利用低能量超声波分散、虹吸法沉降分离的方法分离不同粒径的水稻土团聚体颗粒，采用恒温振荡法研究不同浓度磷酸盐预处理的团聚体对Cd2+、Cr(Ⅵ)平衡吸附以及吸附动力学的影响。结果表明，砂粒级、粗粉砂级、粉砂级和粘粒级对P吸附量分别小于50、46、50和97 mg⋅kg-1，Cd2+吸附量低于未处理土样，P吸附量大于该数值，Cd2+吸附量高于未处理土样，团聚体吸附磷酸盐对Cd2+吸附量的影响，表现为低P吸附量抑制Cd2+的吸附，高P吸附量促进Cd2+的吸附，即随P吸附量增加Cd2+的吸附量呈波谷形变化；而团聚体吸附磷酸盐后对Cr(Ⅵ)的吸附则表现明显的抑制作用。磷酸盐预处理的团聚体对Cd2+、Cr(Ⅵ)吸附量大小顺序均为粘粒级>砂粒级>粗粉砂级>粉砂级，与有机质和游离氧化铁的含量顺序一致。团聚体对Cd2+的吸附过程分为快、慢两个阶段，快吸附阶段用一级动力学方程拟合最佳，而慢吸附时段用扩散方程和Elovich方程拟合最佳，表明吸附过程由不同的吸附因素控制。团聚体吸附磷酸盐后对Cd2+的吸附动力学常数增大。团聚体对Cr(Ⅵ)的吸附过程无明显快、慢阶段，对Cr(Ⅵ)吸附的整个过程用双常数速率方程和Elovich方程进行描述最佳，团聚体吸附磷酸盐后对Cr(Ⅵ)的吸附动力学常数减小。磷酸盐对土壤中重金属吸附的影响与金属离子类型以及磷吸附量有关，所以采用磷肥等含磷物质修复重金属污染土壤要注意金属离子的类型和磷肥的施用量。%The different particle size fractions of paddy soil were separated using the low-energy ultrasonic dispersion and siphon sedimentation methods, and the effects of different phosphate concentrations on the characteristics of the adsorption and the adsorption kinetics of cadmium and chromium4+ by aggregates in paddy soil were studied by the constant temperature oscillation method. The results show that the adsorption amount of Cd2+ is lower than that of the untreated soil when the adsorption capacities of phosphate by the sand, coarse silt, silt and clay are less than 50, 46, 50 and 97 mg·kg-1, respectively, and the adsorption amount of Cd2+ is more than that of the untreated soil when the adsorption amounts of phosphate are more than the above values, respectively, indicating that the low adsorption of phosphate inhibits the adsorption of Cd2+, while the high adsorption of phosphate favors the adsorption of Cd2+. With the increase of phosphate adsorption, the adsorption of Cd2+ changes in a trough shape variation. However, the aggregates inhibit the adsorption of Cr(Ⅵ)significantly after the adsorption of phosphate. The adsorption amounts of Cd2+ and Cr(Ⅵ) by the aggregates pretreated by phosphate are in the order: cosmid > sand > coarse silt > silt, which is the same as the order of the concentrations of organic matter and free iron oxide. The adsorption process of Cd2+ by the aggregates is divided into two stages, which are the fast period and the slow period. In the fast adsorption period, the adsorption is fitted best by first-order kinetic equation, while in the slow period, it is fitted best by the diffusion equation and the Elovich equation, suggesting that the adsorption process is controlled by the different adsorption factors, and the adsorption kinetic constant of Cd2+ increases when the aggregates adsorb phosphate. The adsorption process of Cr(Ⅵ) by the aggregates does not have the fast and slow periods, and the adsorption of Cr(Ⅵ) by the aggregates can be best described by the double constant rate equation and the Elovich equation, and the adsorption kinetic constant of Cr(Ⅵ) decreases after the aggregates adsorb phosphate. The effect of phosphate on the adsorption of heavy metals in the soil was related to the types of metal ions as well as the adsorption amount of phosphate. Therefore, the types of metal ions and application amount of phosphate fertilizer should be paid attention to during the restoration of the heavy metal contaminated soil using the phosphate fertilizer.
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