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The Kanyakumari coast is known to be a high background natural radiation area due to the placer deposits of heavy minerals such as ilmenite, monazite, and rutile. The Kanyakumari river sediments that could be the source of the elevated amounts of natural radionuclides in the coastal sands have been studied in this paper. The activity concentrations of primordial radionuclides 226 Ra, 232 Th, and 40 K were determined using high-purity germanium (HPGe) gamma-ray spectrometry. The mean activity concentrations of 226 Ra, 232 Th, and 40 K were found to be 75 Bq kg -1 , 565 Bq kg -1 , and 360 Bq kg -1 , respectively. The mean absorbed dose rate was 395 nGy h -1 . Radiological hazard parameters were studied and compared with the world average values. The contribution of 232 Th to the total dose rate was found to be higher than that of the two other radionuclides. The high mean ratio of 232 Th/ 226 Ra suggested an enrichment of 232 Th and the occurrence of 226 Ra leaching due to an oxidizing environment. Principal component analysis (PCA) was carried out for the radionuclides in order to discriminate the source of the sediments. This study provides new insights into the distribution of natural radionuclides in sediments of rivers and streams., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

A study on the activity concentration of primordial radionuclides 226Ra, 232Th and 40K was carried out on the surface soil samples collected from the coastal villages between Chhatrapur and Gopalpur regions of high background natural radiation area Odisha, India, using high purity germanium gamma spectroscopy. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 231, 1692 and 250 Bq/kg, respectively. The total mean absorbed dose owing to the presence of 226Ra, 232Th and 40K was 1139 nGy/h. The mean annual effective dose was found to be 1397 μSv/y and higher than the UNSCEAR average value 70 μSv/y., (© The Author(s) 2023. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. 238 U and 232 Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and 40 K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of 238 U, 232 Th and 40 K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of 238 U, 232 Th and 40 K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

