Estimation of natural radioactivity and assessment of radiation hazard indices in soil samples of Uttara Kannada district, Karnataka, India

Assessment of natural radioactivity levels and hazard indicators in Tarakeshwor Municipality, Nepal through in-situ technique and multivariate analysis

The evaluation of primordial radionuclide concentrations in rapidly urbanized and concrete-laden areas through the importation of construction materials from various regions of Nepal is both important and essential. This study utilized a portable gamma-ray spectrometer (PGIS 2) to analyze the distribution of three natural radionuclides: uranium (238U), thorium (232Th), and potassium (40K) in Tarakeshwor Municipality, Kathmandu, Nepal. The measured dose rates ranged from 70.22 nSv hr-1 to 163.66 nSv hr-1, with an average of 124.65±20.29 nSv hr-1, surpassing the global average of 59 nSv hr-1. The activity concentrations of 40K, 238U, and 232Th exceeded global averages, indicating relatively higher natural radioactivity concentrations in the region. Specifically, the average values for 40K, 238U, and 232Th were 935.26±172.30 Bq kg-1, 80.47±15.53 Bq kg-1, and 80.44±18.58 Bq kg-1, respectively. The calculated radium equivalent (Ra eq ) ranged from 132.26 to 351.22 Bq kg-1, and the annual gonadal equivalent dose (A G E D ) varied from 372.61 to 1028.81 μSv yr-1. The annual effective dose rates for indoor and outdoor environments were 0.54±0.09 mSv yr-1 and 0.15±0.03 mSv yr-1, respectively, both exceeding the global average. The representative level index (RLI) within the study area averaged 1.96±0.32, indicating an elevated radiation risk. The excess lifetime cancer risk (E L C R ) values for outdoor and indoor environments were 0.52× 10 - 3 ±0.09 × 10 - 3 and 1.87 × 10 - 3 ±0.31× 10 - 3 , respectively, surpassing the world average. Additionally, external hazard indices (H ex ) ranged from 0.36 to 0.59, while internal hazard indices (H in ) ranged from 0.38 to 1.20, both indicating values higher than UNSCEAR recommendations. These findings underscore the necessity for further experimental analysis employing ex-situ equipment. The data generated in this study can provide a valuable baseline for future assessments and interventions in radiation risk management guidelines within the country.

Investigation of natural and artificial radioactivity levels in travertines of the Cappadocia region in Turkey

This study determined natural and artificial radionuclide concentrations to evaluate natural radioactivity and health risk levels of nine travertines in the Yaprakhisar and Balkayası regions in Turkey. The samples coded B1-M, B2, B5, B7, B8, and B10 represent waste derived from the Yaprakhisar travertines, as well as samples T5-M, T12, and Z1 travertines derived from Balkayası. The levels of natural and artificial radionuclide concentrations (232Th, 40K, and 137Cs) were measured using a high-purity germanium (HpGe) detector system. The travertine activity ranged from 2.09 to 12.07 Bq kg-1 for 232Th, 4.21 to 13.41 Bq kg-1 for 40K, and 0.42-3.26 Bq kg-1 for 137Cs. The results showed that the activity concentration values for 232Th, 40K, and 137Cs were coherent with the travertine analysis results in the UNSCEAR, 2000; 2008 publications. The values obtained were lower than the average values in the UNSEAR reports. The radiological hazard parameters calculated in this study were absorbed gamma dose rate (D), radium equivalent activity (Raeq), annual gonadal dose equivalent (AGDE), exposure dose (ER), total annual effective dose (AEDEtotal), excess lifetime cancer risk (ELCRtotal), gamma representative level (GRL), internal hazard index (Hin) and external hazard index (Hex).

Assessing radioactive contaminants in Kathmandu soils: measurement and risk analysis

Soil samples from vegetable farmland in densely populated wards of Nepal were analyzed for natural radionuclide levels, employing a NaI(Tl) 3" [Formula: see text] 3" gamma detector. The study aimed to evaluate the causes of radiation risk, attributing it to soil contamination resulting from the rapid urbanization and concretization that followed the earthquake in 2015. The activity concentration of radium-226, thorium-232, and potassium-40 and the ranges observed are 2.080±0.084-33.675±1.356 Bq kg[Formula: see text], 17.222±0.198-119.949±1.379 Bq kg[Formula: see text], and 11.203 ± 0.325-748.828±21.716 Bq kg[Formula: see text], respectively. The average values obtained for hazard indices are as follows: radium equivalent activity (82.779 Bq kg[Formula: see text]), absorbed dose rate (36.394 nGy h[Formula: see text]), annual effective dose equivalent (0.045 mSv yearr[Formula: see text]), gamma index (0.291), external hazard index (0.224), internal hazard index (0.253), excess lifetime cancer risk (0.159), annual gonadal dose equivalent (243.278 mSv year[Formula: see text]), alpha index (0.054), and activity utilization index (0.716). However, in most places, thorium-232 concentration is greater than those of the world average and recommended values. In specific locations such as Ward 4 in Baluwatar, the soil was found to have concentrations of Ra[Formula: see text] and K[Formula: see text] exceeding recommended limits. Despite this localized concern, the overall analysis of hazard indices across the studied areas revealed that most values were within permissible limits. This suggests that, on a broader scale, radiation exposure may not be a significant concern in the investigated regions. Nonetheless, the study recommends regular monitoring in additional locations to ensure a comprehensive and ongoing assessment of radiation levels.

