Natural radioactivity measurements in agricultural soil, fertilizer and crops in some specific areas of Kingdom of Saudi Arabia

Abstract

High Purity Germanium (HPGe) detector gamma-ray spectrometry with 500 cc Marinelli beaker geometry was used for radioactivity measurement in some specific areas of Kingdom of Saudi Arabia (KSA). The detection limits of ²¹⁰Pb, ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K in soil, fertilizers, and vegetables lie mostly below 1 Bq/kg. The activity concentrations of ²³⁸U and ²²⁶Ra in local phosphate fertilizers were measured in the range of 236.8–879.0 Bq/kg and 101.5–297.0 Bq/kg, respectively. The respective activity concentrations of ²³⁸U and ²²⁶Ra measured in one charge of German phosphate fertilizer are in the range of 552.7–790.0 Bq/kg and 280.6–317.0 Bq/kg. The activity concentrations of ²³²Th are assessed to have maximum values up to 2.24 Bq/kg in locally manufactured phosphate fertilizers. Local urea exhibited concentration level (Bq/kg) of ²¹⁰Pb, ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K below the detection limit. Mean values of activity concentrations of ²³⁸U in agricultural soil of Wadi Fatima, Taif, Hada Al-Sham, Madina City and Abyar Al-MashiMadina are 21.7 ± 3.24, 38.2 ± 4.1, 17.6 ± 2.1, 34.3 ± 3.5 and 32.7 ± 2.4 Bq/kg, respectively. The respective mean of ²²⁶Ra activity concentrations in those areas are 12.16 ± 1.16, 20.2 ± 1.33, 11.21 ± 0.4, 21.4 ± 1.7 and 21.0 ± 1.22 Bq/kg. The specific activity of ²³²Th in the respective areas has been measured as 12.6 ± 1.3, 25.3 ± 0.8, 11.5 ± 0.9, 20.4 ± 2.4 and 20.0 ± 1.2 Bq/kg. Activity concentrations of ²¹⁰Pb, ²³⁸U, ²²⁶Ra and ²³²Th in the vegetable samples are mostly found in the range of 0.37 Bq/kg to 37.8 Bq/kg. The ⁴⁰K specific activity lies in the range of 44.4–196 Bq/kg. The calculated absorbed dose rates in the representative locations are 24.07–53.28 nGy/h.