Speciation of actinides after plant uptake

Abstract

Actinides have high hazardous potential. They are non-essential elements. Besides the natural occurring elements such as uranium, thorium and their decay products, the transuranium elements neptunium, plutonium, americium and curium are important actinide elements to be considered in nuclear waste management and nuclear accidents. It is known that the toxicity of an element depends strongly on its speciation and therefore also on its bioavailability. As an example, the toxicity of uranium decreases in the series uranyl phosphates > uranyl citrates > uranyl carbonates. This underlies the importance of knowledge about the element speciation of actinides. Plants are an important part within the food chain. Therefore, knowledge about the speciation of actinides in these organisms may evince hazards after consumption and ways to protect living beings. Nevertheless, the knowledge about actinide speciation in organisms including plants is very rare. Most of publications up to now deal with transfer factors. A few publications point out that actinides exist often in a phosphate form. Nevertheless, during uptake, other binding forms may play important intermediates. Also, information about binding forms of actinides in storage compartments inside plant cells helps to estimate the hazardous potential. Uranium, americium and curium show luminescence properties, which can be used for the determination of the binding of these elements. Therefore, it can be expected that the knowledge increases in the next decade.