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专论

Transport of cadmium in purple soil under simulated submerging conditions and the influencing factors

摘要：研究了在模拟淹水条件下紫色土镉的释放迁移特征及影响因素.结果表明, 土壤初始镉污染水平、水体初始酸度和有机酸组成显著影响土壤镉向水体的迁移释放.土壤初始镉浓度每增加1mg·kg^-1, 淹水平衡后水体中镉的浓度增加0.006—0.007mg·L^-1.当水体初始pH<6时, 镉的释放量随pH的降低呈线性增加, 每降低一个pH单位, 水中镉浓度平均将增加0.06mg·L^-1.水体中多种有机物共存时对土壤重金属的释放存在复杂的交互作用.草酸、柠檬酸、EDTA以及草酸、柠檬酸、富里酸、EDTA共存时显著促进土壤镉的释放;而草酸、柠檬酸、富里酸共存时, 反而抑制了土壤镉的释放.讨论了淹水过程中镉的释放与体系pH、Eh变化之间的关系.

Abstract：Transport characteristics of cadmium in purple soil and the influencing factors were studied under simulated submerging conditions. Results indicated that initial soil cadmium level, water pH and composition of organic acids significantly affected the release of soil cadmium into water. An increase of 1mg·kg^-1 cadmium content in soil cansed an increase of 0.006-0.007mg·L^-1 cadmium released into the solution when equilibrium established; the decrease of initial water pH was linearly correlated with the increase of cadmium released into the solution when pH<6 with a slope of -0.06mg·L^-1 per pH unit; coexistences of organic acids in water showed complicated effects on the transport of cadmium in soil water system, the release of cadmium was significantly promoted when oxalic acid, citric acid and EDTA or oxalic acid, citric acid, fulvic acid and EDTA coexisted in water, while obvious inhibition of cadmium release occurred when oxalic acid, citric acid and fulvic acid coexisted. The release of cadmium in relation to the variation of pH and E h in the system during submerging was also discussed.