THE DISTRIBUTION OF U, TH AND RA-226 DERIVED FROM THE PHOSPHATE FERTILIZER INDUSTRIES ON AN ESTUARINE SYSTEM IN SOUTHWEST SPAIN

This paper reports an extensive study of the presence of natural radio activity around a phosphate fertilizer factory complex situated in an estuarine area of southwest Spain. The study has concluded that the wa stes from such industries are the cause of the enhancement of natural radioactivity in the immediate environment. Thus, significantly high l evels of U- and Th-isotopes and Ra-226 are detected in water and sedim ent samples collected in this area. These conclusions based on the enh anced isotopic concentrations are further supported by the measured U, Th and Ra isotopic activity ratios being quite different from any obs erved elsewhere in undisturbed estuaries. These isotope activity ratio s appear to be very sensitive indicators of waste disposal practices i n such environments.