Thallium in coal: Analysis and environmental implications

The ecotoxicological importance of thallium stems from its acute toxicity, the effects of which are as harmful to living organisms as those of lead and mercury. The main anthropogenic sources of thallium are the emissions from coal combustion processes, underlining the need to control this element in coal and coal by-products. Despite the threat posed by thallium, very little information has been published on its behaviour in coal-fired power plants or on its modes of occurrence in coal, its mobilisation and its distribution. Although thallium is highly toxic, the environmental risk presented by this element in coal utilisation have been studied to a much lesser degree than in the case of other toxic elements such as lead, cadmium or mercury. The present work addresses the issue of thallium in coal, focussing on its origin, modes of occurrence, the analytical methods commonly used for its determination and its behaviour during coal utilisation for energy production.