Distribution of <Superscript>137</Superscript>Cs, <Superscript>40</Superscript>K, <Superscript>232</Superscript>Th and <Superscript>238</Superscript>U in coastal marine sediments of Margarita Island,Venezuela

This work presents the results of ¹³⁷Cs, ⁴⁰K, ²³²Th and ²³⁸U concentration (Bq kg⁻¹) values in coastal marine sediments collected from 38 sites along the coastline of the island of Margarita, Venezuela. The purpose was to determine baseline values for these radionuclides in surface marine sediments and to detect if there were any anomalously high concentration values. Only three of the 38 sediments analyzed had measurable values above the detection limit of 0.9 Bq kg⁻¹ for ¹³⁷Cs and the highest only being 1.4 Bq kg⁻¹. While, the concentration (Bq kg⁻¹) ranges for the primordial radionuclides, ⁴⁰K, ²³²Th and ²³⁸U were as follows: 12.2–211.7, <1.5–9.8 and <4.4–20.7, respectively. These concentration ranges for the primordial radionuclides can be considered as baseline values for surface marine sediments for areas that are considered not polluted by man or contaminated by nature. Finally, the concentration range of ¹³⁷Cs can also be employed as baseline values, which only seem to have been the result of the atmospheric testing of nuclear weapons in the past.     

Radiological assessment of natural and fallout radioactivity in the soil of Chamba and Dharamshala areas of Himachal Pradesh,India

This paper presents the results of measurement of natural and fallout radioactivity in soil samples of Chamba and Dharamshala areas in Himachal Pradesh, India. Spatial distribution of ²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K, ¹³⁷Cs was determined using High resolution gamma-ray spectrometry. The mean activity concentration in Chamba region due to ²³⁸U, ²³²Th, ⁴⁰K and ¹³⁷Cs was 32.3, 58.4, 588.3, and 10.9 Bq kg⁻¹, respectively, whereas in Dharamshala it was 35.7, 61.3, 594.9, 10.0 Bq kg⁻¹, respectively. Absorbed gamma dose rate (D) in air was calculated using appropriate dose conversion factors, which was varying from 45 to 103 nGy h⁻¹. To control the radiation exposure due to natural radioactivity in soil, if it is used as building materials, radium equivalent activity (Ra_eq) and activity index were also evaluated. Radium equivalent activity calculated for the soil ranged from 95.5 to 234.2 Bq kg⁻¹ with average of 171.0 Bq kg⁻¹.The calculated Activity concentration index was ranged from 0.34 to 0.85 with an average value of 0.64. The natural and fallout radioactivity in soil of this region is comparable with Indian average and other parts of the world. The percentage contribution of ²³⁸U, ²³²Th and ⁴⁰K and ¹³⁷Cs to the average external gamma dose rate was 22, 46, 32, 2%, respectively. This shows that the dose contribution due to fallout radioactivity is negligible as compared to the natural radioactivity.     

Measurement of naturally occurring/fallout radioactive elements and assessment of annual effective dose in soil samples collected from four districts of the Punjab Province,Pakistan

Soil samples were collected from different localities of districts Jhelum, Chakwal, Rawalpindi and Attock, Punjab Province, Pakistan with an aim to measure naturally occurring radionuclides, namely ²²⁶Ra, ²³²Th, ⁴⁰K and fallout ¹³⁷Cs radionuclide using a P-type coaxial high purity germanium (HPGe) γ-ray spectrometer. Measured specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K in these soil samples ranged from 26.02 ± 7.11 to 93.54 ± 8.13 Bq kg⁻¹, 29.34 ± 2.58 to 114.41 ± 2.80 Bq kg⁻¹ and 348.15 ± 3.20 to 752.98 ± 4.20 Bq kg⁻¹, respectively. Activity due to ¹³⁷Cs was observed in some locations which ranged from 0.4 ± 0.2 to 7.8 ± 0.3 Bq kg⁻¹. From the measured activity concentrations, radium equivalent activity concentrations were determined followed by calculations of mean absorbed dose rate and mean annual effective dose for the inhabitants of the studied area. The mean radium equivalent activity, internal and external hazard indices values came out to be 179.26 ± 11.93 Bq kg⁻¹, 0.64 ± 0.05 and 0.48 ± 0.03, respectively. Indoors and outdoor average annual effective dose values were found to be 0.42 ± 0.03 and 0.10 ± 0.01 mSv, respectively. Present data have been compared with the published data for other parts of the world and found to be safe for public and environment.     

