The radioactivity measurements in soils and fertilizers using gamma spectrometry technique

摘要

Because of their mineral content, soils are naturally radioactive and one of the sources of radioactivity other than those of natural origin is mainly due to the extensive use of fertilizers. The main aim of this paper is to evaluate the fluxes of natural radionudides in local production of phosphate fertilizers to determine the content of radioactivity in several commercial fertilizers produced in Algeria and to estimate their radiological impact in a cultivated soil even for the long-term exposure due to their application. For these purposes, virgin and fertilized soils were collected from outlying Setif region in Algeria and from phosphate fertilizers used in this area. Gamma spectrometry was exploited to determine activity concentration due to naturally occurring ~(226)Ra, ~(232)Th and ~(40)K in five types of samples (two different sorts of fertilizers, virgin and fertilized soils and well water used for irrigation) taken from Setifs areas. The results show that these radionudides were present in an average concentration of 134.7 ± 24.1, 131.8 ± 16.7,11644 ± 550 Bq/kg for the first fertilizer NPK and 190.3 ± 30,117.2 ± 10.3, 5312 ± 249 Bq/kg for the second fertilizer (NPKs). For the virgin and the fertilized soils, the corresponding values were respectively 47.01 ± 7.3,33 ± 7,329.4 ± 19.7 Bq/kg and 53.2 ± 10.6, 50.0 ± 7,311.4 ± 18.7 Bq/kg. For well water, the values were 1.93 and 0.12 Bq/kg; however the third value was below the Minimum Detectable Activity (MDA). The radium equivalent activity (Raeq) and the representative level index I_(yr) for all samples were also calculated. The data were discussed and compared with those given in the literature.