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This article in JEQ

  1. Vol. 34 No. 6, p. 2167-2173
     
    Received: Oct 28, 2004


    * Corresponding author(s): ythiry@sckcen.be
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doi:10.2134/jeq2004.0406

Rhizospheric Mobilization and Plant Uptake of Radiocesium from Weathered Micas

  1. A. Gommersa,
  2. Y. Thiry *a and
  3. B. Delvauxb
  1. a Radiation Protection Research Unit, Radioecology Section, SCK•CEN, Foundation of Public Utility, Boeretang 200, 2400 Mol, Belgium
    b Unité Sciences du Sol, Université catholique de Louvain, Place Croix du Sud 2/10, 1348 Louvain-la-Neuve, Belgium

Abstract

Potassium depletion in the soil solution around plant roots promotes the root uptake of radiocesium. However, it can also induce the transformation of mica through the release of interlayer K. In bulk soil, the formation of frayed edge sites (FES) with a high selectivity for Cs adsorption is usually related with mica weathering. We studied the effect of K level in the nutrient solution on the root-induced weathering of phlogopite as well as on the root uptake of radiocesium by willow (Salix viminalis L. var. Orm). The willows were grown for 7 wk in column lysimeters filled with a quartz–phlogopite mixed substrate continuously irrigated with nutrient solutions differing in K concentration (0–2 mM). From a potassium supply of 0.4 mM downward, we observed a decrease in root uptake of potassium as well as an increase in (i) potassium release from phlogopite, (ii) degree of transformation of phlogopite into vermiculite, and (iii) root uptake of radiocesium. Increasing K depletion had thus two effects: a decrease of the root uptake of potassium and an increase of phlogopite weathering in the rhizosphere, both of which promoted the root uptake of radiocesium.

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