Terrestrial Gamma Radiation Dose Rate Research Articles

Isodose mapping of terrestrial gamma radiation in Sarawak-Borneo: Insights from surface-weathered soil analysis

Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h−1 and a range of 8–375 nGy h−1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h−1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h−1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h−1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h−1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h−1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.

Assessment of Outdoor Terrestrial Gamma Radiation Dose Rates of Serule Village, Botswana

Assessment of Outdoor Terrestrial Gamma Radiation Dose Rates of Serule Village, Botswana

Terrestrial gamma radiation dose (TGRD) levels in northern zone of Bauchi, Nigeria: mapping and statistical relationship between gamma dose rates and geological formations

This present study aims to obtain baseline data of environmental terrestrial radiation and to assess the corresponding health risk in the ambient environment in Bauchi north. The Terrestrial gamma radiation dose rates (TGRD) of study area were measured on-site using a portable Radiation alert milli roentgen (mR) survey meter, with a total of 280 measured points which covered all geological formations of the study area. The TGRD ranged from 60.90 nGyh-1 to 313.20 nGyh-1 with a mean value of 165.48 nGyh-1, which is about two times higher than the world average value of 59 nGyh-1 . Geological formation (Granites) was found to have the highest mean TGRD value of 194.88 nGyh-1. Likewise, Geological formation (Quartenary sedimentary) appeared to have the lowest mean TGRD value of 151.82 nGyh-1. The map for the distribution and exposure rate due to TGRD for the study area was also plotted using Golden surfer 12 software. One-way ANOVA was used to investigate the variation of the significant difference between the geological formations with TGRD, which shows the influence of geological formation on the measured TGRD values of the study area. Measured data could further be used to evaluate the public radiation exposure and in formulating safety standards and radiological guidelines.

Micro-mapping of terrestrial gamma radiation dose rate in typical urban homes in Miri City (Sarawak, Malaysia)

Micro-mapping of terrestrial gamma radiation dose (TGRD) at meter grid spacing in and around four urban homes in Miri City shows rates ranging from 70 to 150 nGy/h. Tiled surfaces (floors and walls) vary between properties and have a clear and significant influence on TGRD which is highest in kitchens, washrooms and toilets. Application of a single indoor value for annual effective dose (AED) may lead to underestimations of up to 30%. The AED is unlikely to exceed 0.8 mSv in homes of this type in Miri, which is within recommended guidelines.

In situ assessment of terrestrial gamma radiation dose and associated radiological hazards in Katsina State, Nigeria

ABSTRACT Terrestrial gamma radiation dose (TGRD) rates were measured in situ from different locations in Katsina State, Nigeria, using a portable radiation survey metre based on geological formations and soil types. The measured TGRD rates ranged from 45 to 271 nGyh–1 with an average value of 116 ± 1 nGyh–1. Geological formation (silicified sheared rock) and soil type (lithosols and ferruginous crusts and ferruginous tropical soils) appeared to have the highest mean TGRD values of 163 and 134 nGyh–1 with sandstone geological formation and alluvial and hydromorphic soils having the lowest TGRD with values of 80 and 61 nGyh–1, respectively. One way ANOVA results shows that the tested null hypothesis was rejected. Thus, indicating that there exists a strong relationship between the various geological formations, soil types with the measured TGRD values based on the alternate hypothesis. Human health hazard indices like annual effective dose equivalent (AEDE), lifetime outdoor annual equivalent dose, and relative excess lifetime outdoor cancer risk associated with the mean TGRD of the study area were also calculated and found to be 0.711, 9.955 mSv, and 5.79 × 10–4, respectively. These values were higher than the world average values but favourable compared with the safety limits recommended by ICRP.

