The application of phosphogypsum in agriculture and the radiological impact.
Radium-226 in phosphogypsum produced in a phosphate industry, SICNG operating at Thessaloniki, Northern Greece since May 1966, varied from 261 to 688 Bq kg(-1) (mean value 508 Bq kg(-1)). This radionuclide in soil tilled with phosphogypsum used for agricultural purposes varied from 50 to 479 Bq kg(-1) (average 205 Bq kg(-1)), while in the regular soil of cultivated fields it varied from 37 to 54 Bq kg(-1) (average 48 Bq kg(-1)). Radium-226 in rice originated from cultivated fields tilled with phosphogypsum or not varied from 0.36 to 1.98 Bq kg(-1) (average 1.53 Bq kg(-1)) with the higher values observed in samples originated from cultivated fields tilled with phosphogypsum. Radium-226 transfer factors, TF, from soil tilled with phosphogypsum to plants for the case of rice varied from 6.5 x 10(-3) to 2.0 x 10(-2) (geometric mean: 1.1 x 10(-2)). A mean (226)Ra content in rice 1.53 Bq kg(-1) results in a daily intake of (226)Ra by humans in Greece 0.0084 Bq day(-1) leading to an annual effective dose for adults 0.86 microSv y(-1) which is much less in contributing to the average exposure to natural radiation sources (2.4 mSv y(-1)) and particularly to the part due to ingestion (0.29 mSv y(-1)). It is necessary to continuously control (monitoring) (226)Ra in phosphogypsum before any use for agricultural purposes.
Papastefanou
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Aristotle University of Thessaloniki, Atomic and Nuclear Physics Laboratory, Thessaloniki 54124, Greece. papastefanou@physics.auth.gr
Stoulos
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Ioannidou
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Manolopoulou
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M
D000328:Adult; D000383:Agriculture; D002133:Calcium Sulfate / Q000737:chemistry*; D018556:Crops, Agricultural / Q000528:radiation effects*; D005308:Fertilizers; D006115:Greece; D006801:Humans; D012275:Oryza / Q000737:chemistry / Q000528:radiation effects; D010758:Phosphorus / Q000737:chemistry*; D011883:Radium / Q000032:analysis*; D012990:Soil Pollutants, Radioactive / Q000032:analysis
D005308:Fertilizers; D012990:Soil Pollutants, Radioactive; C077769:phosphogypsum; D010758:Phosphorus; D011883:Radium; D002133:Calcium Sulfate