Natural radıoactıvıty measurements ın soıl samples at Isparta provınce

Living things are exposed to ionizing radiation from artificial and/or natural sources in their environment throughout their lives. More than 80% of the annual effective dose received is due to ionizing radiation of natural origin. Radioactive substances in soil can cause serious effects on human health. Determining radioactivity levels in soil is of great importance for human health, agricultural production, environmental protection and nuclear safety. Regular monitoring and evaluation are necessary to reveal possible risks and take the most appropriate precautions. In this study, it was aimed to radiologically investigate the Isparta region in question, based on literature information that gamma dose rate levels and indoor atmospheric radon (222Rn) concentrations in the city center of Isparta are above the country and world averages. Within the scope of this thesis, firstly, activity concentration measurements of 226Ra, 232Th, 40K and 137Cs radionuclides were performed for soil samples taken from 72 measurement points in Isparta city center and 12 districts. A gamma spectrometer with a high-purity germanium (HPGe) detector was used for the measurements. It was found that the activity concentration levels in the soil samples ranged from 4.08±0.39 Bqkg-1 to 69.84±1.50 Bqkg-1 for 226Ra, ranged from 2.63±0.28 Bqkg-1 to 65.66±1.49 Bqkg-1 for 232Th, ranged from 4.48±3.17 Bqkg-1 to 452.38±9.67 Bqkg-1 for 40K and ranged from 0.28±0.16 Bqkg-1 to 19.10±0.66 Bqkg-1 for 137Cs. The provincial averages were; 15.69±0.72 Bqkg-1 for 226Ra, 15.40±0.78 Bqkg-1 for 232Th, 210.60±6.22 Bqkg-1 for 40K and 3.44±0.31 Bqkg-1 for 137Cs. On the other hand, the activity concentration averages of 226Ra, 232Th, 40K and 137Cs in Isparta city center were; 47.55±1.22 Bqkg-1, 44.35±1.24 Bqkg-1, 407.67±8.85 Bqkg-1 and 2.02±0,43 Bqkg-1, respectively. It was revealed that the average values for the province were below the national and world averages, but the 226Ra and 232Th activity concentration levels in the soil of the central district exceeded the country and world averages. Statistical analyses of the data for 226Ra, 232Th, 40K and 137Cs activity concentrations obtained from 13 districts were performed using SPSS (Statistical Package for the Social Sciences) 29.0 program. Since the number of data was less than 50 for each district measurement, the Shapiro-Wilk test was applied for the normality test. Since the p-values were greater than 0.05 for each group, it was concluded that the data had a normal distribution. In the analyses performed using the one-way ANOVA test, it was determined for the 226Ra, 232Th and 40K data that there was a statistically significant difference (p<0.05) among the district measurements. However, it was found that the p-value for 137Cs measurements was greater than 0.05, indicating a lack of statistical significance among the measurements of the districts. To determine which district measurements there were differences, the analysis of variance was applied to the 226Ra, 232Th and 40K data by using the Tukey test that can be used to compare the differences between the group means. It was found for the 226Ra and 232Th data that there was a statistically significant difference between the city centre measurements and all other group measurements. The rest of the group measurements were not significantly different from each other. When the data for 40K activity concentration measurements were evaluated, the measurements obtained from the city center were statistically different (p<0.05) from the measurements of other districts except those performed for the Yalvaç district (p>0.05). Additionally, it was also found that there was no statistically significant difference among the remaining 11 districts (p>0.05). After the determination of the activities of natural radionuclides in soil, the radiological parameters such as absorbed gamma dose rate (D), radium equivalent activity (Raeq), annual effective dose equivalent (AEDE), male lifetime cancer risk (LCRm), female lifetime cancer risk (LCRf) and external hazard index (Hex) were also calculated. The average absorbed gamma dose rate for Isparta province was determined as 25.34 nGyh-1. It was 65.76 nGyh-1 for the city center. While the average radium equivalent activity calculated for soil samples in the province was 53.94 Bqkg-1, it was determined as 142.36 Bqkg-1 for the city center. The annual effective dose equivalent average was 31.07 µSvy-1 across the province, while the mean for the central district was 80.64 µSvy-1. The average lifetime cancer risks for men and women in the Isparta province were calculated as 0.13×10-3 and 0.14×10-3, respectively. For the central district, these values were obtained as 0.35×10-3 and 0.37×10-3, respectively. The average external hazard index was found to be 0.15 for the province, and it was 0.38 for the city center. It was concluded that the average radiological parameter values for the province were lower than the world and country averages, but the averages calculated for the city center (except for the Hex and Raeq values) were higher than the national and world averages. Within the scope of this thesis, between June and August 2022, wheat samples were also collected from 65 of the sampling points where soil samples were taken. After the wheat samples were ground into flour, the activity concentration levels of 226Ra, 232Th, 40K and 137Cs in these specimens were measured. Activity concentration levels in wheat samples were investigated for the first time in Isparta and were determined as 0.45 Bqkg-1, 0.46 Bqkg-1, 57.40 Bqkg-1 and 0.08 Bqkg-1 for the 226Ra, 232Th, 40K and 137Cs radionuclides, respectively. It can be stated that these averages are consistent with the values reported in the literature for wheat samples. The transfer factor values indicate how much of the radionuclides in the soil are absorbed by wheat metabolism. For 226Ra the transfer factor values ranged from 0.01 to 0.27, for 232Th it ranged from 0.01 to 0.15, for 40K it ranged from 0.12 to 0.87, and for 137Cs it ranged from 0.01 to 0.27.