Estimation of Natural Radionuclides’ Concentration of the Plutonic Rocks in the Sakarya Zone, Turkey Using Multivariate Statistical Methods

: The study aimed to determine the natural radioactivity levels of 226 Ra, 232 Th, and 40 K by the Gamma-Ray spectrometry method, and radiological hazard parameters of the plutonic rocks in the Western and Central Sakarya Zone and to analyze the data using multivariate statistical methods. The average radiological values of samples were determined as 40 K (1295.3 Bq kg − 1 ) > 232 Th (132.1 Bq kg − 1 ) > 226 Ra (119.7 Bq kg − 1 ). According to the skewness values of the distributions of the examined radionuclides, 226 Ra (2.1) and 232 Th (0.7) seemed to be positively right-skewed while 40 K ( − 0.2) had a negatively right-skewed histogram. On the other hand, the following kurtosis values were calculated for the distributions: 226 Ra (5.8 > 3), 232 Th ( − 0.7), and 40 K ( − 0.8). Kolmogorov–Smirnov and Shapiro–Wilk tests were applied to the data to test their normality. Therefore, Spearman’s correlation coe ﬃ cient method was performed. The radionuclides of 226 Ra and 232 Th were found to have a positive correlation with radiological hazard parameters of the samples. 2 (two)-related factors identiﬁed, and the cumulative value was calculated to be 98.7% on the basis of the Scree Plot. According to the hierarchical cluster analysis, the samples that are grouped with those from Camlik region are prominent. The average radioactivity values of Camlik, Sogukpinar, Karacabey, and Sogut (except for 232 Th) regions were detected to be higher than the world averages while the value of 40 K was also found to be higher than the average values of various countries in the world.


Introduction
"Natural radioactivity" is observed all around the world, particularly in the geological environment consisting of rocks, soils, plants, fluids, and gas as well as the artificial environment consisting of man-made structures [1][2][3][4][5][6][7][8][9]. People living in environments containing natural radioactivity are exposed to different doses of radiation. People living in the natural environment receive 82% of their average annual dose (2.4 µSv) from natural radiation sources. Therefore, natural radiation sources are important The region extending from the Biga Peninsula to the Eastern Pontides is called the Sakarya Zone, which is characterized by sedimentary and igneous rocks subjected to intense deformation and metamorphism in different facies [39]. There are igneous rocks of various ages and origins in the Sakarya Zone The region extending from the Biga Peninsula to the Eastern Pontides is called the Sakarya Zone, which is characterized by sedimentary and igneous rocks subjected to intense deformation and metamorphism in different facies [39]. There are igneous rocks of various ages and origins in the Sakarya Zone

Sampling and Preparation
A total of 30 rock samples were collected from the plutonic rocks in the study area and several locations where the regional rocks dominated. An area of approximately 100 m 2 was marked at each sampling location. After removing impurities, such as stones, pebbles, and roots, 50-100 g of rock samples were taken in each corner and center of the marked area to a depth of about 50 cm. Four different samples representing the study area were taken for each sample. The sub-samples obtained were mixed and put in packages of 400-500 g. The samples were packed in polyethylene bags, systematically labeled, and the coordinates of the sample locations were recorded using Global Positioning System (GPS). The samples were homogenized using an agate mortar at the sample preparation laboratory of the Department of Geological Engineering at Akdeniz University (Turkey) and kept under normal conditions in the laboratory environment for a month to achieve secular equilibrium.
All samples were kept tightly closed with gas-tight parafilm and stored for about 30 days to form a radioactive equilibrium between 226 Ra and 222 Rn and stabilize the Compton region (7 × 3.9 days) [40].

