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本文通过试验方法分析磷酸氢二铵(DAP)、磷酸二氢钾(MPP)、过磷酸钙(SSP)和磷酸钙(TCP)四种磷肥对污染土壤中镉的毒性和生物有效性的影响.同时,从两方面评价土壤重金属镉的迁移能力,一方面分析 TCLP 法提取态镉浓度减少量,另一方面分析与土壤不同结合态的镉组分含量变化.结果表明：试验50天时,四种磷肥处理的土壤中重金属镉提取态浓度从42．64 mg/kg 分别下降至23．86,21．86,33．89,and 35．59 mg/kg,迁移能力强弱为 MPP ＞ DAP ＞ SSP ＞ TCP.对重金属镉形态评价表明,磷肥处理后的污染土壤中,交换态镉浓度显著降低.此外,稳定态镉(铁锰氧化物结合态镉)含量相对升高.处理的有效性随着、磷镉比(PO4/Cd)的升高而升高,最佳磷镉比为4：1.“,”A laboratory investigation was conducted to evaluate the efficiency of four phosphate fertilizers,including diammonium phosphate (DAP),potassium phosphate monobasic (MPP),calcium superphosphateon (SSP),and calcium phosphate tribasic (TCP),in terms of the toxicity and bioavailability of Cd in contaminated soils.The efficiency of immobilization was evaluated on the basis of two crite-ria:(a)the reduction of extractable Cd concentration below the TCLP regulatory level and (b)the Cd changes associated with specific op-erational soil fractions on the basis of sequential extraction data.Results:showed that after 50 d immobilization,the extractable concentra-tions of Cd in DAP,MPP,SSP,and TCP treated soils decreased from 42.64 mg/kg (in the control)to 23.86,21 .86,33.89,and 35.5 9 mg/kg,respectively,with immobilization efficiency in the order of MPP > DAP > SSP > TCP.Results:from the assessment of Cd spe-ciation via the sequential extraction procedure revealed that the soluble exchangeable fraction of Cd in soils treated with phosphate fertiliz-ers,especially TCP,was considerably reduced.In addition,the reduction was correspondingly related to the increase in the more stable forms of Cd,that is,the metal bound to manganese oxides and the metal bound to crystalline iron oxides.Treatment efficiency increased as the phosphate dose (according to the molar ratio of PO4/Cd)increased.Immobilization was the most effective under the molar ratio of PO4/Cd at 4:1 .