外源镉污染及水溶性有机质对土壤中Cd形态的影响研究

Effect of Exogenous Cadmium Pollution and Dissolved Organic Matter on Forms of Cd in Soil

通过盆栽实验,考察了加入不同量的外源性镉、水溶性有机质对土壤镉的各种形态和对藤菜吸收镉的影响。试验结果表明,随外源镉污染量的增加,可溶态镉由20mgkg-1污染水平的6.277mgkg-1增加为225mgkg-1污染水平的24.80mgkg-1、有机结合态镉含量由150mgkg-1污染水平的0.667mgkg-1增大为225mgkg-1污染水平的4.44mgkg-1,可直接被植物所吸收的水溶态镉的增大对植物的危害加大。随着DOM加入量的增加,水溶性镉的含量逐渐增加,加入100mlDOM时水溶性镉所占比例上升到39.4%;水溶性有机质的加入增加了土壤镉的生物有效性,并随水溶性有机质体积的增加而增加。藤菜对镉的吸收量随水溶性有机质加入体积的增加而增加,加入100mlDOM时藤菜中镉含量由13.83mgkg-1增加为19.17mgkg-1。

A pot experiment is performed to understand the effect of Cd and the dissolved organic matter （DOM） on the forms of Cd and the absorbed Cd by vegetables in different levels. It was indicated that the bioavailability of Cd increases with the increase of Cd pollution in soil. The soluble state Cd increased from 6.277 mg kgq to 24.80 mg kgq as Cd content in soil increased from pollution 20 mg kg^-1 to 225 mg kg^-1. The organic state increased from 0.667 mg kg^-1 （Cd pollution of 150 mg kg^-1） to 4.44 mg kg^-1 （Cd pollution of 225 mg kg^-1）. The hazard on plant became serious with the increase of soluble state Cd. The content of soluble state Cd increased with the increase of DOM volume, which increased 39.4% as the volume was 100 ml. DOM promoted the bioavailability of Cd in soil, and the bioavailability increased as the added dissolved organic matter increased. The absorbed amount of Cd in water convovulus was augmented as the dissolved organic matter increased, which increased from 13.83 mg kg^-1 to 19.14 mg kg^-1 as volume of DOM increased from 0 ml to 100 ml.