Statistical relationship between activity concentrations of radionuclides 226Ra, 232Th, 40K, and 137Cs and geological formations in surface soil of Jordan

An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides Ra-226, Th-232, K-40, and Cs-137 in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for Ra-226, Th-232, K-40, and Cs-137 has mean values of 42 +/- 3, 23 +/- 3, 309 +/- 21, and 3.7 +/- 0.9 Bq kg(-1), respectively. The highest mean activity concentration for Ra-226 was found to be 138 +/- 4 Bq kg(-1) in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35 +/- 3 Bq kg(-1) for Th-232, and 14.2 +/- 1.9 Bq kg(-1) for Cs-137, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of Th-232, K-40, and Cs-137 based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to Ra-226 activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg(-1), and 0.266, respectively.