INVESTIGATION AND EVALUATION OF RADIOLOGICAL RISK ASSOCIATED WITH NITROGENOUS FERTILIZER IN NIGERIA USING GAMMA RAY SPECTROMETER
Keywords:
Urea fertilizer, natural radionuclides, ionizing radiation, gamma ray spectrometerAbstract
Urea fertilizer is considered as the most important nitrogenous fertilizer sold in Nigerian market. The use of urea fertilizers to enhance growth of vegetable crops, flowers and lawn has recently drawn public concern in the aspect of its contribution to environmental radioactivity. Potential radiological risk due to the activity concentration of40K, 226Ra and 232Th in urea fertilizer samples collected from local supplier in different locations in southwestern Nigeria was determined using NaI(Tl) gamma ray spectrometer detector. Results of analyses showed that activity concentration of 40K, 226Ra and 232Th in urea fertilizer ranged from 154.3±7.9 to 2907±18.8 ; 7.5±5.2 to 23.4±10.7 and 28.2±3.8 respectively with total mean values of 183.6±9.6 , 13.2±5.8 and 38.3±10.0 respectively which were lower than the corresponding maximum safety limit for soil. Furthermore, estimation of absorbed dose rate in air and outdoor annual effective dose were below the standard safety limit 60 and 0.07 respectively.. External and internal hazard indices as well as alpha index were determined with results less than unity (1.0) as the standard safety limit; an indication that there is no radiation risk associated with the use of investigated urea fertilizer samples, therefore, samples investigated were radiologically safe to users of the fertilizer product.