Radioactivity Measurements Using High-Purity Germanium (HPGe) Detector and Dose Calculations
The gamma spectroscopic measurements of the plutonic rock samples were performed with AMETEK-ORTEC brand, GEM40P4 model, High Purity Germanium (HPGe) detector and Maestro32 software at the Department of Physics at Akdeniz University (Turkey). The relative efficiency of the HPGe detector was 40%. The full width half maximum (FWHM) values at 122 keV ( 57 Co) and at 1332 keV ( 60 Co) were 768 eV and 1.85 keV, respectively. The energy and efficiency calibration of the HPGe gamma spectrometer were made using the mixed source (International Atomic Energy Agency, (IAEA) 1364-43-2) of the same geometry with sample energies ranging from 47 to 1836 keV. IAEA RGU-1, RGTh-1, and RGK-1 standards were used for the quality controls and activity calculations ( Table 1). Detailed information about the measurement system is provided by [40,41]. All samples were counted for 50,000 s. Background intensities were also obtained under the same conditions before and after the measurements of the samples. In the gamma spectra of the samples, the activity concentrations of 226 Ra were determined by using 352 ( 214 Pb) and 609 keV ( 214 Bi), while the activity concentrations of 232 Th were determined by using 911 ( 228 Ac) and 583 keV ( 208 Tl) energy peaks, which were released from product radionuclides in the 238 U and 232 Th disintegration series. 40 K activity concentrations were determined by using the 1461 keV energy peak. Radionuclide activity concentrations were calculated using Equation (1): where A stands for the activity of the radionuclide in Bq kg −1 , N stands for the total net count in the energy of interest as counting time in seconds, ε stands for the efficiency of the HPGe detector in the gamma energy of interest, I γ stands for the abundance of the gamma ray, and m stands for the sample mass [40,41].

Radiation Hazards Parameters
Firstly, the samples of the radioactivity levels of the naturally occurring radionuclide materials (NORMs) collected from the study area were measured. Then, internationally adopted radiological health parameters were calculated using all of the data obtained by the gamma-ray spectrometry method (Table 2). Finally, multivariate statistical analyses were performed on all data obtained and the results were interpreted by comparing them with world averages.  [35,46,47] 11 Activity utilization index (AUI) Where A U , A Th, and A K are the activity concentrations of 238 U, 232 Th, and 40 K in (Bq kg −1 ) present in tar sand soil, respectively. f U (0.462), f Th (0.604), and f K (0.0417) are the fractional contributions to the total dose rate due to γ-radiation from the actual radionuclide of 238 U, 232 Th, and 40 K, respectively. DL and RF is duration of life (70 years) and risk factor (Sv −1 ), fatal cancer risk per Sievert. For stochastic effects, ICRP 60 uses values of 0.05 for the public.

Statistical Analysis
Multivariate statistical studies on the interpretation of radioactivity data and radiological parameters are quite important [49][50][51]. In this regard, multivariate statistical analyses are useful, and these tools are required to explain the data. In this study, multivariate statistical analyses, such as correlation analysis, factor analysis, cluster analysis, and regression analysis, were performed to interpret the data using the SPSS 23 software package.

Comparison with Other Countries
This finding of this study were compared with those of similar studies conducted in different parts of the world, and the differences between them were revealed. Table 3 gives the radiological health parameters calculated for the study area.  The recommended average value of the gamma radiation absorbed dose rate (D) ranges between 10 and 200 nGy hr −1 , and the population-weighted gamma radiation absorbed dose rate is 59 nGy hr −1 [14]. D values of the samples were observed to range between 8.7 and 691.6 nGy hr −1 and the mean value was found to be 222 nGy hr −1 . The maximum and average absorbed dose rates due to gamma radiation in the air 1 m above the ground level exceeded world limit values. Moreover, these values are well above the limit value that should be taken into account in the settlements.

