有机酸对土壤中镉形态及有效性影响研究

目的通过模拟实验,研究添加低分子量有机酸对污染土壤中镉（Cd）形态分布及生物有效性的影响。方法在模拟镉污染土壤上,添加三种低分子量有机酸：柠檬酸、草酸和苹果酸,采用Tessier连续浸提法测定土壤中各种形态的镉含量;同时用小油菜做植物培养实验,测试镉的生物积累的量。结果添加有机酸对可交换态Cd的影响不大,添加草酸减少了土壤中碳酸盐态Cd的百分含量;添加柠檬酸、苹果酸、草酸都可以使土壤中铁锰氧化态Cd的含量减少,且三种酸之间没有差异;三种有机酸均能显著促进植物对镉的吸收。结论有机酸添加能显著改变土壤中镉的形态分布,提高镉的生物有效性。

Effect of organic acid on Cd forms and availability in soil

Objective： To study the effect of organic acid addition on various chemical forms of cadmium and its availability to plant.Methods： Pot experiment and laboratory culture were carried out and using Tessier sequential extraction method,five chemical speciatios of cadmium were analyzed to investigate the effect of malic acid and citric acid and oxalic acid addition on transformations of Cd forms in brown soils polluted by Cd.Results： The dissolvable Cd content was increased significantly with organic acid addition but exchangeable Cd little affected.The Cd carbonates bounded was increased with the oxalic acid addition.Fe-Mn oxidation Cd declined with the three organic acids addition.Pot experiment showedthat rape Cd content was increased with the three organic acids addition.Conclusion： Three organic acid addition can significantly change Cd forms and enhance Cd absorption in plants.