaminated soil. |