Monitoring of terrestrial gamma radiation exposure in different geological Stress conditions of Uttarakhand Himalayan region, India

Terrestrial gamma radiation dose (TGRD) exposure on the earth’s surface establishes the linkages with the distribution of radionuclide elements in that particular environmental condition. The rate of variation of the terrestrial gamma radiation in the environment is directly associated with the regional geology and to the elemental concentration of these elements. In this study, Environmental TGRD rates (mSv/h) were measured over the three different geological conditions (Kamal valley, Tona valley and Yamuna valley) with the objective of establishing baseline data on the background radiation. An extensive survey of gamma-ray dose rate is conducted focusing the areas highly suitable for fractures and valley zones. The rocks types in the study regions are basically unconsolidated and moderately structured. The Gamma-ray dose rate at one (1) meter above the ground was measured at 46 points, using a pocket survey dosimeter which. The highest TGRD rate (0.27 mSv/h) is observed (with 35% estimation error) at the location of Rama site in the Kamal valley. Similarly, for Buthothra site of Tons valley it is found to be 0.21 mSv/h with estimation error 37% and at Rekhud site of Yamuna valley it is 0.19 mSv/h with estimation error 36%. The ranges of the gamma dose rate in other sites are also found under the recommended value with normal distribution.

Radiological assessment subjected to outdoor radon and thoron concentrations and terrestrial gamma radiation measurements in Perak Malaysia

The concentrations of radon, thoron and terrestrial gamma radiation were measured to evaluate the outdoor effective dose. The outdoor radon activity concentration ranged from 5.79 to 5110 ± 46.36 Bq m−3, with a mean of 320.03 Bq m−3 which is higher than the EPA level of 14.8 Bq m−3. The range of the thoron activity concentration outdoor was from 0.00 to 4226.7 ± 58.5 Bq m−3, with a mean of 226.1 Bq m−3 which was above the UNSCEAR recommended level of 10 Bq m−3. The terrestrial gamma radiation dose rates range was from 98.31 to 3769.71 nGy h−1 with a mean of 446.27 nGy h−1. The effective dose contribution from radon exposures in the study was estimated to be 3.2 ± 0.5 mSv y−1 is about 84% total annual effective dose received by the population in those areas. The estimated thoron and gamma dose contributions (15%, and 1% respectively) were not significant. The outdoor doses for thoron and gamma were lower than the ICRP (2007) value of 1 mSv. The total annual outdoor effective dose with an occupancy factor of 1825 h (5 h day−1) was estimated to be within the range of 0.30–551.41 ± 0.65 mSv, with a mean of 3.75 mSv which is a little higher than the world average of 2.4 mSv.

Development of statistical model for predicting terrestrial gamma radiation dose

Natural environmental radioactivity aroused mainly from primordial radionuclides such as 40K and 238U and 232Th decay series, and have been present in varying concentrations within the earth and in the tissue of every living being. Natural radioactivity can be found everywhere; in the soil, public water supplies, oil, and the atmosphere and it poses a measurable exposure to human beings. The present study developed a statistical model that can be used to predict the Terrestrial Gamma Radiation Dose rates (TGRD) based on soil types and geological formations irrespective of the environment. About 295 TGRD measurements were taken using a micro-Roentgen survey meter (model 19) manufactured by Ludlum, from different locations within the study area. Statistical Package for Social Sciences (SPSS) was utilized in establishing the relationships between TGRD with underlying geological formations and soil types as well as in the development of the model. The developed model was tested by predicting the TGRD value over different combinations of soil types and geological formations, and it was found to fit in well with more than 80% degree of accuracy which is within the acceptable limit. The developed model in this study, may help in establishing the background radioactivity levels in a terrestrial environment that can be used to evaluate any changes that may arise as a result of any release due to both natural and or human activities in a certain area.

Statistical analysis of terrestrial gamma radiation dose rates in relation to different geological formations and soil types of Katsina State, Nigeria

ABSTRACT Terrestrial gamma radiation is the major source of outdoor radiation exposure to human being. Because of the variation of underlying geological characteristics of surface soil, the terrestrial gamma radiation dose (TGRD) rates vary significantly with the soil type. This work performed in situ measurements of the TGRD rate for a range of geological formation and soils of Katsina State, Nigeria by using a portable hand-held radiation survey metre, RADOS. The TGRD rates ranged between 45 and 271 nGyh−1 with an overall mean value of 116 nGyh−1, which is two times higher than the world average value of 59 nGyh−1. Geological formation (Silicified sheared rock) was found to have the highest mean TGRD value of 163 nGyh−1. Likewise, soil type (lithosols, ferruginous crusts and ferruginous tropical soils) appeared to have the highest mean TGRD value of 134 nGyh−1. One-way ANOVA was used to investigate the variation of the significant difference between the geological formations and soil types with TGRD, which shows the influence of geological formation and soil types on the measured TGRD values of the study area. Measured data could further be used to evaluate the public radiation exposure and in formulating safety standards and radiological guidelines.

