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Influence of the nature of clay minerals on the fixation of radiocaesium traces in an acid brown earth-podzol weathering sequence

par Maes, Emmanuel;Iserentant, Anne;Herbauts, Jacques ;Delvaux, Bruno
Référence European journal of soil science, 50, 1, page (117-125)
Publication Publié, 1999-03

Article révisé par les pairs

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Résumé :

The magnitude of radiocaesium fixation by micaceous clay minerals is affected by their transformation, which depends on weathering in soil. The net retention of radiocaesium traces was quantified by sorption-desorption experiments in the various horizons of four sandy soils forming an acid brown earth-podzol weathering sequence derived from sandy sediments and characterized by marked changes in mineral composition. The features of the 2:1 minerals of the four soils, resulting from an aluminization process in depth and a desaluminization process towards the surface, had a strong influence on Cs+ fixation. Beneath the desaluminization front, which deepens from the acid brown earth to the podzol, hydroxy interlayered vermiculite was dominant and the 137Cs+ fixation was the weakest. At the desaluminization front depth, vermiculite was responsible for the strongest 137Cs+ fixation. In the upper layers, smectite appeared in the podzolized soils and the 137Cs+ fixation decreased. The magnitude in Cs+ fixation therefore appeared as a tracer of the transformation process affecting the 2:1 clay minerals in the acid brown earth-podzol weathering sequence. This magnitude was positively correlated with the vermiculite content of the studied soil materials estimated by the rubidium saturation method.