Measurement of soil radioactivity levels and radiation hazard assessment in mid Rechna interfluvial region,Pakistan

Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using gamma ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg⁻¹ respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg⁻¹, 0.51, 0.65 and 70.1 nGy h⁻¹ respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment.     

Assessment of natural radioactivity in silt samples from Moticher lake near Kakrapar Atomic Power Station,India

The naturally occurring radioisotopes such as ²³⁸U, ²³²Th and ⁴⁰K in the silt samples collected from Moticher lake, Gujarat were evaluated. The activity of ²³⁸U, ²³²Th and ⁴⁰K was found to be 4.4-9.7 Bq kg⁻¹ with a mean 6.4 ± 1.3 Bq kg⁻¹, 10.5–21.2 Bq kg⁻¹ with a mean 15.6 ± 2.5 Bq kg⁻¹ and 102–231 Bq kg⁻¹ with a mean 160 ± 40 Bq kg⁻¹, respectively. The depth profile study could not reveal any significant vertical correlation on radioactivity levels of ²³⁸U, ²³²Th and ⁴⁰K. Radium equivalent activity (Ra_eq), external hazard index (H _ex) and internal hazard index (H _int) were calculated by using the activity of ²³⁸U or ²²⁶Ra, ²³²Th and ⁴⁰K in silt samples. Annual Effective Dose Equivalent (AEDE) level in Moticher silt was found to be 24.8 ± 5.0 μSv year⁻¹, which is much lower than the worldwide average value. The relative contribution to dose due to ²³⁸U and ²³²Th series were found to be 14% and 53%, followed by the contribution of 33% due to ⁴⁰K.     

Radioactivity concentrations in sediment and mussel of Bosphorus and Golden Horn

In the present study, mussel (Mytilus galloprovincialis, Lamarck, 1819) and sediment samples were collected from the Bosphorus strait and the Golden Horn estuary in 2008 and 2009. Activity concentrations of ¹³⁷Cs, ⁴⁰K, ²³²Th and ²³⁸U were measured using a gamma spectrometer equipped with HPGe detector. Sediment samples were separated into <63 μm and >63 μm particle fractions. Analysis of radionuclides was carried out on these two fractions of sediment as well as the soft and shell tissues of mussels. Ranges of radioactivity concentrations in the soft parts of mussels were as follows: ¹³⁷Cs, 0.86–2.43; ⁴⁰K: 261.1–496.7; ²³²Th: 0.49–3.58; and ²³⁸U: BDL (below detection limit)-1.38 Bq kg⁻¹ in dry weight. Ranges of radioactivity concentrations in the <63 and >63 sediment fractions were as follows: ¹³⁷Cs, 8.58–67.92 and 1.12–26.40, ⁴⁰K, 341.4–683.0 and 281.9–662.2; ²³²Th, 10.97–20.16 and 7.18–19.18 and ²³⁸U, 13.97–27.25 and 6.41–18 Bq kg⁻¹ in dry weight, respectively. The effect of some physical–chemical parameters on the radionuclide accumulation was also examined in the sediment samples. All data in the current study were compared with data in the literature.     

