铊的水地球化学及环境影响

铊(Tl)是一个典型的毒害金属元素,其对哺乳动物的毒性高于Hg、Cd、Cu、Pb、Zn等元素。Tl在自然水体中存在两种氧化状态:Tl+和Tl3+,通常主要以Tl+形式存在。Tl+易随地下水或地表水的流动而迁移到更远的距离,但在较强的氧化环境中,Tl+能够氧化成Tl3+形成Tl(OH)3的沉淀,可以制约水环境中Tl的总含量。Tl可以通过饮用水进入人体,其中Tl+在人体的酶化反应过程中可以置换K+,并与酶产生很强的亲和力,从而诱发Tl的毒害效应。活性铝净化法、离子交换法和NaCl溶液可以用来去除饮用水中的Tl。基于Tl的毒害性,Tl所产生的水环境问题应该引起重视。

HYDROGEOCHEMISTRY OF THALLIUM AND ITS ENVIRONMENTAL IMPACTS

Thallium is a typical toxic metal, and is more toxic to mammals than mercury, cadmium, lead, copper or zinc. Thallium exists in two oxidation states: Tl~+and Tl3~+, but Tl~+ is generally the dominant species in aqueous environment. Tl~+ may move readily with groundwater or surface water and migrate to a further distance. Under strongly oxidizing conditions, Tl~+ may be oxidized into Tl~(3+), forming the Tl(OH)_3 precipitates. This precipitating process may control the concentrations of total dissolved T1 in waters. When T1 enters human body through drinking water, Tl~+ can substantially substitute for K~+ in body cells and may give a strong affinity to the cell enzyme, so as to trigger the toxicity of thallium. Thallium in drinking water can be eliminated or alleviated by the activated alumina, the ion exchange resins, and the solution of sodium chloride. Due to the high toxicity of thallium, the study of thallium hazard issues related to the aqueous environment should not be neglected.