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

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

Assessment of health risk associated with natural gamma dose rate levels and isodose mapping of Jordan

As a pioneering study in Jordan, an extensive measurement for external gamma dose rate (GDR) was conducted. A portable gamma radiation detector was used to perform these measurements at 1 m above the soil surface. A geographical positioning system Garmin was used to record a total of 823 measured points. The GDRs’ measurement ranged from 35 to 470 nGy h −1 giving a mean value of 90 nGy h −1 , which was found to be one and half times higher than the world average of 59 nGy h −1 . The lowest mean GDR 72 nGy h −1 was found in the Albalqa governate, while the highest mean GDR 131 nGy h −1 was found to be for the Alkarak governate. The mean annual effective dose was found to be 0.551 mSv, which is higher than the world average value of 0.48 mSv. This is a pivotal study evaluating the risks associated with GDR levels in Jordan that were the relative excess lifetime cancer risk, the mean collective effective dose, the mean weighted GDR and the mean lifetime dose that are 2.24 × 10 −3 , 5538manSv y −1 , 0.531 mSv and 39 mSv, respectively. The cosmic rays mean GDR was determined to be 20 nGy h −1 . This study focuses on constructing GDRs’ baseline data in Jordan, which will be used to determine the possible change in the natural radiation due to other human activities in the future. ArcGIS software was employed to generate an isodose map to characterise exposure rates caused by GDR in Jordan

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 226 Ra, 232 Th, 40 K, and 137 Cs 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 226 Ra, 232 Th, 40 K, and 137 Cs 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 226 Ra 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 232 Th, and 14.2 ± 1.9 Bq kg –1 for 137 Cs, 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 232 Th, 40 K, and 137 Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to 226 Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg –1 , and 0.266, respectively

Activity concentrations of 226Ra, 228Ra, 222Rn and their health impact in the groundwater of Jordan

The activity concentrations of 226Ra, 228Ra and 222Rn were measured in 87 groundwater samples to estimate the activity concentrations of these radionuclides and health impact due to intake of these radionuclides in groundwater of Jordan. The mean activity concentrations of 226Ra, 228Ra and 222Rn in groundwater were found to be 0.293 ± 0.005 Bq L−1, 0.508 ± 0.009 Bq L−1 and 58.829 ± 8.824 Bq L−1, respectively. They give a mean annual effective dose of 0.481 mSv with mean lifetime risk of 24.599 × 10−4, exceeding the admissible limit of 10−4. Most of the received annual effective dose (59.15% of the total) is attributed to 228Ra

238U and 232th isotopes in groundwater of Jordan: geological influence, water chemistry, and health impact

An extensive pioneer study was conducted to determine the activity concentration of 238U and 232Th in 94 groundwater samples to examine the influence of geological formations on the activity concentrations of 238U and 232Th and to investigate a relationship with the major chemical elements in groundwater. The study also aims to estimate the annual effective dose and health impact due to the intake of these radionuclides in the groundwater of Jordan. The mean activity concentrations of 238U and 232Th in groundwater were found to be 33 ± 5 mBq L−1 and 0.017 ± 0.002 mBq L−1, respectively. The highest mean of 238U and 232Th activity concentrations were found for lower Cretaceous geological formation, while Tertiary and Quaternary geological formations have the lowest mean 238U and 232Th activity concentration, respectively. The output of (ANOVA) and post hoc tests revealed the existence of significant influence of geological formations on 238U activity concentrations, while insignificant influence on 232Th activity concentrations was found in the groundwater of Jordan. The groundwater of Jordan was dominated by HCO3 −1, Cl−1, Ca+2, and Na+1. The mean annual effective dose due to the ingestion of radionuclides 238U and 232Th in groundwater were found 1.143 μSv lower than recommended by WHO. The ingestion dose deduced is dominated by 238U of 99% where the average contribution from 232Th amounted to 1%. The results of the study will serve as a baseline data of 238U and 232Th activity concentrations in groundwater based on geological formations of Jordan

Radiological dose and health impact to Jordanian populace due to radioactivity in staple food crops from four representative soils in Jordan

In the current study, the activity concentrations of 40K, 226Ra,232Th, and 137Cs were measured in 39 wheat crops samples and their associated soils taken from four representative soils in Jordan to estimate the annual effective dose and lifetime risk assessment due to intake of these radionuclides in wheat crops. The mean annual effective dose and the excess lifetime risk due to 40K and 226Ra intake in wheat grains was 0.4 mSv and 14.64 × 10−4 exceeding the global average of 0.178 mSv and 10−4, respectively. 226Ra had the most significant contribution (72% of the total), followed by 40K (28%)