Fluxes and distribution of natural radionuclides in the production and use of fertilizers

The industries devoted to the production of phosphate fertilizers make use of large amounts of phosphatic rocks, that are enriched in radionuclides from the uranium series. These radionuclides can reach the environment via disposal of by-products and/or liquid effluent releases and thus will constitute a non negligible source to increased radiation doses. Also, a fraction of the radioactivity originally present in the primary mineral will be associated to the commercial fertilizers, being for that some radio-nuclides spread on the tilled soils in considerable amounts.Knowing that, the fluxes of different natural radionuclides in the production process of fertilizers in some chemical factories sited in the South-West of spain has been evaluated trough the determination of 238-U, 234-U, 226-Ra, 210-Po, 228-Ra and 40-K concentrations in primary minerals, by products, liquid effluents, etc. This study together with additional determinations carried out in different commercial fertilizers allow us to estimate the radioactive and radiological impact caused for the production and use of these products. 2 refs. (author)