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为探讨促进磷酸盐稳定污染土壤中铅的方法,在全铅含量为517 mg·kg-1的铅冶炼污染土壤中加入5 mmol·kg-1磷酸盐,同时加入10mmol·kg-1硝酸钙或5 mmol·kg-1氯化钾,在15%或30%的含水率下培养40 d,之后种植黑麦草.结果表明,与单独施用磷酸盐相比,采用磷酸盐与钙、氯结合或增加培养期间的土壤含水率后,土壤DTPA-Pb含量下降3.92%~26.1%;对于同一添加剂处理,培养期间土壤含水率从15%增加到30%,土壤有效铅(DTPA-Pb)含量下降8.83%~24.4%.增加土壤含水率后,土壤有效磷(Olsen-P)含量均显著升高(p<0.05).土壤铅的EXAFS分析表明,与未施用磷酸盐的对照相比,土壤中加入磷酸盐后矿物态铅的比例由57%上升至81%,加施钙、氯或增加土壤含水率后,多数处理矿物态铅的比例有所下降,而有机结合态铅比例上升.与对照相比,污染土壤中施用磷酸盐后,植物产量大幅增加,但施用钙、氯或增加培养期间含水率后,部分处理植物产量有所下降.以上结果表明,在铅冶炼污染土壤中加入磷酸盐时,加入钙、氯或者增加土壤含水率均有利于铅的稳定,但以上措施可能对植物生长产生不利影响.
In order to explore the method of promoting the stable pollution of lead in the soil by phosphate, 5 mmol · kg-1 phosphate was added into lead-contaminated soils containing 517 mg · kg-1 lead, and 10 mmol · kg-1 calcium nitrate or 5 mmol · kg-1 KCl, and cultivated for 40 days at 15% or 30% water content before ryegrass planting.The results showed that compared with phosphate alone, the combination of phosphate and calcium, chlorine or increased The soil DTPA-Pb content decreased by 3.92% -26.1% during the incubation period. The soil water content increased from 15% to 30% and the soil available lead (DTPA-Pb) content decreased by 8.83% for the same additive treatment. ~ 24.4%, respectively. The content of soil available phosphorus (Olsen-P) increased significantly (p <0.05) after soil moisture was increased. EXAFS analysis of Pb in soil showed that compared with the control without phosphate, After salt, the proportion of mineral lead increased from 57% to 81%, and after the application of calcium and chlorine or increased soil moisture, the proportion of most lead in mineral processing decreased while the proportion of organic bound lead increased.Compared with the control , The application of phosphates in contaminated soils resulted in a significant increase in plant yield but application of calcium and chloride or increased water cut-off during cultivation , And the yield of some treatments decreased.The above results show that the addition of calcium and chlorine or the increase of soil moisture are beneficial to the stability of lead when phosphate is added into the polluted lead lead smelting soil but the above measures may have an adverse effect on plant growth .