90 Sr and 137 Cs activity concentrations were determined by radiometric methods in 76 soil samples (soil, litter, rain gutter deposit, and roadside sediment samples) affected by the Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident and collected from the Fukushima exclusion zone. The 90 Sr and 137 Cs activity concentrations were in the range of 3 to 1050 Bq kg -1 (median 82 Bq·kg -1 ) and 0.7 to 6770 kBq·kg -1 (median 890 kBq·kg -1 ), respectively (decay correction date: March 15, 2011). A strong positive correlation was found between 90 Sr and 137 Cs activity concentration and higher mobility of 90 Sr was confirmed in Japanese soil samples. The activity ratio of 90 Sr/ 137 Cs in 85% of all samples was in the range of 5.0 × 10 -5 to 5.0 × 10 -4 with a median of 1.2 × 10 -4 . From the activity ratio values it was concluded that the 90 Sr released to the atmosphere was only around 0.0003-0.02 PBq which is negligible compared to the Chernobyl accident (∼10 PBq) or other nuclear accident contaminations. From the standpoints of radioecology and radiation safety, 137 Cs remains the primary pollutant of the FDNPS accident., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A systematic mapping of natural absorbed dose rate was carried out to assess the existing exposure situation in India. The mammoth nationwide survey covered the entire terrestrial region of the country comprising of 45127 sampling grids (grid size 36 km 2 ) with more than 100,000 data points. The data was processed using Geographic Information System. This study is based on established national and international approaches to provide linkage with conventional geochemical mapping of soil. Majority (93%) of the absorbed dose rate data was collected using handheld radiation survey meters and remaining were measured using environmental Thermo Luminescent Dosimeters. The mean absorbed dose rate of the entire country including several mineralized regions, was found to be 96 ± 21 nGy/h. The median, Geometric Mean and Geometric Standard Deviation values of absorbed dose rate were 94, 94 and 1.2 nGy/h, respectively. Among the High Background Radiation Areas of the country, absorbed dose rate varied from 700 to 9562 nGy/h in Karunagappally area of Kollam district, Kerala. The absorbed dose rate in the present nationwide study is comparable with the global database., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The Fukushima soils have been collected from Namie and Futaba areas for the radiocaesium and uranium isotope ratio studies. The 137Cs activity concentration of soil samples ranged from 6 ± 1 to 756 ± 14 kBq/kg. The uranium isotope ratios are measured using multi collector inductively coupled plasma mass spectrometry. The activity ratio (234U/238U) of the Fukushima soils is calculated from the measured 234U/238U isotope ratio. Activity ratio varied from 0.98 to 1.02 which indicates that 234U and 238U are in secular equilibrium. The 235U/238U atomic ratio of the Fukushima soils did not show any heterogeneity compared with the natural terrestrial ratio even with high level of 137Cs in soils., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Various radionuclides including fission products and heavy nuclides were released into the environment during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The dissolution followed by migration of deposited radionuclides of Cs, Sr and U on soils could take place to the local environment. Therefore, it is necessary to determine sorption-desorption coefficients of U in soil-water system around the FDNPS from a migration viewpoint. The determination of sorption coefficient K d (S) as well as desorption coefficient K d (D) for U has been carried out in the present study using a laboratory batch method. Stable U was used for sorption from simulated ground water onto contaminated soil samples collected from Okuma Town, Fukushima. Different soil parameters were measured to understand their effects on sorption and desorption processes. The obtained K d (S) and K d (D) values of U were compared with values of K d (S) and K d (D) of Cs and Sr and K d (S)-U in known Fukushima accident contaminated soils reported in the literature for better understanding. It was observed that K d (S)-U varied from 160 to 5100 L/kg, whereas K d (D)-U ranged from 200 to 11000 L/kg. K d (D) was higher than K d (S) for U in these soils implying irreversibility of the sorption process. Pearson's correlation of K d (S) values suggested that U sorption is affected by various soil parameters. However, desorption is decided by the nature of U species formed in sorption process and soil parameters like pH, presence of carbonates, Ca ions, clay minerals etc. to some extent. The comparison between K d (S) and K d (D) values for Cs, Sr and U revealed that unsorbed Sr could migrate farther than unsorbed Cs or U under the present experimental conditions. Both sorption and desorption studies are of great importance to understand migration of metal ions from contaminated sites to local uncontaminated areas., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In the present study, 137 Cs and 238 U activity concentrations, 234 U/ 238 U activity ratio, and 235 U/ 238 U isotope ratio were measured in fifteen soil samples collected from the exclusion zone around the Fukushima Daiichi Nuclear Power Station (FDNPS). The 137 Cs activity concentrations of Fukushima-accident contaminated soil samples ranged from 29.9 to 4780 kBq kg -1 with a mean of 2007 kBq kg -1 . On the other hand, the 238 U activity concentrations of these soil samples ranged from 5.2 to 22.4 Bq kg -1 with a mean of 13.2 Bq kg -1 . The activity ratios of 234 U/ 238 U ranged from 0.973 to 1.023. The 235 U/ 238 U isotope ratios of these exclusion zone soil samples varied from 0.007246 to 0.007260, and they were similar to the natural terrestrial ratio confirming the natural origin. Using isotope dilution technique, the 235 U/ 137 Cs activity ratio was theoretically estimated for highly 137 Cs contaminated soil samples from Fukushima exclusion zone ranged from 5.01 × 10 -8 - 6.16 × 10 -7 with a mean value of 2.51 × 10 -7 ., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Soil radon (Rn-222) has been continuously monitored at Badargadh station (23.47°N, 70.62°E) in Kutch region of Gujarat to study the pre-seismic anomalies prior to occurrence of local earthquakes. This monitoring site is in close proximity to the South Wagad Fault, a seismically active fault in the study area. The raw data of radon along with meteorological parameters such as temperature, pressure and humidity in soil of this station for the period of January 01 to December 31, 2017 with a sampling interval of 10 min were used in the analysis. The wind speed and rainfall data of the corresponding period were collected from the nearest weather station. From descriptive statistics, we found an average soil radon concentration of 343 Bq.m -3 . It is observed that radon has a maximum concentration during the rainy season compared to the other two seasons. We found that radon emission rate is less during mid-nights and early morning, whereas, the radon emission is more during afternoon hours when the sun light intensity is more. In order to identify and extract the periodic oscillations in the radon time series, the Empirical Mode Decomposition (EMD) was applied to the soil radon (Rn-222) time series by decomposing it into different oscillatory modes known as the Intrinsic Mode Function (IMF). Several interesting non-linear features emerged from the analysis after applying Hilbert Huang Transform (HHT) on significant IMFs. The temporal variation of the instantaneous energy is well correlated with four local earthquakes during the study period. Most interestingly, intermittencies in the temporal evolution of the instantaneous energy function have been observed prior to these local earthquakes. We present the results of the seismic and aseismic periods as well as a brief discussion of the analysis of radon data which can be used as a precursor of seismic activity. It is now possible to identify anomalies in radon time series using EMD based HHT method even for small-magnitude earthquakes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Owing to their natural radioactivity, uranium (U) and thorium (Th) play significant roles in environmental sciences for monitoring radiation dose and in geological sciences for understanding sedimentary processes. The Odisha coastal area, in eastern India, is a well-known high background radiation area that is rich in monazites and rutile. This area was selected to study geochemical characteristics of U and Th in sand and sandy soil samples. The concentrations of U and Th were measured using inductively coupled plasma mass spectrometry (ICP-MS). The median, geometric mean, and standard deviation for U were determined to be 6, 4.5, and 2.5 μg/g and for Th were 186, 123.3, and 3.1 μg/g, respectively. Major element concentrations were evaluated using X-ray fluorescence spectroscopy to get the mineralogical composition and state of chemical weathering. The ratios of Th/U and Th/K varied from 4 to 37 and from 13 to 1058, respectively. These results clearly indicate that the samples from the coastal region were formed in an oxidizing and intense chemical weathering terrestrial environment with an enrichment of radiogenic heavy minerals (monazites and zircon) and clay mineral association. Since the majority of the samples have undergone moderate to intense weathering in the oxidizing environment, U is leached from the soil and sand matrix. Eventually, Th resides in the matrix and becomes a major source for radiation exposure in the environment. The high ratios of Th/U, along with the strong positive correlation between Th and P 2 O 5 , evidence the enrichment of the Th-bearing radioactive mineral, monazite, in these samples.

