铊在矿物胶体和天然有机质界面上迁移转化行为的研究进展

铊(Tl)是典型的毒害重金属元素之一,对生物体的毒性高于Hg、Cd和Pb等元素。铊在天然水环境相关介质中的背景含量较低,但可通过各种工业活动大量进入水体环境,借由水体迅速迁移扩散,对生态系统造成巨大的环境隐患。本文总结了铊在水体中的分布特征,并重点阐述了铊在矿物胶体和天然有机质(腐殖酸)等界面上迁移转化行为的研究进展。研究表明,铁(氢)氧化物、锰(氢)氧化物均能在一定程度上吸附水体中的Tl(I),铊在一些锰(氢)氧化物表面的吸附行为可能会涉及Tl(I)在矿物表面的氧化还原机制。矿物表面对铊离子的吸附作用不仅与矿物的组成成分有关,还可能与矿物组成成分的晶型结构密切相关。天然有机质对铊迁移转化影响作用的研究目前主要偏重天然腐殖酸对铊的络合作用。因此,要加强的研究铊分别在不同种类、不同晶型的矿物和不同类型的天然有机质界面上的迁移转化行为,并借助高精度的价态和结构分析手段从分子水平上探讨其迁移转化机理。了解铊在水体中的迁移转化有助于深入认识铊的环境地球化学行为,并为研究铊的污染治理提供理论基础。

Overview of the Research on Transfer and Transform Behavior of Thallium on the Interface between Mineral and Natural Organic Matter

Thallium(Tl) is a typical toxic heavy metal,with higher toxicity than Hg,Cd,Pb.The content of Tl is comparatively low in related mediums of natural aquatic systems.However,a large amount of Tl enters into the hydro environment due to various industrial activities,which seriously endangers the ecosystems.This paper summarized the recent advance on the distribution of Tl in waters and the transfer and transformation behavior of Tl.The main focus is on the up-to-date research on transfer behavior of Tl in water systems with mineral colloid and natural organic matter(humic acid).It was found that the Fe-(hydr)oxide and Mn-(hydr)oxide could adsorb Tl from water to some extent,and the adsorption of thallium on some Mn-(hydr)oxide minerals might be attributed to the oxidation of Tl(I) on the mineral surface.The adsorption of Tl could be affected not only by the different mineral components,but also by the crystal structure of the mineral.The effect of natural organic matter on the behavior of Tl transform and transfer has now been mainly focused on that of natural humic acid.Therefore,further research should be enhanced in the respect of interfacial behavior of Tl with a variety of different mineral colloids,different mineral crystal structures and different kinds of natural organic matter,and the interfacial transfer mechanism of Tl with aid of advanced technique to analyze oxidation state and structure at molecular level.The understanding of Tl transfer behavior in aquatic environment is one of the key points for understanding geo-environmental chemistry of Tl,and provides theoretical basis for preventing Tl pollution.