Measurements of natural gamma radiation in beach sediments of north east coast of Tamilnadu, India by gamma ray spectrometry with multivariate statistical approach

Radiation risk assessment of quarry pit soil as construction material in Abeokuta, Nigeria: implications for environmental and public health

ABSTRACTEnvironmental and health risks posed by radionuclides in quarry pit soils are of great concern in environmental health monitoring. The current investigation was aimed at determining the natural radionuclide activity concentration (in Bq kg-1) of the understudied quarry pit granules used as construction materials. The collection and preparation of pit soil samples from Abeokuta quarry sites were done using standard methods, analysis of radiological parameters was carried out using hyperpure germanium (HPGe) spectrometer. Specific activity concentrations of 226Ra, 232Th, and 40K were measured. The values obtained were greater than the world weighted average of 35, 30, and 400 Bq kg-1 for 226Ra, 232Th, and 40K, respectively. The absorbed dose, the annual effective dose, and the radium equivalent were calculated and demonstrated significant values. The radionuclide content of the samples is relatively high and the use of pit soils as a building material, therefore, raises radiological concerns for dwellers in this area and requires periodic monitoring and undergoing a radiation protection program.

Evaluation of radioactivity in soil and rock samples from an undiscovered sea beach in the southeastern coastline of Bangladesh and associated health risk

This study marks the first-ever assessment of radiological hazards linked to the sands and rocks of Patuartek Sea Beach, situated along one of the world's longest sea beaches in Cox' Bazar of Bangladesh. Through the utilization of an HPGe detector, a comprehensive analysis of the activity concentrations of 226Ra, 232Th, and 40 K was conducted, and their activity ranged from 7 to 23 Bq/kg, 9-58 Bq/kg, and 172-340 Bq/kg, respectively, in soils, and 19-24 Bq/kg, 27-39 Bq/kg, and 340-410 Bq/kg, respectively, in rocks. Some sand samples exhibited elevated levels of 232Th, while the rock samples displayed higher levels of 40 K compared to the global average. The radiological hazard parameters were assessed, and no values surpassed the recommended limits set by several international organizations. Hence, the sands and rocks of Patuartek sea beach pose no significant radiological risk to the residents or tourists. The findings of this study provide crucial insights for the development of a radiological baseline map in the country, which is important due to the commissioning of the country's first nuclear power plant Rooppur Nuclear Power Plant. The data may also stimulate interest in the rare-earth minerals present in the area, which is important for the electronics industry, thorium-based nuclear fuel cycles.

Pollution status, health risk assessment of potentially toxic elements in soil and their uptake by gongronema latifolium in peri-urban of Ora-Eri, south-eastern Nigeria

Pollution monitoring of potentially toxic elements (PTEs) in a typical peri-urban area in Ora-Eri, Nigeria has been unchecked. Thus, unified evaluation process was developed to assess the pollution load index and potential health risk to inhabitants in mapped regions. The environmental risk was evaluated using contamination factor, geo-accumulation index and Nemerow integrated index. The source of heavy metal pollution was identified by Pearson correlation statistics. Public health risk caused by intake of leafy vegetables and soil exposure were estimated in regard to location of the farmland. The soil was non-contaminated by lead (Pb), arsenic (As), selenium (Se) and chromium (Cr) but gongronema latifolium was contaminated with As exceeding WHO/FAO limit. The bioaccumulation of PTEs in the vegetable follows this order: Se > Pb > As > Cr. The retention of selenium in leaf is high because is an essential metalloid. The pollution status of the studied locations ranged from low to moderate. Arsenic is the main contributor to the ecological contamination. The potential hazard health risk ranged from 5.37E-03 to 2.75E-02 for adults and 5.40E-02 to 2.60E-01 for children. The cancer risk for adults (2.43E-06 to 1.24E-05) and children (8.75E-05 to 1.15E-04) exceeded the acceptable standard (1 × 10-6) signifying gradual cancer effects. Therefore, the estimated hazard index and total cancer risk revealed that children are more prone to potential health risk than adults. Nevertheless, further continuous works should be carried out to monitor health risk in humans especially children and the control management policy of the peri-urban area should be adopted.

