[Objective]The research aimed to provide scientific basis for the control and the remediation of soil pollution. [Method] Transportation and form transformation of water-soluble cadmium in red soil were simulated by virtue of laboratory soil column tests. [ Result ] Exotic Cd entered soil concentrated mostly on the stratum in depth 0-15 cm and hadn' t migrated on the stratum at unsaturated condition in depth 15-30 cm after ninety days. Water-soluble cadmium added to soil were rapidly transformed to other forms. Exotic Cd mainly existed in exchangeable fraction, secondly existed in residual fraction, Fe/Mn oxide bounded fraction,water fraction, carbonate fraction, organic bound fractionin depth 0 -15 cm after thirty days. In following sixty days, the percentage of exotic Cd fraction varied little with time. The quantities of exchangeable fraction Cd were 76.55% and 72. 31%. [ Conclusion ] Exotic Cd hadn't changed into more stable fractions after ninety days, which had potential harm for soil-plant system. The absorption mechanism on Cd of red soil mainly existed in ion exchange and eomplexation.%[目的]为污染土壤的控制和修复治理提供科学依据.[方法]采用实验室土柱法,研究外源水溶性镉在红壤中的迁移和形态转化.[结果]在非饱和水分条件下,外源水溶性镉进入红壤90d后并未向15 ～ 30 cm土层迁移,而是集中在0～15 cm层次;外源水溶性镉进入红壤(0～15 cm)30 d后水溶态镉迅速向其他形态转化,其形态分布以交换态为主,其次为残渣态、铁锰氧化物态、水溶态、碳酸盐结合态、有机结合态.在其后的60d内,外源Cd各形态的百分比随时间的变化幅度较小,其中交换态镉分别占总量的76.55％和72.31％.[结论]绝大部分外源Cd进入红壤90d后未转化为相对稳定的形态,对土壤—植物系统的污染存在着潜在的危害.红壤对外源水溶性镉的吸附主要通过离子交换和络合作用.
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