Activity Concentration and Radiological Characterization
The limit value for radium equivalent activity (Ra eq ) ranges between 370 and 740 Bg kg −1 [14]. Ra eq values, which were calculated to identify the homogeneous distributions of radionuclides, were observed between 17.5 and 1503.4 Bg kg −1 with an average value of 478.3 Bg kg −1 . The maximum and average values were observed to exceed world limits.
The recommended limit value for the alpha index (Iα) is Iα < 1 µRh r −1 [14]. Iα values were calculated to be between 0.02 and 3.8 µRh r −1 with an average value of 0.7 µRh r −1 . The maximum value exceeded the recommended limit values. According to the average values, no problems were observed in terms of radon inhalation; however, there seemed a problem according to the maximum value.
While the recommended upper limit for gamma index (Iγ) is Iγ < 1 µRh r −1 , the exemption criterion of gamma dosage is Iγ < 0.3 µRh r −1 [14]. In this study, Iγ values were observed to range between 0.07 and 5.3 µRh r −1 with an average of 1.8 µRh r −1 . The maximum Iγ value exceeded the recommended upper limit. The samples with a maximum value exceeding Iγ < 0.3 µRh r −1 are not suitable to be used as a building material. The radiological effect must be at least (Iγ < 0.5) to be tolerated.
The external hazard index (H ex ) was calculated together with the internal hazard index (H in ) to evaluate the effects of the radioactivity of the surface materials on health. The recommended limit value for the external hazard index (H ex ) is (H ex < 1). In the study, Hex values were observed to be between 0.05 and 4.1 with an average of 1.3. The maximum and average values were found to exceed the limit values.
The recommended limit value for the internal alpha radiation (H in ) is H in < 1 [14]. In the study, H in values were found to range between 0.07 and 6.1, with an average of 1.7. All values were observed to exceed the limit value. According to these figures, health problems stemming from the inhalation of radon and radon products can be seen. The radiological hazard indices of the samples should be below the limit values (H ex < 1 and H in < 1) to assume their radiological effects are not significant.
The recommended world average for the annual effective dose equivalent (AEDE) is AEDE < 70 µSv yr −1 [14]. The minimum, maximum, and mean values of AEDE indoor and AEDE outdoor were calculated to be 42.7-3395.1 µSv yr −1 , 1089.7 µSv yr −1 (mean) and 10.7-848.8 µSv yr −1 , and 272.4 µSv yr −1 (mean), respectively. The samples were observed to have high AEDE indoor values. The maximum and mean values were found to exceed limit values. The regions seem to have a health problem of inhalation of radon and its products.
The recommended limit for the annual gonadal dose equivalent (AGDE) is AGDE < 300 µSv yr −1 [14]. An active cell's direct exposure to radiation may damage the reproductive organs, active bone marrow, and bone surface cells; it may even lead to cell mutation or death [14,52,53]. In this study, the AGDE values ranged between 61.6 and 4779.9 µSv yr −1 , and the average AGDE was observed to be 1559.3 µSv yr −1 . The maximum and average AGDE values were found to exceed the limit values. These findings are significant since the radiation taken by the reproductive organs (gonads) of the population exceeds the recommended annual dose equivalent.
The recommended limit value for the excess lifetime cancer risk (ELCR outdoor ) is ELCR outdoor < 2.9 × 10 −4 µSv yr −1 [14]. The ELCR outdoor values were found to range between 37.3 and 2970.8 (µSv yr −1 ) with an average of 953.5. µSv yr −1 . All values were observed to be well above the limit value. According to these results, the lifetime cancer risk of the people who live in these regions with anomalies for up to 70 years due to land use is quite high. Therefore, the contact of people living in these regions with these plutonic rocks in their living areas should be reduced.
If the recommended limit value for the activity utilization index (AUI) is AUI ≤ 1, the dose that the individual receives corresponds to 0.3 µSv yr −1 . On the other hand, if the limit value is AUI ≤ 3, the dose that the individual receives corresponds to 1 µSv yr −1 [14]. In this study, the AUI values were observed to range between 0.1 and 11.6 µSv yr −1 with an average of 3.3 µSv yr −1 . Since the maximum and average values exceeded the limit value (AUI ≤ 3), the regions were found to have excess amounts of external gamma radiation (1 µSv yr −1 ) due to the surface materials.
The regions in the study area from where the samples with the maximum and average values exceeding the international limit values were taken may pose significant radiological risks to the people living there.

