Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Dalian Hydrological Bureau of Liaoning Province, Dalian 116023, China.
Sci Total Environ. 2022 Feb 10;807(Pt 3):151039. doi: 10.1016/j.scitotenv.2021.151039. Epub 2021 Oct 18.
The adsorption/desorption of arsenic (As) in agricultural soils is of utmost importance for the evaluation of its kinetic release and potential of entering the food chain by uptake of crops. However, the mobility of As in soils is closely related to the migration behavior of soil phosphorus (P) due to their chemical similarity. Here, the distribution and desorption kinetics of As and P in four different types of farmland soils were simultaneously estimated by cerium oxide-based diffusive gradients in thin films technique (CeO-DGT) coupled with dynamic model of DGT induced fluxes in soils (DIFS). CeO-DGT was deployed in the soils over 400 h to investigate the interactions between As and P for their migration behaviors. The accumulated masses of As in the DGT devices showed reverse orders with those of P among the four soils, indicating their competitive adsorption on soil solids. The distribution coefficients (K) for the labile As and P derived from the DIFS model were mutually exclusive. Clay in the soil reduced the pool size of the labile As by increasing the irreversible adsorption of As on soil particles. The adsorption rate constants of As were much smaller than P but their desorption rate constants were comparable. Among the four soils, the soil with the highest soil labile As/P molar ratio measured by DGT showed the largest potential of As phytotoxicity. Both As and P could reach the equilibrium of resupply within 0.7- 18 min under DGT depletion, and significant negative correlation was observed between the desorption rate (k) of As and clay content in the soils.
砷（As）在农业土壤中的吸附/解吸对于评估其动力学释放及其通过作物吸收进入食物链的潜力至关重要。然而，由于其化学相似性，As 在土壤中的迁移性与土壤磷（P）的迁移行为密切相关。在这里，通过基于氧化铈的薄膜扩散梯度技术（CeO-DGT）与土壤中 DGT 诱导通量的动态模型（DIFS）同时估计了四种不同类型农田土壤中 As 和 P 的分布和解吸动力学。CeO-DGT 在土壤中部署了 400 小时，以研究 As 和 P 之间的相互作用，以研究它们的迁移行为。在四种土壤中，DGT 装置中积累的 As 质量与 P 的质量呈相反顺序，表明它们对土壤固体的竞争吸附。从 DIFS 模型得出的可利用 As 和 P 的分配系数（K）相互排斥。土壤中的粘土通过增加 As 对土壤颗粒的不可逆吸附，减少了可利用 As 的库容量。As 的吸附速率常数远小于 P，但它们的解吸速率常数相当。在四种土壤中，通过 DGT 测量的具有最高土壤可利用 As/P 摩尔比的土壤显示出最大的 As 植物毒性潜力。在 DGT 耗尽下，As 和 P 都可以在 0.7-18 分钟内达到补给平衡，并且在土壤中解吸速率（k）与粘粒含量之间观察到显著的负相关。
