基于DGT技术分析土壤镉生物有效性及迁移动力学过程

Analysis of the bioavailability and migration kinetics of cadmium in soil:A DGT-based approach

通过采集分析安徽省石台县仙寓地区61组主要农作物(水稻、茶叶)及其根系土壤样品,基于(DGT)技术研究了典型富硒区土壤中镉(Cd)的生物有效性及其迁移动力学过程,并借助DIFS模型评估土壤Cd的迁移潜力。研究结果表明:土壤DGT-Cd的主要影响因素为pH、有机质、铁锰氧化态Cd。DGT测量的Cd有效态与水稻及茶叶农作物中Cd含量有较好的正相关关系,但水稻的DGT测量生物有效态预测效果要差于茶叶。DGT-Cd和土壤溶液-Cd受土壤性质(有机质、pH和铁氧化物)和土壤易迁移的Cd总量控制。不同土壤R值从高到低的顺序为:pH 4.5~5.5的土壤>pH 5.5~6.5的土壤>pH高于6.5的土壤,pH较低的土壤固相补给更丰富。本研究进一步提升了对研究区土壤中Cd活化的认识,对促进当地富硒农产品安全种植开发具有重要意义。

In each sampling spot,the main crop(rice or tea)and its root zone soil were respectively collected to form a sample pair.By collecting and analyzing 61 sample pairs in the Xianyu area,Shitai County,Anhui Province,the bioavailability and migration kinetics of Cd in typical selenium-rich soil were studied based on DGT technique.The migration potential of Cd in soil was assessed with the aid of the DIFS model.The results showed that the main influencing factors of the bioavailable Cd measured by DGT(DGT-Cd)were pH,organic matter,and Cd bounded by iron-manganese oxides.A positive correlation was shown between the DGT-Cd in soil and Cd content in rice or tea,but the DGT-Cd-based prediction of Cd content in rice is not as good as in tea.DGT-Cd and soil solution-Cd are controlled by soil properties(organic matter,pH,and iron oxides)and the total amount of Cd readily migrating in the soil.The order of the R value of different soils from high to low is:soil with pH 4.5~5.5>soil with pH 5.5~6.5>soil with pH higher than 6.5.The soil with lower pH value has more supply from solid-phase desorption.This study has further improved the understanding of Cd activation in the soil of the study area,which is of great significance to promoting local selenium-rich agricultural products to be grown and developed in a safe way.