Descriptive Statistics
Descriptive statistical analyses were applied to radiological indices calculated by the radiological analyses and the data obtained from them ( Table 4). The mean values of the radionuclides obtained by radiological analyses were ordered as follows: 40 K (1532.6 Bq kg −1 ) > 226 Ra (148.5 Bq kg −1 ) > 232 Th (148.1 Bq kg −1 ). It is noteworthy that the values of 226 Ra and 32 Th are close to each other, and they show a similar concentration. This indicates that these radionuclides showed similar behavior and that they are not affected by the metamorphism of the rocks. The samples were not taken from the same location. The standard deviation values of radionuclides were found to be high due to the fact that the sample rocks taken from different locations had different chemical contents and differ in terms of their minimum and maximum values. This is an expected case in terms of statistics. The kurtosis values of the distributions of the radionuclides were found to be 226 Ra (5.8 > 3), 232 Th (−0.7), and 40 K (−0.8) in the descending order. While the distribution of 226 Ra had a leptokurtic shape, the distributions of 232 Th and 40 K had platykurtic shapes (Table 4, Figure 2).
The skewness range of (−2 < skewness < 2) covers 95% of the total area, while the skewness range of (−3 < skewness < 3) covers 99% of the total area. The skewness values of the radionuclides were found to be 226 Ra (−3 < 2.1 < 3), 232 Th (−2 < 0.7 < 2), and 40 K (−2 < −0.2 < 2) in the descending order. While the distribution of 226 Ra was found to have a right-skewed and asymmetrical shape, the distributions of 232 Th and 40 K could be assumed to have a normal distribution. Figure 3 clearly indicates that the linear correlation coefficient between the effective 226 Ra content and 232 Th content was 0.9, pointing to the high strong linear dependency between both concentrations in the plutonic rocks. The skewness range of (−2 < skewness < 2) covers 95% of the total area, while the skewness range of (−3 < skewness < 3) covers 99% of the total area. The skewness values of the radionuclides were found to be 226 Ra (−3 < 2.1 < 3), 232 Th (−2 < 0.7 < 2), and 40 K (−2 < −0.2 < 2) in the descending order. While the distribution of 226 Ra was found to have a right-skewed and asymmetrical shape, the distributions of 232 Th and 40 K could be assumed to have a normal distribution. Figure 3 clearly indicates that the linear correlation coefficient between the effective 226 Ra content and 232 Th content was 0.9, pointing to the high strong linear dependency between both concentrations in the plutonic rocks.  The skewness range of (−2 < skewness < 2) covers 95% of the total area, while the skewness range of (−3 < skewness < 3) covers 99% of the total area. The skewness values of the radionuclides were found to be 226 Ra (−3 < 2.1 < 3), 232 Th (−2 < 0.7 < 2), and 40 K (−2 < −0.2 < 2) in the descending order. While the distribution of 226 Ra was found to have a right-skewed and asymmetrical shape, the distributions of 232 Th and 40 K could be assumed to have a normal distribution. Figure 3 clearly indicates that the linear correlation coefficient between the effective 226 Ra content and 232 Th content was 0.9, pointing to the high strong linear dependency between both concentrations in the plutonic rocks.

Correlation Analysis
A correlation analysis was performed to determine the relationship and similarity between all the data obtained. The normality of the data was tested before performing multivariate statistical analyses. The Kolmogorov-Smirnov and Shapiro-Wilk tests were used to test the normality of the distributions ( Table 5). The significance values of all the data were calculated to be less than 0.05 (sig. < 0.05). Therefore, Spearman's correlation coefficient was used in the correlation analysis. In general, the radionuclides have a positive correlation with the radiological parameters, which were obtained from the analysis of radionuclides (Table 6). In particular, while the radionuclides of 226 Ra and 232 Th have a positive correlation with the radiological parameters, 40 K has a lower positive correlation with these parameters. 40 K was observed to have a lower correlation with all other variables compared to the other radionuclides. Therefore, 226 Ra and 232 Th were found to have a more significant contribution to the radioactivity in the plutonic rocks. As a result, the variables that showed a positive correlation with the radioactivity parameters were interpreted to behave similarly and were of the same origin.

