污染控制技术及原理
陈世宝,朱永官,马义兵.磷对降低土壤中铅的生物有效性的X-衍射及电镜分析[J].环境科学学报,2006,26(6):924-929
磷对降低土壤中铅的生物有效性的X-衍射及电镜分析
- Studies on the mechanisms of lead immobilization by phosphorus in soil by XRD, SEM and TEM
- 基金项目：国家杰出青年基金(No.40225002);农业部植物营养与养分循环重点实验室开放基金
- 作者
- 单位
- 陈世宝
- 1. 中国农业科学院农业资源与农业区划研究所, 北京 100081; 2. 中国科学院生态环境研究中心, 北京 100085
- 朱永官
- 中国科学院生态环境研究中心, 北京 100085
- 马义兵
- 中国农业科学院农业资源与农业区划研究所, 北京 100081
- 摘要：通过盆栽实验,对不同磷化合物处理的铅污染土壤和植物分别进行X衍射(XRD)、能谱扫描电镜(SEMEDS)及能谱透射电镜(TEMEDS)分析.结果显示,不同磷化合物处理土样的X衍射图在0.288nm、0.296nm及0.321nm处有明显衍射峰生成,以SSP5、HA5及HASSP2处理土样的X衍射谱图中生成的衍射峰比较明显,而PR5处理的衍射峰相对较弱,其原因可能与磷矿粉的弱溶解特性有关.这显示了土壤经不同磷化合物处理后,土壤中新生成了较多的磷酸铅及CaPb磷酸铅盐的沉淀,不同程度地降低了土壤中铅的迁移和转化特性.对植株根系的SEM分析结果表明,土壤中加入不同的磷化合物处理后,磷酸铅类化合物在植株根表细胞有明显的晶体沉淀物.对植物根细胞的透射电镜分析结果发现,在不同磷处理土壤中,铅以不同的磷酸盐化合物的形式沉淀在植物的细胞壁及细胞间隙,从而有效地阻止了铅离子向原生质细胞及植物中柱内的迁移,不同程度地降低了污染土壤中铅的蓄积毒性.
- Abstract：The mechanisms of immobilization of Pb in contaminated soil by different phosphates amendments were studied by using X-ray diffractometry (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) etc. The X-ray diffraction patterns of the treated soils shown that the formation of the prominent peaks of chloropyromorphite [Pb10(PO4)6Cl2] at 0.296nm, Ca-pyromorphite at 0.288nm and 0.321nm respectively, indicating that less soluble Pb-mineral were formed in situ in the treated soils. However, the peak at 0.296nm was higher in SSP5、HA5 and HA+SSP2 soils than in PR5, suggesting less chloropyromorphite formed in PR5 due to its less solubility. Formation of chloropyromorphite in the treated soils and the plant tissue after P addition were further evidenced by a SEM and TEM microscopy, which showed that Pb was deposited on the cell wall of the plant roots. Combination of SEM, TEM, and XRD results permitted the conclusion that lead ions were immobilized by precipitating Pb(10-x)Cax (PO4)6X2 (X=Cl, OH) compounds in the treated soils and the plant tissues. Based on these results, P- amendments were effective in reducing Pb mobility via in situ formation of insoluble chloropyromorphite etc in the soils.
- Key words：phosphorus lead X-ray diffraction (XRD) scanning electron microscopy (SEM) transmission electron microscopy (TEM)
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