中文摘要：

用添加20 mg.kg^-1镉（Cd）的红壤（pH 4.46）室温淹水培养41 d,研究淹水还原作用对Cd溶解性的影响,同时设置水稻培养试验,在红壤淹水初期（1-11 d）和后期（淹水31-41 d）植入水稻秧苗,以比较不同淹水时段红壤Cd对水稻的有效性。结果表明,红壤淹水后1-25 d水溶性Cd浓度由0.210 mg.L^-1上升到0.254 mg.L^-1,淹水28-40 d水溶性Cd浓度由0.221 mg.L^-1下降到0.092mg.L^-1,在淹水1-11 d和31-41 d水稻茎叶Cd含量分别为48.37和16.25 mg.kg^-1。说明淹水初期红壤Cd活性和生物有效性高于淹水后期。通过红壤淹水过程Fe、Cd溶解性及CEC、阳离子饱和度等的研究,表明红壤淹水后氧化铁的还原溶解作用导致pe＋pH下降和pH上升,由此控制着Cd活性和生物有效性的升降。

英文摘要：

Bioavailability of Cd may be strongly affected by the redox processes in soils after submergence. In this study a red soil （pH 4.46 ） was spiked with 20 mg·kg^-1 Cd and was incubated under submerged condition for 41 days. At the same time, rice seedlings were cultured during the initial （ 1^st- 11^th day ） and later periods （31^st -41^st day） after the soil was flooded in order to study the effect of soil redox processes on the Cd bioavailability. Results showed that the dissolved Cd concentration increased from 0.210 to 0.254 mg ·L^-1 until the 25^th day after submergence, and then decreased from 0.221 to 0,092 mg· L^-1. Cadmium content in rice shoot harvested at the 11^th day and 41^st day of incubation were 48.37 and 16.25 mg· kg^-1, respectively. These results indicated that Cd activity and bioavailability at the beginning of submergence were higher than the later period. Through the research on the solubility of Fe and Cd, CEC and saturation of exchangeable cations of the soil, it was found that the decrease of pe＋pH and the increase of pH were caused by the reductive dissolution of iron oxides, which controlled the variations of the activity and bioavailability of Cd in the red soil.