Terrestrial gamma radiation dose rate mapping and influence of building materials: case study at Curtin University campus (Miri, Sarawak, Malaysia)

Detailed mapping of indoor and outdoor terrestrial gamma radiation dose (TGRD) rate at Curtin University campus (Miri, Sarawak, Malaysia) shows rates ranging from 50 to 150 nGy/h with an average of 89.8 nGy/h. Indoor locations with artificial ground cover have on average 37% higher TGRD rates compared to outdoor sites. The spatial influence of building materials on the ambient TGRD rates is clear. The annual effective dose is 0.65 mSv which is well within guidelines indicating there is no radiation risk to campus residents. Of this, 0.15 mSv is due to building materials, of which tiles have the highest contribution.

Investigation of potential environmental radiation risks associated with artisanal gold mining in Zamfara State, Nigeria

A total number of 166 average measurements were taken using a handheld radiation meter. The mean terrestrial gamma radiation dose rate (TRD) was 32 nGy h−1 which is less than the world average value of 59 nGy h−1. Kaura Namoda has the highest TRD with a value of 38 nGy h−1, while Bakura has the lowest TRD with a value of 28 nGy h−1. The mean activity concentrations of 226Ra, 232Th and 40 K in soil samples were measured using HPGe and were found to be 18 ± 2 Bq kg−1, 22 ± 3 Bq kg−1 and 251 ± 7 Bq kg−1, respectively. Highest activities of 226Ra, 232Th and 40 K were all found to be in Zurmi local government area with respective values of 31 ± 3 Bq kg−1, 34 ± 3 Bq kg−1 and 419 ± 10 Bq kg−1. The radiological hazards indices associated with the measured activity concentrations were determined as 69 Bq kg−1, 0.2, 0.24, 32 nGyh−1 and 0.05 mSvy−1 for radium equivalent (Raeq), external hazard index (Hex), absorbed dose rate (DR) and annual effective dose (AED), respectively. It can be concluded that despite the illegal mining activities within the area, the radiation exposure level in the area is normal and will not pose any immediate radiation effect to humans and their environs.

Measurement of terrestrial gamma radiation dose rate and radioactivity levels in the southern hilly regions of Manipur, India

The terrestrial gamma radiation levels and associated dose rates were estimated at 120 different sites with 12 soil samples in the southern hilly regions of Manipur, India, consisting of Churachandpur and Chandel district, by using NaI (Tl) scintillator-based Micro-R survey meter and high-purity germanium detector. The observed annual effective dose in this study area ranges from 0.37 to 1.51 mSv/y, with a mean value of 0.85 ± 0.16 mSv/y. Whereas Churachandpur and Chandel districts showed a mean value of 0.88 ± 0.18 (ranges: 0.67 to 1.51) mSv/y and 0.83 ± 0.14 (ranges: 0.37–1.24) mSv/y, respectively. This southern region of Manipur shows slightly higher values of annual effective dose as compared with the earlier reported value of about 0.7 mSv/y for the central valley region of Manipur, and world average value of about 0.4 mSv/y, reported by United Nations Scientific Committee on the Effects of Atomic Radiation (2000). The soil analysis for226Ra,232Th, and40K of this area gives an average activity concentration of 44.3 (ranges: 23.8–78.6) Bq/kg, 169.1 (ranges: 83.6–305.1) Bq/kg, and 1489.1 (ranges: 752.5–2426.8) Bq/kg, respectively.

