Investigation of natural gamma radiation dose rate (GDR) levels and its relationship with soil type and underlying geological formations in Jordan

Abstract

Measurement of gamma radiation dose rates based on soil types and geological formations was carried out as a pioneer study in Jordan extensively. 823 measurements were taken at 1 m above the ground using two survey meters (Inspector Alert manufactured by S.E. International and Radiagem, 2000 Geiger Muller Counter) and the coordinates of each measurement point was recorded using a geographical positioning system (GPS). The measured GDR was found to range from 35 nGy h−1 to 470 nGy h−1 with a mean value of 90 nGy h−1 which is one and half times higher than the world's average value of 59 nGy h−1. Unbalanced one-way ANOVA test was used to investigate the variations of GDRs among all geological formations and soil types. The results indicated that there exists a strong significant difference as a result of varying soil types and geological formations. The highest mean value of 137 nGy h−1 was recorded for Acid intrusive granite rocks of Precambrian geological formation, while the lowest mean value of 65 nGy h−1 was found against Jurassic geological formation, composed of soil originated from clay and unconsolidated sedimentary rock. The results were used in production of digital map (using ArcGIS 10.2) for isodose to characterize exposure rates caused by GDR of the study area. This study will also help in establishing a GDR baseline data for future references in Jordan.