Factor Analysis
Factor analysis was applied to obtain significantly explained variables from the results of the analyses and calculations. The automatic factor selection tool of SPSS found one (1) factor with an eigenvalue greater than 1. However, the rotation sums of squared loadings method was applied to reveal the variance of the data and particularly 40 K, even it was very low; thus, the number of factors was selected as two (2) manually. In this context, two factors were extracted, and the cumulative value of variance explained was determined to be 98.7%. The results showed that the significant variance of the data was calculated very perfectly (Table 7). Principal component analysis (PCA) was performed after factor analysis. According to the results of the rotated component matrix data, two components were determined ( Table 8). The first factor was determined to consist of 226 Ra, 232 Th, Ra eq , D, Iα, Iγ, Hex, H in , AEDE indoor , AEDE outdoor , AGDE, ELCR, and AUI, and their total variance was found to be 95.1%. The second factor was determined to consist of 40 K with a total variance value of 3.5%. The radionuclide of 40 K, which constitutes a separate component, is completely independent of the variables representing the other component. With its percentage of 3.5% in the grand total, 40 K has a high effect on the total variance. It has an important place in the statistical evaluation of the data. This finding indicates that 40 K has a different effect than 226 Ra and 232 Th. It is considered that the radionuclides of 226 Ra and 232 Th are influenced by granitic rocks, as well as 40 K being affected by rock alterations, and clayey rocks have more effect on this radionuclide. After analyzing the Scree Plot of the data used in the factor analysis, it can be seen that the data is flattened after the second factor; therefore, extraction of two factors from these data seems to be appropriate (Figure 4). According to the principal component analysis, 226 Ra and 232 Th radionuclides were found to have a very high effect on the radiological parameters; this finding seemed to be compatible with the correlation analysis. 40 K showed a different behavior compared to the other radionuclides and indices and seemed to be distant from them ( Figure 5).

Cluster Analysis (CA)
The Wards method was used in the hierarchical cluster analysis and the Q-mode cluster showed an arbitrary similarity level of 50%. Two (2) groups were determined in the dendrogram of a total of 30 samples (Figure 6  According to the principal component analysis, 226 Ra and 232 Th radionuclides were found to have a very high effect on the radiological parameters; this finding seemed to be compatible with the correlation analysis. 40 K showed a different behavior compared to the other radionuclides and indices and seemed to be distant from them ( Figure 5). According to the principal component analysis, 226 Ra and 232 Th radionuclides were found to have a very high effect on the radiological parameters; this finding seemed to be compatible with the correlation analysis. 40 K showed a different behavior compared to the other radionuclides and indices and seemed to be distant from them ( Figure 5).

Cluster Analysis (CA)
The Wards method was used in the hierarchical cluster analysis and the Q-mode cluster showed an arbitrary similarity level of 50%. Two (2) groups were determined in the dendrogram of a total of 30 samples (Figure 6

Cluster Analysis (CA)
The Wards method was used in the hierarchical cluster analysis and the Q-mode cluster showed an arbitrary similarity level of 50%. Two (2) groups were determined in the dendrogram of a total of 30 samples (Figure 6