Assessment of a naturally occurring high background radiation area with elevated levels of thorium along coastal Odisha, India using radiometric methods

The present study evaluates the enrichment and distribution of radioelements along the eastern coast of India. India possesses the second largest reserve of thorium bearing monazite in the world, in terms of heavy minerals present primarily along its long coastline. Radioelement estimation of about 30 km long beach area along the eastern coast of India is reported and implications discussed. A total number of 822 data points were studied using a portable Geiger Muller counter, to estimate the variation of dose rates, due to the ambient radionuclides along two different trends. One was parallel (northeast-southwest) and the second one perpendicular to the coastline. Pre-selected samples from in-situ radiometric surveys on the heavy mineral placers were studied further, for quantitative estimation of the abundance of radioactive elements primarily uranium and thorium, using a High Purity Germanium detector. Radioelement concentration assessment of core samples (depth ~2 m), were studied from two different beaches. Radiological parameters like radium equivalent, annual effective doserate and absorbed dose rate has been calculated based on the ²³⁸U, ²³²Th and ⁴⁰K concentrations. Heavy mineral placers along the shoreline indicate a very high thorium (avg - 2990.22 Bq kg^-1) which is due to the extensive distribution indicative of monazite. The coastal area also exhibits relatively low uranium (avg - 319.1 Bq kg^-1). Based on its high thorium concentration, the area can be considered as a high natural background radiation area. Based on the concentrations of uranium and thorium, the weathering conditions and depositional environment prevalent along the beach areas have been discussed.

LEVELS OF NATURAL AND ANTHROPOGENIC RADIONUCLIDES IN SEDIMENTS OF SOME MOROCCAN COASTAL AREAS AND DOSE ASSESSMENT BASED ON ERICA TOOL

In this work, we considered the concentrations of natural and anthropogenic radionuclides (namely the 40K, 210Pb, 226Ra, 137Cs, 234Th, 228Th and 228Ra) in sediments from Moroccan coast areas by considering estuaries (Sebou and Loukkos) and marine ecosystems (M'diq Bay and three Lagoons: Moulay Bousselham, Sidi Moussa and Oualidia). Sediment samples were analyzed using Gamma spectrometry. The objective was to establish radioactivity levels in Moroccan coastal areas as well as radiological risk assessment by using the ERICA tool. The software allows the estimation of dose rates to biota (a set of reference organisms by default). The highest activity concentrations were found in sediment samples of Sidi Moussa Lagoon, possibly due to the anthropogenic activities, while the lowest levels were reported in Sebou estuary, attributed most probably to a flooding event that occurred in the same year of sampling. Also, 210Pb and 40K have the most significant concentrations, while 137Cs has the lowest concentrations with a great resemblance with similar works. The World Wide Average concentration of 226Ra was exceeded in the three lagoons and that of 40K only exceeded at Sidi Moussa Lagoon. The application of ERICA tool allowed the assessment of total dose rates that are mainly due to internal exposure with strong contribution of 226Ra mainly for phytoplankton in the case of marine ecosystems and insect larvae, mollusc-bivalve, mollusc-gastropod and zooplankton for estuary ecosystems. The total dose rates were far lesser than the admissible dose rate proposed by ERICA tool (10 μGy h-1) and, therefore, unlikely to cause harmful effects to organisms.

Gamma Ray Spectrometric Analysis of Sand Samples from Selected Beaches along Kenyan Coastline

In this study, the activity concentration levels of ²³⁸U, ²³²Th, and ⁴⁰K in sand samples collected from Shanzu, Nyali, Kenyatta, Tiwi, Shelly, and Diani beaches selected along the Kenyan coastline were determined using a gamma ray spectrometer with a NaI(Tl) detector. The average activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K in sand samples were analyzed as 87 ± 4, 98 ± 4, and 1254 ± 62 Bq/kg, respectively. Also, radium equivalent (Ra_eq) activity and internal (H_in) and external (H_ex) hazard index were calculated to assess the radiological hazards associated with the use of sand samples as building materials. The average values of Ra_eq, H_in, and H_ex were found as 327 ± 16 Bq/kg, 0.98, and 0.72, respectively. The average values of outdoor and indoor annual effective dose rates were estimated as of 0.23 and 0.63 mSv/y, respectively, which are below maximum recommended limit of 1 mSv/y. Generally, these results indicate no significant radiological health hazards for the studied beaches.

