Enhanced radioactivity in an estuarine system at the southwest of Spain

A study of the distribution of natural radionuclides released by a phosphate rock processing factory located in the estuarine system composed by the confluence of the Odiel and Tinto rivers in the Atlantic Ocean has been carried out. This study includes the Odiel river basin, which receives the wastes from this factory, and the Odiel marsh which is highly affected by the influx of Odiel river waters. The study has concluded that the wastes from this industry are the cause of the enhanced radioactivity in the estuarine environment. Moreover, the study of six sequentially leached fractions of bottom sediments has shown that the total U is located in the non-residual fractions of the sediments, coprecipitation with amorphous ferro-manganese oxy-hydroxides being the main process of U incorporation from the water column to bottom sediments. The study of the radioactive concentration in Spartina Densiflora plants from the Odiel marsh has also shown that the discharges from the industries reach the vegetation of the area. (author)