Soil to plant transfer of 226Ra in a marsh area: Modelling application

The Odiel river forms an estuarine system which surrounds a large marsh area. A phosphate fertilizer processing complex releases its wastes into the estuary. The presence of 226Ra in soils and plants (Spartina Densiflora) from the marsh has been investigated. Concentrations up to 700 and 15 mBq g-1 have been detected in soil and plant samples, respectively. Soil to plant concentration ratios have been calculated and some activity ratios have also been investigated. A model which is able to simulate the dispersion of radionuclides in the marsh has been applied. The model includes the exchange of radionuclides between water and the solid phase (suspended matter and bottom sediments) and the transfer of radionuclides to the plants. Model results are, in general, in good agreement with measurements.