Depth profile study of natural radionuclides in the environment of coastal Kerala

The present work investigated the activity concentrations of natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in beach sand samples along coastal Kerala including high background radiation area. The activity of ²³²Th ranges from below detectable level to 23029.9 Bq kg⁻¹ with a mean value of 2660.2 Bq kg⁻¹ for 0–10 cm depth interval. For 10–20 cm depth, the ²³²Th activity ranged from below detectable to 4452.2 Bq kg⁻¹ with a mean value of 815.5 Bq kg⁻¹. The variation of ²²⁶Ra activity with depth is parallel with the ²³²Th activity distribution in beach sand. Its activity varied from below detectable to 5169.5 Bq kg⁻¹ with a mean value 487.6 Bq kg⁻¹ at 0–10 cm depth. For 10–20 cm depth interval, the ²²⁶Ra activity ranges from below detectable to 1823.6 Bq kg⁻¹ with a mean value 296.0 Bq kg⁻¹. Similarly the activity varies from below detectable to 1826.6 Bq kg⁻¹ with a mean value of 211.0 Bq kg⁻¹ for a depth interval of 20–30 cm. The activity of ⁴⁰K at different depth is also discussed. Statistical analysis of radioactivity was also carried out. The results of these investigations are presented in this paper.     

Assessment of natural radioactivity in soil samples and comparison of direct and indirect measurement of environmental air kerma rate

This study presents the high purity germanium (HPGe) gamma spectrometric measurement of natural radioactivity mainly due to ²²⁶Ra, ²³²Th and ⁴⁰K in soil samples collected in Ferozepur and Faridkot district of Punjab, India. ²²⁶Ra activity varied from 28.6 to 51.1 Bq kg⁻¹ with the mean of 39.7 Bq kg⁻¹. The range and mean activity of ²³²Th were 42.9–73.2 and 58.2 Bq kg⁻¹, respectively. ⁴⁰K activity was in the range of 470.9–754.9 Bq kg⁻¹ with the mean of 595.2 Bq kg⁻¹. The air kerma rate (AKR) at 1 m height from the ground was also measured using gamma survey meter in all the sampling locations, which was ranging from 92.1 to 122.8 nGy h⁻¹ with the mean of 110.6 nGy h⁻¹. The radiological parameters such as Ra_eq and activity index of the soil samples were also evaluated, which are the tools to assess the external radiation hazard due to building materials. The mean and range of the Ra_eq values were 168.7 and 132.9–210.4 Bq kg⁻¹, respectively, whereas the activity index varied from 0.5 to 0.8 with the mean value of 0.62. These indices show that the indoor external dose due to natural radioactivity in the soil used for the construction will not exceed the dose criteria. The AKR was also evaluated from soil activity concentration and altitude correction of cosmic radiation contribution. The statistical tests such as Pearson correlation, spearman rank correlation, box and whisker plot, the Wilcoxon/Mann–Whitney test and chi-square test, were used to compare the measured AKR with evaluated AKR, which indicates good correlation.     

A study on 210Po activity concentration in soil at different depths along coastal Kerala

The paper presents systematic studies on the vertical profiles of ²¹⁰Po, an important decay product of ²³⁸U, in soils along coastal Kerala. Soil samples collected from different depth intervals 0–10, 10–20, 20–30 cm were analyzed for ²¹⁰Po activity concentration by radiochemical methods. The activity ²¹⁰Po in soil samples were counted using a ZnS(Ag) alpha scintillation counting system. The mean values of activity concentrations of ²¹⁰Po in soil of various depths were found to be 8.66, 5.63 and 4.95 Bq kg⁻¹ for depth intervals of 0–10, 10–20 and 20–30 cm, respectively. The overall activity concentration of ²¹⁰Po in soil was found to vary from 2.26 ± 0.19 to 14.02 ± 0.12 Bq kg⁻¹ with a mean value of 6.43 Bq kg⁻¹. Maximum activity concentration was found in soil samples of Kollam region with the mean value of 10.08 ± 0.92 Bq kg⁻¹. The activity of ²¹⁰Po was found to be comparatively high in surface soil. The variation of ²¹⁰Po activity concentration with organic matter contents was studied. ²¹⁰Polonium activity concentration was found to increase with increasing organic matter content.     