Natural radioactivity and associated radiation hazards in soil of Kelantan, Malaysia

ABSTRACTRadiological effects due to external and internal exposure to natural radiation associated with the natural radionuclides 226Ra, 232Th, and 40K in soil of Kelantan, Malaysia was carried out. Terrestrial gamma radiation dose rates (TGRD) measurement was carried out using a portable [NaI(TI)] micro roentgen (µR) survey meter and hyper purity germanium (HPGe) detector for the activity concentrations of 226Ra, 232Th, and 40K in soil samples. The mean TGRD was found to be 209 nGy h−1 and from soil samples analyzed, the mean activity concentrations of 226Ra, 232Th, and 40K were found to be 82 Bq kg−1, 123 Bq kg−1, and 643 Bq kg−1 respectively, which were both about 3 times higher than the Malaysian average as reported by UNSCEAR 2000. The mean radium equivalent (Raeq), absorbed dose rates (D), annual effective dose (H), annual gonadal dose equivalent (AGDE) as well as external and internal radiation hazard index (Hex), which were the indicators of radiological health hazards, were found to be 307 Bq kg−1, 139 nGy h−1, 0.22 mSv y−1, 969.422 µSv y−1, 0.653 and 1.05, respectively.

Geological influence on the terrestrial gamma radiation dose rate in Jos Plateau, Nigeria

Natural environmental terrestrial gamma radiation dose (TGRD) rate measurements have been carried out across the geological formations of Jos Plateau, Nigeria. External gamma radiation dose rates ranged between 11 and 714 nGy h-1 with a mean value of 204 nGy h-1. Relationship between TGRD levels and geological type was determined. Statistical comparative method one way analysis of variance (ANOVA) was used to compare the TGRD means for the various types. The statistical results revealed in some instances, significant differences among the mean values of TGRD rates for the different underlying geological structures. Annual effective dose and collective effective dose for the general public due to exposure to terrestrial gamma radiation were estimated at 0.25 mSv y-1 and 1.20x102 mSv y-1, respectively. Isodose map for exposure rate due to TGRD wasplotted using ArcGIS software. The results will serve as database for natural background radiation for the country.Keywords: Natural radiation; Terrestrial gamma radiation dose (TGRD); geological type; Analysis of variance (ANOVA)

Estimation of Terrestrial gamma radiation (TGR) dose rate in characteristic geological formations of Jos Plateau, Nigeria

A study was conducted to estimate the terrestrial gamma radiation (TGR) dose rates associated with the natural radionuclides 238U, 232Th and 40K in the characteristic geological formations of Jos Plateau. A total of 51 surface soils from all the geological units were collected and measured using high-resolution gamma ray spectrometry system. From the measured activity concentrations of 238U, 232Th and 40K, TGR dose rates in air outdoors 1 m above ground surface, were estimated to be in the range of 36 nGy h-1 to 456 nGy h-1, depending on the geological formation, with an overall mean value of 143 nGy h-1. The estimated mean value is by a factor of two higher than the world average value of 59 nGy h-1. Geological formation G8 (Younger granites) appear to have the highest mean TGR dose rate while G7 (sandstone, clay and shale) show the lowest mean TGR dose rate. The results of this study inferred that, TGR dose rates outdoors for Jos Plateau differs with the different geological formations and significantly contributed by 232Th. An isodose map for the distribution of TGR and exposure rate to the public due to natural sources was also plotted using ArcGIS software. The data here presented can be used to evaluate public radiation dose and to produce radiological map for the country.

Health Risk Implications of Terrestrial Gamma Radiation Dose Rate in Central Jakarta, Indonesia: Short Communications

Terrestrial gamma radiation dose (TGRD) rate measurement has been conducted around downtown region of Central Jakarta Indonesia. The real time count data was taken 1 m above the ground in eight sub district locations by using a portable gamma Surveymeter of Exploranium GR-135 Plus Model. The reading position was detemined using Garmin GPSMAP 62s. The average value of TGRD rate of (47.76 ± 18.24) nSv h-1 ranged from 6.40 nSv h-1 to 120.90 nSv-1, it is higher than Indonesia. The annual effective dose rate of 0.058 mSv. Its contributes to fatal cancer risk of about 3.22 x 10-5 per year for each individual in Central Jakarta. For the subdistrict TGRD rate value was variated, however all the result is not high enough to cause for alarm.

