土壤样品中重金属化学形态模型的发展与应用

土壤中重金属的化学形态与其生物有效性和环境迁移性密切相关。相比于实验室分析手段,化学模型计算具有能揭示化学形态分布全景指纹和具有预测能力的优势。文章综述了天然环境样品中元素化学形态模型的发展、经验性和机理性模型的特征、离子在天然有机质(以NICA-Donnan模型为例)和金属氧化物(以CD-MUSIC模型为例)吸附的先进表面络合模型、建立环境样品机理性模型面临的挑战。重点就天然有机质、金属氧化物和"活性"重金属总量等模型输入值的确定方法作了介绍,并结合镉和砷分别作为金属阳离子和含氧阴离子的典型代表,具体阐述了模型在土壤中重金属元素化学形态分布上的应用。总结了机理性化学形态模型在天然环境样品应用的发展现状,并对模型应用面临的问题和后期的发展做出了展望。

Development and application of chemical speciation models for heavy metals in environmental soil samples

The chemical speciation of heavy metals in soil is closely related to their bioavailability and mobility in the environment. Compared to laboratory analysis, chemical modeling calculation has the advantages of being able to reveal the whole fingerprint of chemical speciation and having the capability to make predictions. In this review, the development of chemical speciation modelling of elements in natural environment is discussed. The characteristics of empirical models and mechanistic models are compared. Advanced surface complexation models for ion adsorption to natural organic matter(using NICA-Donnan model as an example) and to metal oxides(using CD-MUSIC model as an example) are introduced. In addition, the challenges in applying mechanistic modelling to natural environmental samples are summarized. The methods used to obtain input data, i.e. the content of metal oxides, the amount of(active) organic matters and the content of reactive metals are one of the focus of this review. Application of mechanistic models in chemical speciation calculation of heavy metal in soils is illustrated using cadmium(Cd) and arsenic(As) as a representative of cations and oxyanions respectively. In the end, the status of the development and application of mechanistic chemical speciation models for natural environmental samples is concluded, and the problems remaining and future development are visualized.