Natural radioactivity levels and heavy metals in chemical and organic fertilizers used in Kingdom of Saudi Arabia

The present work deals with identifying and determining the activity levels of natural occuring radionuclides, 226Ra and 232Th series, their decay products and 40K, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single super-phosphate SSP and triple super-phosphate,TSP) and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The gamma-ray spectrometer consists of NaI(Tl) detector and its electronic circuit was used for measuring γ-ray spectra. The ranges of radioactivity levels of 226Ra, 232Th and 40K in chemical fertilizers are 51.5±5.2–106.3±7.5, 5.1±1.6–9.9±3.2. and 462.6±21–607.3±14 Bq kg−1, respectively. The activities of 226Ra, 232Th and 40K in natural fertilizers (cow, sheep and chicken) are lower than the activities in chemical fertilizers. The obtained data are compared with available reported data from other countries in literature. The Raeq in chemical fertilizer ranges from 100.37 to 161.43 Bq kg−1 and in organic fertilizer ranges from 34.07 to 102.19 Bq kg−1, which are lower than the limit of 370 Bq kg−1 adopted from . The average heavy metal (Pb, Cd, Ni, Co and Cr) contents of the fertilizers marketed in the Kingdom of Saudi Arabia are also determined and within the limits of those used worldwide. - Highlights: ► Mmeasured activity levels of natural radionuclides in chemical and organic fertilizers used in Saudi Arabia. ► Determined heavy metal (Pb, Cd, Ni, Co and Cr) contents. ► Activity of natural radionuclides in chemical fertilizer higher than in organic fertilizer. ► RAeq in chemical and organic fertilizers ranged between 34.07 and 161.43 Bq kg−1.