CHARACTERIZATION OF SAND SAMPLES FROM KARACHI BEACHES USING GAMMA SPECTROMETRY AND XRD

Chemical phase and distribution of natural radionuclides (226Ra, 232Th and 40K) were determined for sand samples collected from ten different beaches of Karachi. All samples, except one, were identified with major and minor phases as SiO2 and CaCO3, respectively. The average activity concentrations were 24.9, 25.0 and 239 Bq kg-1 for 226Ra, 232Th and 40K, respectively. Including all samples, the average radium equivalent activity was 79.1 Bq kg-1. The external and internal radiation hazard indices and representative level index were all found below unity. The average air absorbed dose rate at 1 m above the sand due to the natural radionuclides was 18.3 nGy h-1, which was less than the world average for soil. The corresponding annual effective dose rate was 22.4 μSv y-1. It was found that Raeq had positive significant correlation with the amount of quartz present at the beaches.

A study of daily variations of the outdoor background radiation measured in continuous mode in Federation of Bosnia and Herzegovina

Systematic monitoring of environmental radionuclides with the aim of early warning in emergency situations in Federation of Bosnia and Herzegovina (FB&H) was established in 2004. Environmental radiation monitoring network includes six automatic monitoring stations over the FB&H territory. This paper deals with the first study of ambient dose equivalent rates collected over the period of 2012-2017 with the main objective to investigate the temporal and spatial variations in the outdoor background radiation. The correlation analysis between the continuously acquired gamma dose rates and the simultaneous meteorological records on a daily basis contributed to a better interpretation of daily variations of the measured data. Derivation of the net ambient dose equivalent rates and the terrestrial radiation component from routine monitoring data was carried out as a prerequisite for adequate monitoring of background radiation. In addition, the terrestrial background component was estimated from the soil radionuclides at the same monitoring sites. The correlation analysis in a form of bivariation statistics between activity concentration of each pair of primordial radionuclides in the soil samples show that primordial radionuclides are not uniformly distributed over the FB&H territory. The mean values with the combined standard uncertainties for the terrestrial component evaluated from the soil radionuclides of (74.4 ± 12.5) nSv/h and from routine monitoring data of (81.8 ± 17.9) nSv/h are within the ranges reported for East and South European countries. The sources of statistical and systematic uncertainties were analyzed. The applied procedure of the terrestrial radiation component evaluation based on the daily monitoring data could be of complementary significance related to the existing evaluation procedures with a smaller sampling time of monitoring records. The results of the present study indicate that the acquired monitoring data are reliable enough to correctly assess the radiological situation in FB&H. In case of an emergency situation, the results obtained could be useful for a better identification of contaminated area.

A suggestion to radiological hazards characterization of 226Ra, 232Th, 40K and 137Cs: spatial distribution modelling

Spatial distribution modelling has been proposed to characterize the radiological hazards associated with concentration of natural ²²⁶Ra, ²³²Th, ⁴⁰K and artificial ¹³⁷Cs radionuclides in the nature. These elements have been determined for the sediment samples of the Bafa Lake with the aim of radiation hazard evaluation via a high purity germanium detector gamma spectrometry. Their activity concentrations in sediments are in the ranges of 29.87 ± 2.2-72.56 ± 11 Bq kg^{- 1} dry weight (dw), 31.57 ± 3.5-66.48 ± 8.3 Bq kg^{- 1} (dw), 332.01 ± 12-1092.37 ± 21 and 0.65 ± 0.04-3.96 ± 0.78 Bq kg^{- 1} (dw), respectively. In order to determine the radiological hazard associated with the radioactivity in the samples, the external terrestrial gamma dose rate in air, annual effective dose rate, the radium equivalent activity and the external hazard index are calculated and compared with the data from literature. Moreover, the spatial modelling distributions are obtained visually for radiological hazards characterization of these elements, which are very dangerous in terms of radiological and environmental pollution in the nature. These visual distributions give meaningful information for future researches on the migration of radionuclides in the environment.