Comparison with Other Countries
Before comparing the average values of plutonic rock samples collected from the study area with the world averages, muscovite schist sample (N6-KR-3) as a metamorphic rock, aplite sample (N13-E-3) as a dike, and pegmatite rock samples (N14-E-14, N18-ST-59, N23-KP-2) were excluded from the dataset in the calculation of the average values since they increased the grand mean significantly. The values of 226 Ra (148.53), 232 Th (148.11), and 40 K (1532.59) seemed to have an abnormally negative impact on the grand mean of the region. In particular, the aplite sample No. N13-E-3 collected from the Camlik region had the highest 40 K value while the pegmatite rock sample No. N14-E-14 had the highest 226 Ra value. All the data about 40 K were grouped into four equal classes (10.5-624; 624-1694.9; 1695-2582.4; 2582.4-3569.1), and star figures were created from these new data; then, they were marked on the site location map (Figure 1).
The mean values of granite, metagranite, and chlorite schist samples were taken into consideration to evaluate the situation using similar samples from various countries in the world ( Table 9). The average 226 Ra (119.7), 232 Th (132.1), and 40 K (1295.3) values were compared with the world averages of the granite samples in terms of the average natural radioactivity behavior of these rocks. Additionally, the samples were compared with the average values of the natural granite samples from different countries and different regions of Turkey, including the commercial ones and the imported ones.

Comparison with Other Countries
Before comparing the average values of plutonic rock samples collected from the study area with the world averages, muscovite schist sample (N6-KR-3) as a metamorphic rock, aplite sample (N13-E-3) as a dike, and pegmatite rock samples (N14-E-14, N18-ST-59, N23-KP-2) were excluded from the dataset in the calculation of the average values since they increased the grand mean significantly. The values of 226 Ra (148.53), 232 Th (148.11), and 40 K (1532.59) seemed to have an abnormally negative impact on the grand mean of the region. In particular, the aplite sample No. N13-E-3 collected from the Camlik region had the highest 40 K value while the pegmatite rock sample No. N14-E-14 had the highest 226 Ra value. All the data about 40 K were grouped into four equal classes (10.5-624; 624-1694.9; 1695-2582.4; 2582.4-3569.1), and star figures were created from these new data; then, they were marked on the site location map (Figure 1).
The mean values of granite, metagranite, and chlorite schist samples were taken into consideration to evaluate the situation using similar samples from various countries in the world ( Table 9). The average 226 Ra (119.7), 232 Th (132.1), and 40 K (1295.3) values were compared with the world averages of the granite samples in terms of the average natural radioactivity behavior of these rocks. Additionally, the samples were compared with the average values of the natural granite samples from different countries and different regions of Turkey, including the commercial ones and the imported ones. Considering the average values of granite, metagranite, and chlorite schist samples, 226 Ra (119.7), 232 Th (132.1), and 40 K (1295.3) values were found to exceed the world averages ( Table 9). The 226 Ra value of the samples seemed to be higher than all other samples except for those from the South Eastern Desert (Egypt), Ezine (Turkey), and commercial ones (China). The 232 Th value was determined to be higher than all other samples, except for commercial ones (China). The 40 K value showed higher values than all other samples, except for those from Al Madinah (Saudi Arabia) and Juban (Yemen).
Likewise, the average radioactivity values of the plutonic rock samples from Camlik, Sogukpinar, Karacabey, and Sogut (except for 232 Th) were found to be higher than the world averages. Particularly, the 40 K values in these regions were higher than those of samples from various countries in the world. The average radioactivity values of the plutonic rock samples from Ericek and Kapanca were found to be lower than the world averages and those of samples from other regions (Figure 7).

Juban (Yemen).
Likewise, the average radioactivity values of the plutonic rock samples from Camlik, Sogukpinar, Karacabey, and Sogut (except for 232 Th) were found to be higher than the world averages. Particularly, the 40 K values in these regions were higher than those of samples from various countries in the world. The average radioactivity values of the plutonic rock samples from Ericek and Kapanca were found to be lower than the world averages and those of samples from other regions (Figure 7).