A preliminary study was carried out to determine the radioactivity concentration of 232Th, 226Ra and 40K in beach placer sands from 13 locations along the coast line of Tamil Nadu state, India. The ambient dose rates varied from 9 to 467 nGy h-1. The activity concentrations of radionuclide 232Th, 226Ra and 40K ranged from 5.2 to 683 Bq kg-1, 13 to 198 Bq kg-1 and 107 to 421 Bq kg-1, respectively. The annual effective dose rate ranges from 27 to 620 μSv y-1 and was higher at seven beaches in comparison to the UNSCEAR annual worldwide average value., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Uranium, thorium and rare earth elements (REEs) in soil samples contaminated by Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident was determined using inductively coupled plasma-mass spectrometry (ICP-MS). This information provides knowledge about concentration levels of REEs in soil samples as a background data after FDNPP accident. Chondrite-normalised REEs pattern does not show enrichment in concentrations of REEs, which could be related to FDNPP accident. The high concentration of these elements at few sampling points may be due to soil formation process from granitic rocks., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted radioactive contamination in soil due to deposition of mainly radiocesium as well as many long-lived radionuclides surrounding a large area around FDNPP. Depending upon environmental conditions, radionuclides in soil can be mobilized in aquatic systems. Therefore, the fate and transfer of these radionuclides in the soil water system is very important for radiation protection and dose assessment. In the present study, soil and water samples were collected from contaminated areas around FDNPP. Inductively coupled plasma mass spectrometry (ICP-MS) is used for total uranium concentration. Emphasis has been given on isotope ratio measurement of 235 U/ 238 U ratio using thermal ionization mass spectrometry (TIMS) that gives us the idea about its contamination during accident. For the migration behavior, its distribution coefficient (K d ) has been determined using laboratory batch method. Chemical characterization of soil with respect to different parameters has been carried out. The effect of these soil parameters on distribution coefficient of uranium has been studied in order to explain the radionuclide mobility in this particular area. The distribution coefficient values for uranium are found to vary from 30 to 36000 L/kg. A large variation in the distribution coefficient values shows the retention or mobility of uranium is highly dependent on soil characteristics in the particular area. This variation is explained with respect to soil pH, Fe, Mn, CaCO 3 and organic content. There is a very good correlation of uranium K d obtained with Fe content. There is no enrichment of 235 U has been noticed in the studied area., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A comprehensive study was carried out to determine the radioactivity concentration of soil samples from different sites of a high background radiation area in the eastern coast of India, Odisha state. The dose rate measured in situ varied from 0.25 to 1.2 µSv h -1 The gamma spectrometry measurements indicated Th series elements as the main contributors to the enhanced level of radiation and allowed the authors to find the mean level of the activity concentration (±SD) for 226 Ra, 228 Th and 40 K as 130±97, 1110±890 and 360±140 Bq kg -1 , respectively. Human exposure from radionuclides occurring outdoor was estimated based on the effective dose rate, which ranged from 0.14±0.02 to 2.15±0.26 mSv and was higher than the UNSCEAR annual worldwide average value 0.07 mSv. Additionally, X-ray fluorescence analysis provided information about the content of major elements in samples and indicated the significant amount of Ti (7.4±4.9 %) in soils., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The radioactive fission product (90)Sr has a long biological half-life (˜18 y) in the human body. Due to its chemical similarity to calcium it accumulates in bones and irradiates the bone marrow, causing its high radio-toxicity. Assessing (90)Sr is therefore extremely important in case of a nuclear disaster. In this work 16 soil samples were collected from the exclusion zone (<30 km) of the earthquake-damaged Fukushima Daiichi nuclear power plant, to measure (90)Sr activity concentration using liquid scintillation counting. (137)Cs activity concentration was also measured with gamma-spectroscopy in order to investigate correlation with (90)Sr. The (90)Sr activity concentrations ranged from 3.0 ± 0.3 to 23.3 ± 1.5 Bq kg(-1) while the (137)Cs from 0.7 ± 0.1 to 110.8 ± 0.3 kBq kg(-1). The fact that radioactive contamination originated from the Fukushima nuclear accident was obvious due to the presence of (134)Cs. However, (90)Sr contamination was not confirmed in all samples although detectable amounts of (90)Sr can be expected in Japanese soils, as a background, stemming from global fallout due to the atmospheric nuclear weapon tests. Correlation analysis between (90)Sr and (137)Cs activity concentrations provides a potentially powerful tool to discriminate background (90)Sr level from its Fukushima contribution.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the deposition of radioactive contamination of soils mainly by (134)Cs and (137)Cs. The contaminated areas are of a great concern since external radiation may lead to significant long-term doses to humans and animals. External dose rate above ground will decrease with physical decay of the radionuclides and as they migrate deeper into the soil with time. In the present study, depth profiles of Cs radioisotopes have been studied at different times over a period of 1 y. Radiocaesium inventories for (134)Cs and (137)Cs down to a depth of 10 cm at the four measurement times varied from 2.09 to 4.14 MBq m(-2) with coefficient of variation (CV): 27.4 %, n = 4 and from 2.13 to 4.23 MBq m(-2) with CV: 27.3 %, n = 4, respectively. The activity ratio for (134)Cs/(137)Cs decreased from 0.62 to 0.46 during 1 y of measurement i.e. July 2012 to June 2013. However, the ratio with decay correction (15 March 2011) was found to be constant ∼1, indicating contamination from FDNPP origin. In order to understand the radiocaesium distribution in soil profile, physico-chemical characterisation of soil has been carried out., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Radon ((222)Rn) emanation coefficients for the representative soils distributed in Okinawa Island, Japan, have been estimated empirically. Arithmetic means of the emanation coefficients for dry and moist conditions were calculated to be 0.19 and 0.29, respectively. In Okinawa, the soils are traditionally classified into three types, namely the dark red soils, the residual regosols and the red and yellow soils. The dark red soils have relatively high coefficients. The residual regosols and the red and yellow soils have relatively low coefficients. To investigate the variable factor of the emanation coefficients, analyses of radioactive elements and physical properties have also been performed on the soils. For the dark red soils, the contents of the fine particle and the (226)Ra are relatively higher than those for the other soils. Based on these results, it is suggested that the variation in the radon emanation coefficient is mainly regulated by the (226)Ra concentration, the particle sizes and the water contents of the soils., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

