Radiological characterization of phosphate rocks, phosphogypsum, phosphoric acid and phosphate fertilizers in Morocco: An assessment of the radiological hazard impact on the environment

Abstract

Radiological characterization of radionuclides contained in the phosphate rocks, phosphogypsum, phosphoric acid, and phosphates fertilizers (DAP, NPS, NPK, TSP, and TAP) in Morocco have been performed to provide a database for the assessment of the environmental and the radiological impacts. The measurements of the activity concentration were carried out using both alpha and gamma spectrometry. Additionally, the radiological parameters such as the gamma radiation hazard index, the internal and external hazard index as well as the outdoor and indoor absorbed gamma dose rates. The corresponding annual effective dose rates and the total excess lifetime cancer risk (ELCR) were also estimated to discuss the radiological hazard.The primary results showed that the activity concentrations of 238U, 234U, and 235U were 174.58–2604.14, 143.03–2765.34 and 8.35–131.64 Bq kg−1, respectively. The 230Th, 232Th and 234Th concentrations found were 239.29–1656.36, 0.68–17.71 and 133.54–2194.27 Bq kg−1, respectively. The specific activities of 226Ra and 40K ranged from <1.97 to 1503.75 Bq kg−1 and from <15.6 to 4710.59 Bq kg−1, respectively. Moreover, the ELCR has been computed and found to be high in phosphate rocks and phosphogypsum, and comply with safety levels in phosphoric acid and most phosphate fertilizers.