Determination of naturally occurring radionuclides in selected rocks from Hetaunda area,central Nepal

The specific activities of the naturally occurring radionuclides ²³⁸U, ²³²Th, and ⁴⁰K were measured in rock samples from the Hetaunda area, central Nepal, using gamma spectrometry. The specific activities were found to be in the range of 17–95 Bq kg⁻¹ for ²³⁸U, 24–260 Bq kg⁻¹ for ²³²Th and 32–541 Bq kg⁻¹ for ⁴⁰K. From these data absorbed dose rates in air and annual effective doses were calculated and compared with respective data from the UNSCEAR compilation. The results from our study open the door to the safe applicability of most of the investigated materials as a cheep building material.     

Levels of <Superscript>232</Superscript>Th activity in the South Adriatic Sea marine environment of Montenegro

²³²Th activities in the South Adriatic Sea-water, surface sediment, mud with detritus, seagrass (Posidonia oceanica) samples, and the mullet (Mugilidae) species Mugil cephalus, as well as soil and sand from the Montenegrin Coast, were measured using the six-crystal spectrometer PRIPYAT-2M, which has relatively high detection efficiency and a good sensitivity, and allows a short acquisition time, and measuring samples of any shape, without preliminary preparation and calibration measurements for different sample geometries. An average ²³²Th activity concentration in surface soil layer is found to be 40.33 Bq kg⁻¹, while in sand—4.7 Bq kg⁻¹. The absorbed dose rate in air due to ²³²Th gamma radiation from surface soil layer ranged from 11.76 to 63.39 nGy h⁻¹, with a mean of 24.06 nGy h⁻¹. Corresponding average annual effective dose rate has been found to be 0.03 mSv y⁻¹. The absorbed dose rates due to the thorium gamma radiation in air at 1 m above sand surface on the Montenegrin beaches have been found to be from 0.41 to 9.08 nGy h⁻¹, while annual effective dose rates ranged from 0.0005 to 0.011 mSv y⁻¹. ²³²Th activity concentration in seawater ranged from 0.06 to 0.22 Bq L⁻¹, as in the mullet (Mugil cephalus) whole individuals from 0.63 to 1.67 Bq kg⁻¹. Annual intake of ²³²Th by human consumers of this fish species has been estimated to provide an effective dose of about 0.003 mSv y⁻¹.     

Ultra low level deep water <Superscript>137</Superscript>Cs activity in the South Pacific Ocean

We determined ¹³⁷Cs concentrations in deep water samples of the subtropical gyre in the South Pacific collected during the BEAGLE2003 cruise. This was done at an underground facility to achieve extremely low background γ-spectrometry, and we, therefore, obtained reliable values of ¹³⁷Cs activity in the deeper layers. ¹³⁷Cs activity in the layers between 2000 and 4500 m ranged from 7 ± 4 mBq m⁻³ to 25 ± 11 mBq m⁻³. The inventory of ¹³⁷Cs in the water column from 2000 m to the sea bottom was estimated to be 20 ± 8 Bq m⁻² to 94 ± 41 Bq m⁻² in this region.     

Transfer of uranium and thorium from soil to different parts of medicinal plants using SSNTD

The uptake of ²³⁸U and ²³²Th in different parts of some selected plants used in traditional treatment of hypertension and diabetes in south-eastern Morocco (Errachidia area) has been studied using two different types of solid state nuclear track detectors (SSNTDs) LR-115 type II and CR-39. Plant uptake of radionuclides is one of many vectors for introduction of contaminants into the human food chain. Thus, it is critical to understand soil–plant relationships that control nuclide bioavailability. Soil concentrations of uranium ranged from 6.10 to 11.62 ppm, with a mean of 7.90 ppm. Soil concentrations of thorium ranged from 2.70 to 4.80 ppm, with a mean of 3.41 ppm. Mean uranium specific activities were 8.38 Bq kg⁻¹ in root tissue, 5 Bq kg⁻¹ in stem tissue and 6.02 Bq kg⁻¹ in leaf tissue. Mean thorium specific activities were 2.53 Bq kg⁻¹ in root tissue, 1.64 Bq kg⁻¹ in stem tissue and 1.96 Bq kg⁻¹ in leaf tissue. The transfer factors of ²³⁸U and ²³²Th from soil to different parts (root, stem, leaf, seed and fruit) of studied plant samples have been investigated. The transfer factors obtained for root plants were markedly higher than those for leaf, stem, fruit and seed plants. Soil-to-plant transfer factor (TF) is one of the most important parameters to be used in transfer models for predicting the concentration of radionuclides in agricultural crops and for estimating dose impacts to man. This study of uranium and thorium uptake in plants used in traditional medicine is also significant as far as the health hazard effects of uranium and thorium in human being are concerned.     

