Institute of Environment and Sustainable Development in Agriculture/Key Laboratory of Agro-Environment, Chinese Academy of Agriculture Sciences/Ministry of Agriculture, Beijing, 100081, China.
The College of Natural Resources and Environment of South China Agricultural University/Key Laboratory of Arable Land Conservation, Ministry of Agriculture, Guangzhou, 510642, China.
Environ Sci Pollut Res Int. 2018 May;25(13):12876-12882. doi: 10.1007/s11356-018-1550-0. Epub 2018 Feb 24.
The mobility of arsenic (As) in soil depends on its sorption/desorption processes on soil particles. Plant uptake locally lowers As concentration in soil pore water, which would trigger resupplies of As from soil solid phase. To better understand the fate of As in soil system after its inputs into soil and its subsequent dynamic processes, diffusive gradients in thin films (DGT) technique along with DGT-induced fluxes in soils (DIFS) model were introduced to study the kinetic information of As in soils, including its response time (T) and resupply rate constant (k). To achieve a series of soils with gradient As level, two different types of soils with similar As level (total As in soil JL is 7.4 mg kg, while in soil BJ is 6.5 mg kg) were collected and amended with exogenous As. Then, DGT deployments were carried out following a period of 90-day soil incubation. The simulated T values in non-amended soil JL and soil BJ were 0.036 and 0.001 s, respectively. The difference may due to the properties of these two soils, including pH values and contents of adsorption materials, such as Fe and Al compounds. After As inputs into soils, the intrinsic rate of As release from the solid phase to the solution phase in As-amended JL soil was much higher than that in non-amended soil. While for soil BJ, a decreasing trend was observed after As spiking. The redistribution of As may responsible for the different variation trends of As kinetics in these two soils after As spiking. The results indicated that the distribution coefficient of As (K) in soil was mainly affected by soil Olsen-P content due to an ubiquitous competition between P and As on soil particles.
砷（As）在土壤中的迁移性取决于其在土壤颗粒上的吸附/解吸过程。植物对砷的吸收会降低土壤孔隙水中的砷浓度，从而引发土壤固相中砷的再次供应。为了更好地了解砷输入土壤后在土壤系统中的归宿及其随后的动态过程，引入了薄膜扩散梯度（DGT）技术以及土壤中 DGT 诱导通量（DIFS）模型来研究土壤中砷的动力学信息，包括其响应时间（T）和供应速率常数（k）。为了获得一系列砷浓度梯度的土壤，采集了两种总砷浓度（土壤 JL 中的总砷为 7.4mgkg，而土壤 BJ 中的总砷为 6.5mgkg）相似但砷浓度不同的土壤，并添加外源砷。然后，在 90 天的土壤培养期后进行 DGT 部署。未添加外源砷的土壤 JL 和土壤 BJ 的模拟 T 值分别为 0.036 和 0.001s，差异可能归因于这两种土壤的性质，包括 pH 值和吸附材料（如铁和铝化合物）的含量。砷输入土壤后，砷在添加砷的 JL 土壤中从固相向溶液相释放的固有速率远高于未添加外源砷的土壤。而对于土壤 BJ，添加外源砷后，砷的释放速率呈下降趋势。砷的再分配可能是导致这两种土壤在添加外源砷后砷动力学变化趋势不同的原因。结果表明，土壤中砷的分配系数（K）主要受土壤奥尔森磷（Olsen-P）含量的影响，因为磷和砷在土壤颗粒上普遍存在竞争。