Radioactivity levels and health risks due to radionuclides in the soil and sediment of mid-Black Sea: Kızılırmak Deltas-Turkey

Artificial and natural radionuclide pollutants of the marine environment have been recognized as a serious environmental concern. In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil and sediment samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI (Tl) detector. The average specific of activity concentrations for 238U, 232Th and 40K were found to be 28.59, 17.48 and 150.59 Bq kg−1, respectively. On the other hand, 137Cs was also measured in some samples. 137Cs (t1/2=30.17 years) is a man-made radionuclide released from nuclear fission and activation processes. It has a mean value of 5.32 Bq kg−1. From the activity concentrations, the radium equivalent activity (Raeq), the absorbed gamma dose rates (DR), the annual gonadal dose equivalent, annual effective dose equivalent, internal (Hin), external hazard index (Hex) and excess lifetime cancer risk were estimated. This study can be used as a base line for future investigations and the data obtained in this study may be useful for natural radioactivity mapping and also be used as a reference data for monitoring possible radioactivity pollutions in future.

A REVIEW ON VARIATION OF NATURAL RADIOACTIVITY ALONG THE SOUTHEAST COAST OF TAMIL NADU FOR THE PAST 4 DECADES (1974-2016)

This review deals with natural radioactivity variation along the southeast coast of Tamil Nadu for the past four decades (1974-2016). About 40 research works have been conducted along the coast since 1974 in various environmental matrices using a variety of experimental methods. For these measurements researchers are adopted different experimental methods. The measured gamma dose rate ranged from 30 to 8700 nGy/h. The mean specific activity of 238U, 232Th and 40K was found to be 58.8 ± 28.7, 465.2 ± 147.3 and 311.2 ± 27.8 Bq/kg, respectively. The calculated annual exposure rate ranged from 0.29 to 12.8 mSv/y with the mean value of 3.7 mSv/y which is above the global average of 2.4 mSv/y as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) (Report to General Assembly, Annex B Exposures of the public and workers from various sources of radiation. United Nations, New York (2008)). Plant food items recorded low 210Po activities as compared to seafood organisms. Grain size, season and place of sampling have a decisive bearing on coastal radioactivity. Therefore, it is concluded from the review data that there is an appreciable elevation in background radiation level in the coastal region. This review suggests that new radiological surveys using improved methodology that cover the entire coastal stretch are needed.

Assessment of natural radioactivity and gamma-ray dose in monazite rich black Sand Beach of Penang Island, Malaysia

Activity concentrations of primordial radionuclides in sand samples collected from the coastal beaches surrounding Penang Island have been measured using conventional γ-ray spectrometry, while in-situ γ-ray doses have been measured through use of a portable radiation survey meter. The mean activity concentrations for ²²⁶Ra, ²³²Th and ⁴⁰K at different locations were found to be less than the world average values, while the Miami Bay values for ²²⁶Ra and ²³²Th were found to be greater, at 1023±47 and 2086±96Bqkg^{̶ 1} respectively. The main contributor to radionuclide enrichment in Miami Bay is the presence of monazite-rich black sands. The measured data were compared against literature values and also recommended limits set by the relevant international bodies. With the exception of Miami Bay, considered an elevated background radiation area that would benefit from regular monitoring, Penang island beach sands typically pose no significant radiological risk to the local populace and tourists visiting the leisure beaches.

Natural radioactivity level in beach sand along the coast of Xiamen Island, China

The activity concentration of (40)K, (232)Th and (226)Ra was determined in beach sand samples collected from Xiamen Island, China using gamma ray spectrometry. The activity concentrations of (40)K, (232)Th and (226)Ra in the beach sand range from 197.4 to 487.6, 6.5 to 41.4 and 7.9 to 25.7 Bq kg(-1) with the mean of 401.0, 11.3 and 14.1 Bq kg(-1), respectively, which are lower than the averages of Chinese soil and world soil. The radium equivalent activity values in all beach sand samples are lower than the recommended limit of 370 Bq kg(-1). The external hazard index values are less than unity. The outdoor air absorbed dose rate and the corresponding annual effective dose rate of beach sand investigated are lower than the worldwide average.