Terrestrial gamma radiation dose (TGRD) levels in northern zone of Jos Plateau, Nigeria: Statistical relationship between dose rates and geological formations

In- situ measurement of terrestrial gamma radiation dose rates (TGRD) was conducted in northern zone of Jos Plateau and a statistical relationship between the TGRD and the underlying geological formations was investigated. The TGRD rates in all the measurements ranged from 40 to 1265nGyh−1 with a mean value of 250nGy h−1. The maximum TGDR was recorded on geological type G8 (Younger Granites) at Bisitchi, and the lowest TGDR was recorded on G6 (Basaltic rocks) at Gabia. One way analysis of variance (ANOVA) statistical test was used to compared the data. Significantly, the results of this study inferred a strong relationship between TGRD levels with geological structures of a place. An isodose map was plotted to represent exposure rates due to TGRD. The results of this investigation could be useful for multiple public interest such as evaluating public dose for the area.

Terrestrial Gamma Radiation Dose Rate of West Sarawak

A study of terrestrial gamma radiation (TGR) dose rate was conducted in west of Sarawak, covering Kuching, Samarahan, Serian, Sri Aman, and Betong divisions to construct a baseline TGR dose rate level data of the areas. The total area covered was 20,259.2 km 2 , where in-situ measurements of TGR dose rate were taken using NaI(Tl) scintillation detector Ludlum 19 micro R meter NaI(Tl) approximately 1 meter above ground level. Twenty-nine soil samples were taken across the 5 divisions covering 26 pairings of 9 geological formations and 7 soil types. A hyperpure Germanium detector was then used to find the samples’ 238 U, 232 Th, and 40 K radionuclides concentrations producing a correction factor C f = 0.544. A total of239 measured data were corrected with Cf resulting in a mean Dm of 47 ± 1 nGy h -1 , with a range between 5 nGy h -1 - 103 nGy h -1 . A multiple regression analysis was conducted between geological means and soil types means against the corrected TGR dose rate Dm, generating D g,s = 0.847Dg+ 0.637Ds- 22.313 prediction model with a normalized Beta equation of D g,s = 0.605D g + 0.395 D s . The model has an 84.6% acceptance of Whitney- Mann test null hypothesis when tested against the corrected TGR dose rates.

Environmental radiology assessment in Lahad Datu, Sabah

Monitoring terrestial gamma radiation is crucial to prepare a baseline data for environmental radiological protection. Radiological research was carried out in Lahad Datu, Sabah to obtain the radioactivity status and terrestrial gamma radiation level in the area. We measure the terrestrial gamma radiation dose rates and analyse the radioactivity concentration of primordial radionuclides for radiological risk assessment. We identified that the annual estimation of dose effective for public is below the public dose limit, 1 mSv per year. Public and environment safety and health are remain secure. The obtained data and results can be used as reference for environmental radiology protection.

Spatial distribution of natural γ radiation exposure and its relationship to soil types

An extensive survey of natural γ radiation dose rate levels was measured throughout the Melaka State, Malaysia. The main objective of the present study is to verify the influence of different soil types γ radiation exposures in air using statistical analyses. One-way analysis of variances ANOVA and post hoc test using Fisher’s least significant difference (LSD) were used to test the probability of significance difference between the dose rates and soil types. The survey involved 541 measurement points of terrestrial gamma radiation dose rates in an area of 1650 km2 which covers five major soil groups based on six FAO/UNESCO soil orders. The spatial dose distributions and descriptive statistics of all measured γ radiation dose rates are presented. It has the mean value of 183 nGy h−1. The significance test using ANOVA shows that all dose rates for four soil groups were significantly different from each other with p sig. value <0.005 and the f-ratio lies in the rejection region, f-critical (Fα,(2, n−2)). The post hoc test using Fisher’s LSD shows that there are two main groups of dose rates with each range 152–175 nGy h−1 and 218–233 nGy h−1. These two classification groups indicated the low and high range of dose rates due to the different soil groups derived from different parent rocks. An estimation of average annual effective dose equivalent to the individual in the study area was 1.12 mSv year−1. For granitic soil region, the public is expected to receive slightly high effective dose of 2 mSv year−1. The statistical significance test shows that the soil types significantly influenced the γ radiation exposures received by the public on the ground level.