Concentrations Of Th Research Articles

Exploring the alteration of environmental radioactivity in terms of compositional elements of heavy minerals in an anthropogenically affected urban river: Radiological and ecological risks assessment

This study explored the alteration of naturally occurring radioactive materials (NORMs: 226Ra (≈238U), 232Th, 40K) in an anthropogenically disrupted urban river-basin (Turag, Bangladesh) in terms of constitutional substances (Sc, Ti, V, Fe, La, Ce, Sm, Eu, Tb, Dy, Ho, Yb, Lu, Hf, Ta, W, Th, U) of heavy-minerals. Average activity concentrations of 226Ra (≈238U), 232Th, and 40K were 41.5 ± 12.9, 72.1 ± 27.1, and 639 ± 100 Bqkg−1, respectively which were relatively higher compared to crustal origin. ∑REEs, Ta, W, Th, and U were ~2 times higher compared to crustal values with Ce and Eu-anomalies. APCS-MLR and PMF receptor models were used to determine the various anthropogenic and/or geogenic sources of NORMs and elements. Layer-wise variations of NORMs and elements were observed to trace the response of sedimentary processes towards the incoming pollution load. Presence of REEs indicates moderate degree of ecological risk to aquatic biota. However, carcinogenic risk (3.84 × 10−4 Sv−1) were significantly higher than threshold limit.

Radiometric and petrographic characterization of El-Yatima granite: Evaluating radiological risks and mineralogical features

The current investigation aims to assess the potential of El-Yatima granitic pluton as a decorative stone by examining its natural radioactivity and mineralogical elements. Specifically, the study aims to determine the concentrations of radionuclides 40K, 232Th, and 226Ra, perform petrographic analyses, and evaluate the associated radiological risks to determine the safety and usability of the granite in construction and decoration, as well as to assess the potential of these granitic rocks as a safe and effective decorative stone for various applications. It has a 12 km2 surface area of 812 m above sea level. It is situated in the Eastern Central Desert. Its hypidiomorphic texture, medium-to-coarse grain size, and predominant composition of K-feldspars, quartz, and plagioclase are observed, along with minute amounts of muscovite and biotite. By employing NaI (Tl) gamma-ray spectroscopy, the natural radionuclide concentrations of 40K, 232Th, and 226Ra in El-Yatima granitic rocks were ascertained. Additionally, radiological concerns were identified for the materials that were examined. The average concentrations of radionuclides 40K, 232Th, and 226Ra are 178 Bqkg−1, 44 Bqkg−1, and 41 Bqkg−1, respectively. The following are the computed values: 117 Bqkg−1, 0.43, 0.32, 53 nGyh−1, average radium equivalent (Raeq), hazard indices (Hin and Hex) and dose rate (D), respectively. When compared to levels typically indicated, it was discovered that its values were within the worldwide standard. The study's findings could be a starting point for radiometric data for upcoming surveillance and epidemiological research.

Assessment of the level and risk of radioactive hazards in coastal sediments in northern Vietnam

ABSTRACT Radioactivity in coastal sediments in northern Vietnam was examined using data from five sediment cores to assess radioactivity concentrations and radiation risk indices. Radiation risk indices included radium equivalent activity (Raeq), the absorbed dose rate (ADR), the annual effective dose equivalent (AEDE), the activity utilization index (AUI), the external hazard index (Hex), the representative level gamma index (Iγr), and the annual gonadal effective dose rate (AGDE). The radioactivity concentrations of 40K, 232Th, 226Ra, 238U, and 137Cs were 567, 56.1, 35.1, 37.9, and 1.18 Bq/kg, respectively. The average concentrations of 40K, 232Th, 226Ra, and 238U were above the global average at five sites, except for 137Cs, which was low. The Raeq, Hex, and AUI indices were below the recommended values, while the AEDE, ADR, AGDE, and Iγr indices were above the recommended values. Moreover, 40K, 232Th, 226Ra, and 238U had significant impacts on the radiation hazard indices Raeq, ADR, AEDE, Iγr, AUI, Hex, and AGDE. There are three coastal sediment groups on the northern coast of Vietnam: Group 1 has a higher radioactivity and radiation risk index than Group 2 but a lower value than Group 3. Group 3 had the highest radioactivity and radiation risk index. The values of 40K, 232Th, 226Ra, and 238U and the ADR, AUI, Iγr, and AGDE indices in the sediment threaten the living environment.

Adsorption rate of uranium and thorium isotopes in soil and plants grown in a high background radiation area

ABSTRACT An important method for measuring radionuclide activity is alpha spectrometry. Ten soil samples were collected from the studied area. The activity concentrations of 238U and 234U in the collected soil samples ranged between 135 and 218 Bq kg–1 and between 117 and 183 Bq kg–1, respectively. 232Th, 230Th and 228Th activity concentrations ranged between 101 and 339, between 122 and 234 and between 106 and 385 Bq kg–1, respectively. When calculating the amount of radionuclide transport across the food chain, assessment models usually employ a transfer factor. Through root uptake, U and Th are transferred from the soil to food plants. To monitor the movement of radionuclides from the uranium series in diverse environments, it may be possible to use the ratios of uranium and thorium isotopes. Uranium mobility in soil depends on different physicochemical, organic and enzymatic factors and mechanisms. The high mobility of uranium is the main reason for the accumulation of uranium in the soil at root level and the possibility of its transfer to plants. A group of plants were selected that are grown in this area and the population relies on them mainly to meet their food needs. The concentration and transfer factor values of uranium isotopes were the highest in roots as compared with leaves and stems. Uranium in plants accumulates in roots and is then transferred to leaves. The mobility of uranium in plant tissues is constrained because it frequently adsorbs cell wall components. As a result, concentrations are frequently higher in tissues located in lower parts of the plant, with root surfaces having the highest concentrations.