A method based on liquid scintillation counting system has been developed for the measurement of (90)Sr in Fukushima soil samples due to contamination of (134)Cs and (137)Cs. Three soil samples were collected within 30 km radius from the Fukushima Daiichi Nuclear Power Plant (FDNPP). Activity concentration of (134)Cs and (137)Cs were measured using a gamma spectroscopy system with high-purity germanium detector. (90)Sr contamination is little elevated but comparable with the background contamination level that originated from atmospheric nuclear weapon tests, whereas radiocesium contamination has increased significantly. Activity concentration of (90)Sr in the soil samples varied in the range of 10.4±0.6-22.0±1.2 Bq kg(-1). Activity concentrations of (134)Cs and (137)Cs in the soil samples were in the range of 28.2±0.2-56.3±0.2 kBq kg(-1) and 35.2±0.1-70.2±0.2 kBq kg(-1), respectively (reference date for decay correction is 1 December 2011)., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The specific activity of naturally occurring radioactive materials and (137)Cs in surface soils around the new Bhabha Atomic Research Centre site at Visakhapatnam region, Eastern India, has been determined using high-resolution gamma-ray spectrometry as part of a baseline radiological survey. Radiation hazard for the samples was assessed by radium equivalent activity (Raeq) and absorbed gamma dose rate (D). The mean absorbed gamma dose rate was found to be 104.9 nGy h(-1). The average annual effective dose equivalent was found to be 0.13 mSv y(-1).

Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of (238)U, (226)Ra, (232)Th, (235)U, (227)Th, (234 m)Pa, (210)Pb, (40)K, and (137)Cs were 79 ± 50, 81 ± 53, 65 ± 23, 4 ± 2, 5 ± 4, 92 ± 50, 97 ± 45, 517 ± 201, and 4 ± 2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of (226)Ra/(238)U, (210)Pb/(226)Ra, and (227)Th/(235)U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12 ± 0.04 mSv for this region, indicating it to be one of normal natural background radiation.

Sorption-desorption behaviour of uranium (U), cesium (Cs) and strontium (Sr) was examined by quantification of the solid-liquid distribution coefficients (K(d)) using batch method in typical podzol soils from Ukraine. The effect of different physico-chemical parameters of soil on K(d) values has been discussed. Sorption reversibility has been tested by single extraction test. U shows reversible sorption and there was no isotopic fractionation observed with a known isotopic U composition using as tracer. Cs sorption mostly occurred in an irreversible manner. The clay content and exchangeable potassium in soil play an important role in Cs fixation. Sr adsorption is observed to be reversible and mainly controlled by cation exchange and shows highest mobility in the soil-water system. The K(d) values are found in the decreasing order U (log K(d) ≈ 2-3) > Cs (log K(d) ≈ 2) > Sr (log K(d) ≈ 1).

Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides (226)Ra, (232)Th and (40)K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of (226)Ra, (232)Th and (40)K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of (226)Ra, (232)Th and (40)K ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view.

Radon and thoron exhalation rates from the ground surface were estimated in three islands of Okinawa Prefecture, a subtropical region of Japan. In situ measurements of the exhalation rates were conducted at a total of 88 points using an accumulation technique with a ZnS(Ag) scintillation detector. The radon and thoron exhalation rates were calculated to be 1-137 (arithmetic mean: 21) mBq m(-2) s(-1) and 32-6244 (1801) mBq m(-2) s(-1), respectively. In the surface soil samples collected at 53 measurement points, (238)U and (232)Th series concentrations were estimated to be 17.9-254.0 (64.0) Bq kg(-1) dry and 17.8-136.1 (58.8) Bq kg(-1) dry, respectively. The maximum rates and concentrations were observed in the dark red soil area. Recent studies strongly suggest that the base material of the soils may be the eolian dust derived from the southeastern part of China, a high background radiation area. The eolian dust is, therefore, considered to be an enhancer for the radon and thoron exhalations in Okinawa.

The present work deals with the prevalent radiological scenario around uranium-mining sites in the Singhbhum East district of Jharkhand state, India. The concentration of naturally occurring radioactive materials (NORMs) was estimated from 27 soil samples collected around three regions in the study area, namely Bagjata, Turamdih and Jaduguda. The mean activity concentrations of (238)U in Bagjata, Turamdih and Jaduguda regions were found to be 128.6, 95.7 and 49.2 Bq kg(-1), respectively. Similarly for (232)Th and (40)K the activity concentrations were found to be 57.3, 78.4, 68.9 and 530, 425 and 615 Bq kg(-1) in the Bagjata, Turamdih and Jaduguda regions, respectively, which are comparable with other reported values worldwide, except for some high values. The calculated gamma dose rate, obtained from the concentrations of (238)U, (232)Th and (40)K in the samples, was compared with the observed dose rate in air. A good correlation (0.96) was observed between the calculated and the observed gamma dose rate. The annual outdoor effective dose rate was estimated and the values falls between 0.04-0.3, 0.07-0.3 and 0.07-.14 mSv y(-1) with mean values of 0.14, 0.12 and 0.11 mSv y(-1) for the Bagjata, Turamdih and Jaduguda regions, respectively. The terrestrial dose rates in all the three regions are comparable with other reported values worldwide, except for a few high values in Greece, Rio Grande Do Norte (Brazil) and Kalpakkam (India).

