In situ measurement of terrestrial gamma dose rates in eastern region of Peninsular Malaysia and its relation to geological formation and soil types (original) (raw)
Related papers
Terrestrial gamma radiation dose rates (TGRD) from surface soil in Negeri Sembilan, Malaysia
Radiation Physics and Chemistry, 2014
Isodose map of terrestrial gamma radiation dose rate measured from soil surface at Negeri Sembilan was plotted and is in the range of 71-1000 nGy/h. Study shows a close relationship between geological formations, soil type distribution and terrestrial gamma radiation dose rate measured. The annual effective dose to the population of Negeri Sembilan was calculated to be 0.96 mSv per year.
Journal of Environmental Radioactivity, 2015
This study aims to predict and estimate unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis methods to derive a model from the actual measurement based on geological formation and soil type. The measurements of TGDR were conducted in the state of Johor with a total of 3873 measured points which covered all geological formations, soil types and districts. The measurements were taken 1 m above the soil surface using NaI [Ti] detector. The measured gamma dose rates ranged from 9 nGy h À1 to 1237 nGy h À1 with a mean value of 151 nGy h À1 . The data have been normalized to fit a normal distribution. Tests of significance were conducted among all geological formations and soil types, using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types present in Johor State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (D G,S ) with the gamma dose rate based on geological formation (D G ) or soil type (D s ). A very good correlation was found between D G,S and D G or D G,S and D s . A total of 118 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The contribution of the gamma dose rate from geological formation and soil type were found to be 0.594 and 0.399, respectively. The null hypotheses were accepted for 83% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information.
Geological influence on terrestrial gamma radiation dose rate in the Malaysian State of Johore
Applied Radiation and Isotopes, 2001
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 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 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 exp mSv y-1 and 1.20x10 2 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.
Terrestrial Gamma Radiation Dose Rate of West Sarawak
EPJ Web of Conferences, 2017
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 Cf = 0.544. A total of 239 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 DG,S = 0.847DG + 0.637DS-22.313 prediction model with a normalized Beta equation of DG,S = 0.605DG + 0.395DS. The model has an 84.6% acceptance of Whitney-Mann test null hypothesis when tested against the corrected TGR dose rates.
Journal of Ovonic Research, 2013
The radiation survey of the ambient environment was conducted using two gamma detectors and the measurement results were used in the computation of the mean external radiation dose rate, mean weighted dose rate, annual effective dose and the collective effective dose, which are 69 nGy h-1, 0.447 mSv y-1, 237 μSv and 0.126 × 102 man Sv y-1, respectively. A hyper purity germanium (HPGe) detector was used to determine the activity concentrations of 232Th, 226Ra and 40K in soil samples. The results of the gamma spectrometry of the soil samples show a range from 2 ± 1 to 113 ± 9 Bq kg-1 for 232Th, 3 ± 1 to 68 ± 6 Bq kg-1 for 226Ra, and 26 ± 3 to 683 ± 29 Bq kg-1 for 40K. Radium equivalent activity (Raeq) and external hazard index (Hex) were 136 Bq kg-1 and 0.366 respectively; which were with recommended level for the population. The Mean lifetime dose and life time cancer risk for each person living in the area are 5.91 mSv, 3.44×10-4 Sv year, respectively. The results was compared with values giving in UNSCEAR 2000.
Caliphate Journal of Science and Technology, 2024
Background radiation information is a viable tool for mitigating negative influence of the Terrestrial Gamma Radiation Dose rate (TGRD) on humans and their livelihood, Terrestrial gamma radiation plays significant role in background radiation which largely depends on the type of soil and fundamental geological pattern in a location. Several In situ evaluation of gamma radiation dose of the varied geological formations were performed in the area. Handheld Geiger Muller (GM) radiation survey meter (RADOS RDS-31) was used in evaluating the terrestrial gamma radiation dose while one way (ANOVA) variance analysis was employed to determine and compare the TGRD at different geological and soil formations. The external radiation dose which ranges from 15 -270 nGy/h having an overall mean value of 91.95635 nGy/h throughout the geological formations was assessed where the mean value exceeded the global limit of 59 nGyh-1 by 200%, furthermore, external gamma radiation dose rates ranging from 40 to 270 nGy/h with overall mean value of 120.0893 nGy/h. TGRD across the existing soil types was also evaluated. It was found out that the Dange formation has highest mean TGRD value of 161.1111 nGyh -1 . The assessment reveals significant influence of geological formation and soil type formation on the evaluated TGRD rates of Dange Formation.
An extensive survey was carried out for gamma dose rates (GDRs) in the Mersing district, Johor, Malaysia. The average value of GDR measured in the district was found to be 140 nGy h 21 , in the range of 40-355 nGy h 21. The mean weighted dose rate to the population, annual effective dose equivalent, collective effective dose equivalent, lifetime cancer risk were 0.836 mSv y 21 , 0.171 mSv, 1.18310 1 man Sv y 21 and 6.983 10 24 Sv y, respectively. An isodose map was produced for the district. One way analysis of variance was used to test for differences due to different geological formations present in the Mersing District.
Journal of Environmental Radioactivity, 2014
A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h À1 to 500 nGy h À1. The mean terrestrial gamma dose rate in air above the ground was 182 AE 81 nGy h À1. This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h À1 (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.
Statistical Prediction of Environmental Gamma Radiation Doses, in Perak, Malaysia
Sains Malaysiana, 2010
The concentrations of Naturally Occurring Radioactive Material (NORM) and their corresponding terrestrial gamma radiation have been shown to be associated with certain lithology and soil types. A possible relationships among gamma radiation levels, and the lithology and soil types make it possible to predict ionizing radiation level of an area that cannot be directly measured. A study was carried out to statistically predict and validate environmental gamma radiation dose rates based on actual field measurements using a sodium iodide detector. Results obtained showed that the predicted dose rate (D p) may be determined using a multiple correlation regression equation, D p = 0.35D L + 0.82 D s-0.02, that integrates dose rates contributed by different lithological structures (D L) and soil types (D s). Statistical analysis on 32 different lithology and soil type combinations showed that more than 50% of the predicted data were not significantly different from the data measured in the field. A predicted isodose map was subsequently plotted base on 4 dose rate classes ranging from 0.1-0.3 µSv h-1 .