Estimation of radioactivity in soil and drinking water samples from Northern Gulbarga District of Karnataka

The gamma activity of the radionuclides238U, 232Th and 40K were measured in surface soil samples collected from 40 villages of Aland, Afzalpur, Ganaghapur and Kamalapur talukas of Northern Gulbarga district, Karnataka. The gamma activity of natural radionuclides were measured using 4" × 4" NaI (Tl) scintillation detector, the spectrum was analysed using a PC based 1 k MCA (winTMCA 32 scinti SPEC) and the 222Rn activity concentrations in drinking water were determined by the Emanometry method. The activity of 238U, 232Th and 40K was found to be in the range from 14.3 ± 0.3 to 64.5 ± 6.1, 15.4 ± 0.2 to 95.0 ± 4.1 and 21 ± 06 to 323 ± 09 Bq kg-1, respectively. Outdoor AED from 0.023 to 0.07 mSv y-1 and all the radiological hazards indices were well within the safe limit. The 222Rn activity in ground water is found to vary from 1.11 to 66.6 Bq l-1. The total annual effective doses due to 222Rn inhalation and ingestion range from 3.02 to 181.81 μSv y-1, respectively, with an average value of 77.18 μSv y-1.

Assessment of natural radioactivity levels and potential radiological risks of commonly used building materials in Uttara Kannada District, Karnataka, India

The main goal of this study is to evaluate the natural radioactivity and potential radiological risks of frequently used building materials in Uttara Kannada district. Using an High purity Germanium Detector (HPGe) detector-based gamma-ray spectrometer, the activity concentration of 226Ra, 232Th and 40K was determined. The activity concentration of 226Ra, 232Th and 40K in the construction materials vary from 13.78 ± 0.90 to 151.9 ± 1.85, 14.21 ± 0.80 to 207.72 ± 2.9 and 55.26 ± 1.20 to 1298.24 ± 25 Bq kg-1 with an average value of 40.57 ± 1.37,60.13 ± 1.70 and 425.38 ± 4.75 Bq kg-1 having a geometric mean of 33.07, 46.49 and 290.20 Bq kg-1, respectively. The mean annual effective dose equivalent was found to be 0.68 mSv y-1 and is less than the International Commission on Radiological Protection proposed acceptable limit of 1 mSv y-1. The estimated radiological hazard parameters show that these building materials are safe to use in the construction of homes and do not offer a substantial source of radiation hazard.

A review on radionuclide pollution in global soils with environmental and health hazards evaluation

Human populations are being exposed to a wide spectrum of radiation from soils as a result of the availability of radiation sources. Assessing the ecological and health effects of radionuclides in soils is crucial to support the optimal soil management practices but large-scale studies are limited. This study compiled data on radionuclides (226Ra, 232Th, 40K, 238U, and 137Cs) in soils located across the world (44 countries and 159 places) between 2008 and 2022 and applied radiological hazards indices and several multivariate statistical approaches. The average activity concentration (Bq/kg) of 226Ra, 232Th, 40K, 238U, and 137Cs were 408.56, 144.80, 508.78, 532.78, and 83.12, respectively, whereas 226Ra, 232Th, 40K, and 238U exceeded the standard limits. The principal component analysis explained more than 91% of variation in soils. Based on the geoaccumulation index, 40K posed moderately to heavy contamination whereas 238U and 226Ra posed moderate contamination in soils. Moreover, the mean values of radiological hazards evaluation such as radium equivalent activity (487.17 Bq/kg), external radiation hazard indices (1.32), internal hazard indices (2.15), absorbed dose rate (247.86 nGyh-1), annual effective dose rate (1.82 mSvy-1), activity utilization index (4.54) and excess lifetime cancer risk (63.84 × 10-4) were higher than recommended limit suggesting significant radiological risks in study region soils. The findings indicated that the study area soils were contaminated by radionuclides and unsafe for hazards in terms of the health risks linked with studied radioactive contents. The study is valuable for mapping radioactivity across the globe to determine the level of radioactivity hazards.