External dose-rates for natural gamma emitters in soils from an agricultural land in West Anatolia

The surveys of natural gamma-emitting radionuclides in soils from three basins of West Anatolia intensively used for agricultural purposes were conducted during 1998–2003. In the present study, part of the survey, the activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K in the soil samples from 43 sites distributed all over the agricultural land known as Büyük Menderes basin were determined by scintillation gamma spectrometry. The average activity concentrations and ranges of the relevant radionuclides in the soils were as follows: ²³⁸U was 29 (7–84); ²³²Th, 22 (10–48) and ⁴⁰K, 464 (100–864) Bq kg⁻¹. The corresponding absorbed dose rates in air from all those radionuclides were in the range of 17–81 nGy h⁻¹ with a mean value of 46 nGy h⁻¹ and did not exceed the world-wide average values. All dosimetric calculations were performed based on the guidance of UNSCEAR 2000 report [1].     

Geographical and vertical distribution of radiocesium levels in coniferous forest soils in Izmir

Preliminary picture of ¹³⁷Cs radioactivity levels in forested areas in and around Izmir is illustrated. Both activity concentrations and activity depositions of ¹³⁷Cs in soil samples were determined. Their values varied from 8.29±0.27 to 445±3.16 Bq.kg⁻¹ (d.w.) and 0.63±0.01 to 11.6±0.08 kBq.m^–2 (d.w.), respectively. It was found that while activity deposition of ¹³⁷Cs is normally distributed, activity concentration of ¹³⁷Cs is log-normally distributed in forest soils and the activity deposition is less variable than the activity concentration. Cesium-137 activities in soils increase with increasing elevation, annual average rainfall and soil organic matter.     

Seasonal changes of 137Cs in benthic plants from the southern Baltic Sea

¹³⁷Cs activity concentrations were determined in samples of macrophytes Polysiphonia fucoides (red algae) and Zostera marina (vascular plant) collected during the entire vegetation season in the Gulf of Gdańsk in the southern Baltic Sea. The measurements showed considerable seasonality of ¹³⁷Cs activity in both species; an increase of cesium concentrations was observed from spring to autumn with maximal levels 49.1 ± 1.4 Bq kg_d.w.⁻¹ (P. fucoides) and 14.5 ± 1.0 Bq kg_d.w.⁻¹ (Z. marina) in late autumn. ¹³⁷Cs concentrations observed in a given season are the result of a number of processes, the intensity of which can differ depending on external environmental conditions. The effects of these processes can differ and their directions can frequently be opposite to one another. The examined macrophytobenthic plant species could serve as bioindicators of radionuclide pollution for monitoring purposes on condition that the samples of plants are taken within a strictly defined period of the year to give comparable results and to supply realistic information about pollution levels.     

