铊的环境地球化学研究进展

Overview of research about environmental geochemistry characteristics of thallium

铊（Tl）作为一种高毒害性的元素越来越受到人们的关注。大量含Tl矿物的开采和冶炼、化石燃料的燃烧等人类活动,导致Tl及其化合物进入环境,进而通过食物链进入生物体,从而对动植物特别是人类健康造成严重的危害。文章对铊在各环境介质中的存在、迁移、转化,以及Tl的生物效应研究进展进行了概述。Tl在岩石中的平均质量分数为0.5~10 mg.kg-1,在大气中的平均质量浓度为0.22~1.0 ng.m-3,在天然水体中的平均质量浓度为0.001~1.264μg.L-1,在土壤中的平均质量分数为0.01~3.0 mg.kg-1,在植物中的平均质量分数为0.02~0.25 mg.kg-1。大气中的铊可随大气迁移,导致全球Tl污染;土壤中Tl的迁移主要受pH影响,pH越小其迁移能力越强,而水中溶解态的铊迁移能力最强。植物对Tl具有较强的富集能力,而动物实验则表明Tl具有一定的致畸性,可能存在一定的致癌性,并且职业暴露是人体Tl中毒的主要原因。尽管有关有Tl的地球化学以及生态毒理学方面的研究取得了一定的进展,但有关Tl在环境介质之间的界面化学机理、Tl在分子水平上吸附机理、不同形态的Tl在生物体中的致毒代谢机理以及铊的同位素在环境介质中的变化等方面仍有待于进一步的研究。

Thallium has been attracting more and more attention recently due to its high toxicity.Extensive Tl-containing ore mining,smelting,and Tl-containing fossil fuel burning are the major sources of anthropogenic dispersion of thallium in the environment.Thallium pollutants in the environment would enter into living organisms via food chain and pose serious hazards to plants,animals and especially the human beings.In this paper,the thallium research progress in the distribution,migration,transformation between different environmental medium and its bioeffect was comprehensively reviewed.The concentrations of thallium in the rocks,air,natural water,soils,and plants were in the range of 0.5~10 mg·kg-1,0.22~1.0 ng·m-3,0.001~1.264 μg·L-1,0.01~3.0 mg·kg-1 and 0.02~0.25 mg·kg-1,respectively.Thallium could transport with air leading to global thallium contamination.The transference of thallium in the soil depends on the pH of the soil,and the higher value of pH,the stronger capability of thallium＇s transference.Dissolved thallium in water is able to transport far away,and is easily enriched by plants.Animal experiments revealed that thallium might have teratogenicity and carcinogenicity at some aspect.Occupational exposure was the main reason for human poisoning.Although there has been some progress in thallium environmental geochemistry and ecotoxicology,further investigation should be enhanced in some more aspects,such as its mechanism of the interfacial chemistry in different environmental medium,of the adsorption at molecular level,and of the organism＇s toxicity metabolism with different species of thallium,and the varieties of thallium＇s isotopes in different environmental medium.