Conclusions
The radiological levels of the plutonic rock samples from various regions in the Sakarya Zone were measured and their radioactivity parameters were calculated; then, all data were interpreted using multivariate statistical methods.
Considering the average radioactivity concentrations of granite and metagranite, which are plutonic rocks, and chlorite schist, which is a metamorphic rock, the abundance order was determined to be 40 K (1295.3 Bq kg −1 ) > 232 Th (132.1 Bq kg −1 ) > 226 Ra (119.7 Bq kg −1 ). Therefore, the plutonic rocks should be identified in similar studies, and dikes should not be taken into consideration in the calculation of the grand mean.
The average values of the absorbed dose rate (D), radium equivalent activity (Ra eq ), external hazard index (H ex ), internal hazard index (H in ), the annual effective dose equivalent values of AEDE indoor and AEDE outdoor , the annual gonadal dose equivalent (AGDE), excess lifetime cancer risk (ELCR outdoor ), and activity utilization index (AUI) were found to be 222, 478.3, 1.3, 1.7, 1089.7, 272.4, 1559.3, 953.5, and 3.3, respectively. All average values were found to exceed world limit values. The averages of the alpha index (Iα) and gamma index (Iγ) values were found to be 0.7427 and 1.7463, respectively. Therefore, the radiological effect was determined to exceed the value that can be tolerated (Iγ < 0.5). The results of the AUI calculations revealed that there was external gamma radiation from the surface materials.
According to the descriptive statistics applied as part of the multivariate statistical analyses, the skewness values of the radionuclides were found to be 226 Ra (−3 < 2.1 < 3), 232 Th (−2 < 0.7 < 2), and 40 K (−2 < −0.2 < 2). The distribution of 226 Ra was found to have a positively right-skewed and asymmetrical shape while the distribution of 232 Th had a positively right-skewed symmetrical shape, and 40 K had a negatively right-skewed and symmetrical shape. The kurtosis values of the distributions of the radionuclides were found to be 226 Ra (5.8 > 3), 232 Th (−0.7), and 40 K (−0.8) in the descending order. The 226 Ra radionuclide had a sharply peaked and the highest distribution.
Kolmogorov-Smirnov and Shapiro-Wilk normality tests were performed, and the significance values were found to be less than 0.05 (sig. < 0.05). Therefore, it was decided that the data did not have a normal distribution, and Spearman's correlation coefficient method was performed. A positive correlation was found between 226 Ra, 232 Th, and the radiological parameters. It was interpreted that they had a higher radioactivity effect. However, 40 K did not show a similar correlation level. The findings also reveal that the radionuclides of 226 Ra and 232 Th are geologically affected by granitic rocks. On the other hand, 40 K was affected by clayey rocks formed by the alteration of granitic rocks.
Factor analysis resulted in two factors with a cumulative value of 98.7%. While one of the factors represents 40 K (3.5%), the other factor represents all remaining variables (95.2%). The diagram clearly shows that 40 K is positioned in a different location from other variables. Moreover, the Scree Plot of the variables is flattened after the second component.
Two (2)  The radiological values of the samples from the Sakarya Zone are higher than the world average. The 226 Ra value was found to be lower than the values of the samples from the South Eastern Desert (Egypt), Ezine (Turkey), and commercial ones (China). The 232 Th value was found to be lower than that of the commercial sample (China), and the 40 K value was found to be lower than the values of the samples from Al Madinah (Saudi Arabia) and Juban (Yemen). However, the values were found to be higher than other samples from various regions of the world.
The average radioactivity values of Camlik, Sogukpinar, Karacabey, and Sogut (except for 232 Th) were observed to be higher than the world averages. The average 40 K value was higher than the world average, as well as the values of samples from various countries in the world.
The samples exceeding the limit values are not suitable for use as a building material. Inhalation of radon and its products may lead to health problems. The AGDE calculations revealed a significant finding that the radiation received by the reproductive organs (gonads) of the population exceeds the annual gonadal dose equivalent. According to the ELCR outdoor calculations, the lifetime cancer risk for up to 70 years due to land use is high. Therefore, it will be appropriate to carry out a follow-up on the rocks used as products quickly and effectively. The scope of the production of these rocks, their marketing, and use as a building material should be limited.