Concentration factors for 226Ra in the mullet (Mugilidae) species Mugil cephalus from the South Adriatic Sea

²²⁶Ra activity concentration in the mullet (Mugilidae) species Mugil cephalus whole individuals, and some organs (gills, gastrointestinal system, fins, muscle and bones), was measured by the γ-coincidence spectrometer PRIPYAT-2M. ²²⁶Ra transfer parameters [concentration factors (CFs)] from seawater, sediment and mud with detritus to fish tissues, and annual intake by humans consuming this fish species, have been estimated. Minimum detected radium activity concentration in whole M. cephalus individuals was found to be 0.89 ± 0.42 to 3.09 ± 0.41 Bq kg⁻¹, with arithmetic mean of 1.65 ± 0.39 Bq kg⁻¹. An average concentration in muscles is found to be 2.28 ± 0.84 Bq kg⁻¹, in gills—5.02 ± 1.85 Bq kg⁻¹, in gastrointestinal system—12.88 ± 1.71 Bq kg⁻¹, and in bones—14.72 ± 3.75 Bq kg⁻¹. No one fins showed radium activity above minimum detectable one. Annual intake of ²²⁶Ra by human consumers of this fish species is estimated to provide an effective dose of 0.006 mSv year⁻¹. CFs for ²²⁶Ra indicating transfer from seawater to whole individuals ranged from 8.9 to 30.9, and those indicating transfer from the sediment and mud with detritus—from 0.11 to 0.39 and from 0.08 to 0.3, respectively. The seawater to bones CFs varied from 97.9 to 197.3, to gastrointestinal system—from 59 to 178.8, to gills—from 22.5 to 68.3, to muscles—from 17 to 30.8.     

Measurement of the radioactivity of 238U, 226Ra, 210Pb, 228Th, 232Th, 228Ra, 137Cs and 40K in tea using gamma-spectrometry

The aim of the present work was to determine the concentration of radionuclides in all kinds of tea available at the local Egyptian market. Radioactivity of the nuclides ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Th, ²³²Th, ²²⁶Ra, ¹³⁷Cs and ⁴⁰K were measured in tea by direct γ-ray spectrometry using HPGe detector and their mean values were 16.0±5.3, 3.1±0.7, 34.3±3.4, 3.4±1.2, 3.0±0.6, 3.1±0.8, 0.9±0.2 and 623±25 Bq·kg⁻¹, respectively.     

Accumulation of137Cs by mushrooms from Rogozno area of Poland over the period 1984–1988

The concentration of naturally occurring⁴⁰K and¹³⁷Cs from fallout were determined in various mushrooms as well as in a few samples of forest soil from the same region over the period of 1984–1988. The¹³⁷Cs content in mushrooms before the reactor accident at Chernobyl was generally below 500 Bq kg⁻¹ dry matter, except Paxillus involutus /2700 Bq kg⁻¹/. A remarkable increase of the¹³⁷Cs activity /up to ten times/ was observed in 1986. For almost all examined species this activity remained basically at the same level for the next two years. No correlation between⁴⁰K and¹³⁷Cs in mushrooms has been found.     

Concentration of natural radionuclides in and around Padubidri on the coastal Karnataka,India

The activity concentrations of natural radionuclides viz. ²³²Th, ²²⁶Ra and ⁴⁰K were measured in soil samples of Padubidri on the coastal Karnataka, the site for the proposed coal based thermal power station, using gamma-ray spectrometry to establish a baseline data on radioactivity levels in the environment of the region. The activity concentration of ²³²Th varies in the range of 38.5–115.5 Bq·kg⁻¹ with a mean value of 66.0 Bq·kg⁻¹, the activity concentration of ²²⁶Ra varies in the range 35.3–72.5 Bq·kg⁻¹ with a mean value of 53.5 Bq·kg⁻¹ and that of ⁴⁰K varies in the range of 307.5–550.9 Bq·kg⁻¹ with a mean value of 419.3 Bq·kg⁻¹. The radium equivalent activity varies in the range of 140.0–242.9 Bq·kg⁻¹ with a mean value of 180.2 Bq·kg⁻¹. The correlation between ²²⁶Ra and ⁴⁰K, ²³²Th and ⁴⁰K and ²²⁶Ra and ²³²Th was studied from the results of the concentration of these naturally occurring radionuclides. The calculated dose rates in air due to these naturally occurring radionuclides varies in the range of 66.0–110.0 nGy·h⁻¹ with a mean dose rate of 83.1 nGy·h⁻¹.