Radioactivity in soils and various foodstuffs from the Gediz River Basin of Turkey

The aim of this study is to determine the enhancement in natural radioactivity level of soils due to the usage of fertilizers, particularly phosphate fertilizers in agricultural lands of Gediz River basin, Western Turkey. In addition, the activity concentrations of naturally occurring radionuclides in some vegetables collected from the same lands were investigated in order to assess any contribution to the effective internal dose after ingestion. Radioactivity concentrations of natural radionuclides, namely Ra-226, Th-232 and K-40, in fertilized, non-fertilized soils and vegetables were measured by NaI(TI) gamma spectrometer in order to assess the implications of the extended use of phosphate fertilizers in agriculture in recent years. Activity concentration of Po-210, an alpha particle emitter, were also analysed using a ZnS(Ag) alpha counter after electrodeposition process. In addition, physical and chemical characteristics of soil samples were investigated and analysed for any correlation between the soil characteristics and their radionuclide contents. In vegetables collected from agricultural fields of the basin the ranges of the relative activity concentrations of K-40, Ra-226, Th-232 and Po-210 are found to be 491.62-2324.51, 15.96-52.80, ND-10.54 and 8.40-22.20 Bq kg(-1), respectively. In soils of agricultural lands, where vegetables are collected, the activity concentrations of K-40, Ra-226, Th-232 and Po-210 are 325.89-530.52, 46.05--68.83, 9.29-50.57 and 36.75-56.70 Bq kg(-l) respectively. For non-fertilized fields, activity concentrations of soils are found to be within 240.40-403.09 Bq kg(-1) for K-40, 35.61-62.64 Bq kg(-1) for Ra-226, 7.40-38.53 Bq kg(-1) for Th-232 and 32.50-41.14 Bq kg(-1) for Po-210. (C) 2007 Elsevier Ltd. All rights reserved.