巯基化凹凸棒石对水稻土中镉钝化效应的动态变化特征

为了探究巯基化凹凸棒石作为钝化剂在土壤-水稻体系中对镉的钝化效应的动态特征规律,选取湖南和四川典型镉污染水稻土,分别以两个品种水稻为模式作物开展盆栽试验,在水稻生育期代表性阶段开展土壤-植物协同采样,并结合土壤培养实验,重点关注土壤理化性质和水稻各组织镉含量变化.研究发现,巯基化凹凸棒石以剂量1 mg·kg-1和2 m...

Dynamic characteristic of the immobilization effect of thiolated attapulgite on cadmium in paddy soil

To explore the dynamic characteristics of thiolated attapulgite (TA), an immobilization amendment in soil-rice system, typical cadmium (Cd) contaminated paddy soils in Hunan and Sichuan provinces were selected to conduct pot experiments with two rice varieties as model crops. Soil-plant collaborative sampling and soil culture experiments were carried out at the representative stage of growth period, primarily aiming to understand the dynamic changes in the physical and chemical properties of soils and Cd concentrations in various tissues of rice plant affected by TA. The results showed that the Cd concentrations in the root, stem, and leaf of rice in tillering stage decreased by more than 40% and the available Cd in soil decreased by 35.80%~55.08% after TA is applied at the dosages of 1 mg·kg^-1 and 2 mg·kg^-1, respectively. Its rapid and significant immobilization effect was stable at heading stage and maturity stage. The maximum reduction of Cd in grains were 76.65% and 64.67%, respectively. The immobilization process of TA on available Cd in the soil can be interpreted with the second-order kinetic equation with fast immobilization rate. The reaction equilibrium was reached in 3 days in the high-dose group. TA had no significant effect on soil pH in each collaborative sampling period, but slightly increased soil redox potentials. Additionally, it increased the soil total sulfur and available sulfur concentrations, enriched the iron and sulfur concentrations in rice root and root surface at tillering stage, and reduced the bioconcentration factors of Cd in rice root and the transfer factors from root to stem. The formation of iron plaque on the surface of rice roots at the tillering stage inhibited the uptake of Cd by rice roots from soil and the transport of Cd to shoots. This research showed that TA had a rapid and lasting immobilization effect on Cd in rice-soil system.