The specific activity and the gamma radiation dose rates due to naturally occurring radioactive materials ((238)U, (232)Th and (40)K) were determined in 26 roadside surface soils along Jamshedpur-Musabani road-a mineralised and mining region, using high-resolution gamma-ray spectrometry. The concentrations of (238)U, (232)Th and (40)K in the soil samples were found to be in the range of 16.6 +/- 0.6-390.5 +/- 1.6, 24.1 +/- 0.7-148.2 +/- 2.1 and 85.9 +/- 3.8-881.6 +/- 22.4 Bq kg(-1), respectively. The annual effective dose equivalent was found to be in the range of 0.04-0.32 mSv y(-1) with an average value of 0.13 mSv y(-1). The excess cancer risk is in the range of 0.16 x 10(-3)-1.22 x 10(-3) with an average value of 0.49 x 10(-3).

A large amount of radioiodine isotopes (mainly (131)I, t(1/2) = 8 days) was released from the accident at Chernobyl Nuclear Power Plant (CNPP) in April-May 1986. An increase in childhood-thyroid cancer in the contaminated areas in Belarus, Russia and the Ukraine was demonstrated to be caused by radioiodine released at the time of the accident. However, there is a lack of quantitative data on the (131)I levels in the local environment (e.g. air, plant, soil). At this point, a long-lived iodine isotope, (129)I (t(1/2) = 15.7 million years), also released with a certain ratio to (131)I from CNPP, could be used for estimating the (131)I levels in the environment. In this paper we present analytical results of the (129)I concentrations and (129)I/(127)I atom ratios in soil samples collected from the CNPP exclusion zone (30-km zone), with the aim of assessing current contamination levels and distribution patterns. For the analysis of the iodine fraction in the investigated soil samples, the pyrohydrolysis method was utilized for separation of (127)I and (129)I nuclides, and subsequently their concentration was determined using inductively coupled plasma mass spectrometry (ICP-MS) and accelerator mass spectrometry (AMS), respectively. The concentration of (129)I and the (129)I/(127)I atom ratio in the surface soil samples in the 30 km-zone of CNPP ranged from 4.6 to 170 mBq/kg, and from 1.4 x 10(-6) to 13 x 10(-6), respectively. These values are significantly higher than those from global (129)I fallout, indicating that most of the measured (129)I was due to the deposition of the accident. Stable iodine concentrations in this area were found to be very low (below 1 ppm) for most of the samples, suggesting the environmental iodine levels in this area to be potentially low. The (129)I/(137)Cs activity ratio in surface and sub-surface soils was not so constant, i.e., in the range (7.3-20.2) x 10(-7). This might be due to the different behavior of deposition and/or migration of these nuclides in soil. These results suggest the obtained data of (129)I to be useful for the reconstruction of the (131)I deposition in the contaminated areas.

Based on results of fieldwork in the Balkan Region of Serbia from 2005 to 2007, soil gas radon and thoron concentrations as well as gamma dose rates were measured. Campaigns were conducted in two different geological regions: Niska Banja, considered a high natural radiation area, and Obrenovac around the TentB Thermal Power Plant (TPP), a low natural radiation area. Radon and thoron gas measurements were made by using two types of Japanese passive radon/thoron detectors, which included GPS data and gamma dose rates. The concentrations of soil radon gas in Niska Banja ranged from 1.8 to 161.1 kBq m(-3), whereas the concentrations for soil thoron gas ranged from 0.9 to 23.5 kBq m(-3). The gamma dose rates varied from 70 to 320 nGy h(-1). In the TentB area, radon concentration was found to range from 0.8 to 24.9 kBq m(-3) and thoron from 0.6 to 1.9 kBq m(-3). The gamma dose rate ranged from 90 to 130 nGy h(-1). In addition, the natural radioactivity of the soil was investigated at the low background area. The radium and thorium contents in collected soil samples ranged from 23 to 58 and 33 to 67 Bq kg(-1), respectively. As a result of correlation analyses between the measured values, the highest correlation coefficient (R > 0.95) was found for thorium in the soil and the thoron gas concentration.

We simultaneously measured radon and thoron exhalation rates in areas of weathered acid rocks in Japan to investigate the relationship between them and between measured and calculated radon exhalation rates. To calculate the radon exhalation rate, we used an equation proposed by UNSCEAR. Our analysis showed that both the radon and thoron exhalation rates measured at one location in a natural environment fluctuated widely, even within one day. We found a strong correlation between the radon and thoron exhalation rates. The measured radon exhalation rates tended to be lower than the calculated values: the mean ratio of the measured exhalation rate to the calculated rate was 0.65. We concluded that the UNSCEAR equation is applicable under a controlled environment (temperature, humidity, etc.), but not where there are artificial underground structures that may influence the transportation of radon in soil.