The application of phosphogypsum in agriculture and the radiological impact

Abstract: Radium-226 in phosphogypsum produced in a phosphate industry, SICNG operating at Thessaloniki, Northern Greece since May 1966, varied from 261 to 688Bqkg−1 (mean value 508Bqkg−1). This radionuclide in soil tilled with phosphogypsum used for agricultural purposes varied from 50 to 479Bqkg−1 (average 205Bqkg−1), while in the regular soil of cultivated fields it varied from 37 to 54Bqkg−1 (average 48Bqkg−1). Radium-226 in rice originated from cultivated fields tilled with phosphogypsum or not varied from 0.36 to 1.98Bqkg−1 (average 1.53Bqkg−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 6.5×10−3 to 2.0×10−2 (geometric mean: 1.1×10−2). A mean 226Ra content in rice 1.53Bqkg−1 results in a daily intake of 226Ra by humans in Greece 0.0084Bqday−1 leading to an annual effective dose for adults 0.86μSvy−1 which is much less in contributing to the average exposure to natural radiation sources (2.4mSvy−1) and particularly to the part due to ingestion (0.29mSvy−1). It is necessary to continuously control (monitoring) 226Ra in phosphogypsum before any use for agricultural purposes. [Copyright &y& Elsevier]