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, Ra-226 and Th-232 series, their decay products and K-40, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single superphosphate 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(TI) detector and its electronic circuit was used for measuring gamma-ray spectra. The ranges of radioactivity levels of Ra-226, Th-232 and K-40 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 Ra-226, Th-232 and K-40 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 Ra-eq 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 NEA-OECD (1979). 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. (C) 2011 Elsevier Ltd. All rights reserved.