Etude de la radioactivité naturelle et artificielle dans les fertilisants et le sol de l’Est algérien par spectrométrie gamma.

Abstract

The aim of this study is to evaluate the level of natural radioactivity in seven fertilizers from two different regions, Constantine and Mila in Algeria, and in fertilized and unfertilized soil samples collected at different depths in two pilot and private Algerian farms, from El-Athmania and Ferdjioua, Mila, respectively. Using gamma spectroscopy with a hyper-pure germanium detector (HPGe), a low background configuration and high-resolution. The activity concentration ranges of 226Ra, 232Th and 40K in the soil samples were found at 23.72 ± 2.37 «-ÿ 67.72 ± 7.77, 26.45 ± 0.78 <-ÿ 28.70 ± 0.90 and 178.5 ± 5.64 <-ÿ 290.1 ± 10.5 Bq.kg" , respectively. The results of this current study have been compared with the world mean values of 35, 30 and 400 Bq.kg"1, respectively, specified by the UNSCEAR (2000). The artificial radionuclide, 137Cs was found in all measured soil samples and its mean activity was 2.66 Bq.Kg'1. Additionally, the vertical distribution of 137Cs soil activity concentrations was studied in this current study. It can assumed from the results the decrease of 137Cs as a function of depth. i Concerning radiological risk to human health, the absorbed gamma dose rate (D) in air is estimated to be between 36.23 ± 0.4 and 58.78 ± 2.2 nGy.h'1; the outdoor annual effective dose equivalent (DE) was evaluated to vary from 44.44 ± 0.4 to 69.88 ± 2.7 pSv.y'1, with the arithmetic mean value of 61.43 ± 33.23 pSv.y"1, which is comparable to the worldwide effective dose of 70 pSv.y"1. Also, the Raeq, Hex, Hm and Iy values for all soil samples in this work are lower than the accepted safety limit of 370 Bq.kg'1 and below the unit limit, respectively. The results indicate that the radiation hazard of primordial radionuclides in all soil samples of the regions studied in this current work is not significant. On the other hand, the mean value of the lifetime cancer risk factor for fertilizers studied is 9.45 x 10"4. Two (2) sampling points (FM and TSP) have ELCR values greater than the worldwide average value. These results show that lifetime cancer risk from exposure to these fertilizers for up to 70 years is high in both locations. Therefore, subsequent use of this product for agriculture or for soil remediation studies and other purposes should be discouraged.