نبذة مختصرة : The main goal of this Project has been the radiological and alimentary assessment of the agriculture use of phosphogypsum (PG), a by-product of the fertilizer industry, as Ca-amendment in reclaimed salt-marsh soils in SW Spain. The work-plan included: PG characterization (concentrations of radionuclide and heavy metals, 222Rn exhalation from PG stacks), experimental field studies attending to the effect of PG in agriculture soils and drainage waters, and studies on soil-to-plant transfer of radionuclides and heavy metals (through both, field and greenhouse studies). PG characterization (PG stacks) FERTIBERIA, a fertilizer factory located in Huelva (SW Spain) owns a non-active PG stack lying in the right bank of the Tinto River. From this PG stack, of about 1 km2 and 8-10 m deep, PG could be extracted for agriculture uses. PG has being traditionally used since late 1970’s as a Ca-amendment for the reclaimed soils from the salt-marsh area of the Guadalquivir River. 222Rn exhalation in this non-active stack has been measured following the USEPA method 115 (adapted for using cylindrical charcoal canisters). Experimental studies conducted in collaboration with the Institute of Biophysics from the University of Salzburg, demonstrated the repeatability and accuracy of the charcoal canister method for the commented determinations. The accuracy was demonstrated against the exhalation chamber method. Finally, experiments with PG columns of different heights demonstrated that the major contribution to Rn exhalation comes from the 0-50 cm horizon. A total of 162 measurements of 222Rn exhalation have been carried out, corresponding to 49 sampling points distributed through three different regions in the stack (1, compacted and dry top surface area; 2, loose –tilled- dry top surface and 3, sides). Three charcoal canisters were placed at each sampling point, covering an area of ~1 m2 . 222Rn exhalation values ( 510 ± 470, 250 ± 270 y 360 ± 170 Bq h-1 m-2 for regions 1,2, y 3, respectively) show high dispersion, but their mean ...
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