Uranium diffusion and time-dependent adsorption-desorption in soil: A model and experimental testing of the model
Uranium diffusion and time-dependent adsorption-desorption in soil: A model and experimental testing of the model
复制标题
土壤中铀扩散和时间依赖性吸附-解吸：模型和模型的实验测试
DOI：
10.1111/ejss.12814
复制
发表时间：
2019
影响因子：
4.2
通讯作者：
Darmovzalova J
中科院分区：
文献类型：
--
作者：
Darmovzalova J
过去大多数关于铀在环境中的迁移和反应的研究关注的是地下水污染，而不是植物或土壤生物群的吸收，这两种情况都是在小得多的时间和距离尺度上进行的。我们开发和测试了一个模型，U在土壤中的扩散和反应，在适合植物根系吸收的尺度，基于我们在早期的论文开发的模型。该模型考虑了土壤溶液中铀与羟基、碳酸盐和有机配体的形态，以及与土壤固体吸附反应的性质和动力学。模型预测进行了比较，实验测得的浓度-距离曲线的U在土壤中调整到不同的pH值和CO2压力。使用模型输入参数测量或以其他方式独立于浓度-距离曲线估计，获得了观察到的和预测的曲线之间的极好的一致性，表明该模型是对系统的正确描述，并且允许所有重要过程。的U吸附和解吸的扩散通过土壤的时间尺度的动力学的重要性被突出。结果进行了讨论，在吸收U的植物根系，重点我们建立了一个与植物根系吸收相关的土壤中U扩散和反应模型，并将模型与实测扩散曲线进行了比较，结果表明模型与实测扩散曲线吻合良好。在振荡悬浮液或流通系统中测量的反应动力学可能会产生误导。
Most past research on uranium (U) transport and reaction in the environment has been concerned with groundwater contamination and not with uptake by plants or soil biota, both of which operate over much smaller time and distance scales. We developed and tested a model of U diffusion and reaction in soil at scales appropriate for uptake by plant roots, based on a model we developed in an earlier paper. The model allows for the speciation of U with hydroxyl, carbonate and organic ligands in the soil solution, and the nature and kinetics of sorption reactions with the soil solid. The model predictions were compared with experimentally measured concentration–distance profiles of U in soil adjusted to different pHs and CO2pressures. Excellent agreement between observed and predicted profiles was obtained using model input parameters measured or otherwise estimated independently of the concentration–distance profiles, showing that the model was a correct description of the system and all important processes were allowed for. The importance of the kinetics of U adsorption and desorption for the timescale of diffusion through the soil is highlighted. The results are discussed in terms of the uptake of U by plant root systems, as modelled in the earlier paper.HighlightsWe developed a model of U diffusion and reaction in soil on scales relevant to uptake by plant roots.We tested the model against measured diffusion profiles and obtained excellent agreement.The kinetics of U adsorption–desorption reactions are important.Reaction kinetics measured in shaken suspensions or flow‐through systems are likely to be misleading.