Radioactivity concentration of natural and anthropogenic radionuclides in the soil of Banswara region, Rajasthan and associated radiation index parameters

Abstract Activity concentrations of gamma-emitting naturally occurring radionuclides (NORM’s) of 226Ra, 232Th, and 40K along with anthropogenic radionuclides of 137Cs in soil samples collected around the new upcoming nuclear power plant site at Banswara district, of Rajasthan, India were estimated. The mean radioactivity concentrations of 226Ra, 232Th, 40K, and 137Cs in surface soil samples of Banswara region were 17.6, 36.4, 309.7, and 1.4 Bq.kg−1, respectively. The mean activity of 226Ra, 232Th, and 40K is lower when compared to the world average values. Average radium equivalent activity (Raeq), absorbed gamma dose rates in air (DR), and annual effective dose (AED) for the soil of the study area are calculated as 94.0 Bq.kg−1, 43.0 nGy.h−1, and 0.26 mSv.y−1, respectively. Estimated AED to the general public is 0.24 mSv.y−1, which is comparable to the global values due to terrestrial radiation. These radiological index parameters were compared with internationally approved values and the recommended safety limits. The study and analysis of collected soil samples from the Banswara region of Rajasthan indicate that the soil of this area does not pose any significant radiological health hazard to the people residing in adjacent areas. Multivariate Statistical analysis of Pearson correlation and analysis of variance (ANOVA) has been carried out. The result of ANOVA test indicated that there is no remarkable difference in the total variance of radioactivity of NORMs with respect to distance and it also indicated that the soil of the area belongs to a similar lithologic origin. The Pearson correlation of 226Ra with 232Th (r = 0.53) and 40K (r = 0.68) showed a fairly positive correlation, suggesting that their content in soil samples were mostly influenced and controlled by sources of similar origin. Spatial distribution maps using the kriging interpolation algorithm have been generated for the 30 km × 30 km area.

Electrosorption-driven selective thorium removal from radioactive wastewater with phosphate – Incorporated g-C3N4 electrode

This research introduces a novel approach for developing an improved method for removing thorium ions (Th(IV)), termed as electrosorption, by fusing the principles of electricity and adsorption. The methodology involves utilizing a phosphate – incorporated graphitic carbon nitride (g-C3N4/P) electrode, synthesized via a hydrothermal – calcination process with urea as a precursor and bis (2-ethylhexyl) phosphoric acid (D2EHPA) as a dopant. Static batch experiments were conducted to explore the influence of various parameters, including voltages, initial Th(IV) concentrations and operational time, on the electrosorption of Th(IV). Characterization analysis including XRD, FT-IR, FESEM-EDS and XPS were conducted to validate the successful integration of phosphate into the g-C3N4 structure. The g-C3N4/P electrode demonstrated impressive adsorption capacity for Th(IV) electrosorption in an aqueous solution containing an initial concentration of Th(IV) at 100 mg.L−1. It was observed that applying a potential as low as −0.2 V resulted in significantly increase in the Th(IV) removal with 92.23 % (> 300 mg.g−1) within 30 minutes of duration, compared to cases without the electrochemical assistance (65.41 mg.g−1). Through FT-IR and XPS analyses, the adsorption mechanism was clarified as follows: (1) the negatively charged g-C3N4/P electrode attracted Th(IV) ions through electrostatic interaction; and (2) Th(IV) ions was coordinated with exposed oxygen (O), nitrogen (N) and phosphorus (P) atoms via complexation. In the context of real wastewater scenarios involving rare earth residue, encompassing Ce(III), La(III), Nd(III) and Pr(III) ions, the g-C3N4/P electrode showcased good capabilities in selectively adsorbing Th(IV). Additionally, the electrode synthesized in this study displayed considerable regenerative capabilities, sustaining a commendable removal ratio of approximately 70 % over five successive cycles. These findings underscore the promising potential of g-C3N4/P electrode for thorium removal through electrosorption applications.

Determination of Natural Radioactivity Levels and Radiation Hazards from the Soil of Tin Mining in Kyerwa District, Tanzania

Gamma spectrometry was used to determine the activity concentrations of the natural radionuclides 226Ra, 232Th, and 40K in soil samples from the Tin mining in Kyerwa District, Tanzania. The study findings revealed that the mean activity concentrations of 226Ra, 232Th, and 40K were 90.68, 65.45, and 630.95 Bq/kg, respectively. These values were all greater than the average global activity concentrations for 226Ra, 232Th, and 40K which are 32 Bq/kg, 45 Bq/kg, and 420 Bq/kg, respectively. Assessments of the radiological risks associated with these naturally occurring radionuclides were done. In this case, the radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and radioactivity level index (Iγ) were calculated. The results show that the mean values of Raeq, Hex, Hin, and Iγ were 230.6 Bq/kg, 0.628, 0.861, and 0.831, respectively. These results were below the global criteria levels for Raeq, Hex, Hin, and Iγ, which are 370 Bq/kg, 1, 1, and 2, respectively. Estimates for the absorbed dose rate in the air (DR), the annual effective dose equivalent (AEDE), and the annual gonadal equivalent dose (AGED) were also made. The findings revealed that the corresponding mean values for DR, AEDE, and AGED were 106.8 nGy/h, 1.07 mSv/y, and 744.4 μSvy-1. The mean values exceeded the global average value of 57 nGy/h for DR, 0.07 mSv/y for AEDE, and 2984 Sv/y for AGED. Therefore, Tin mining activities in the Kyerwa District could endanger the mining community from natural radioactive sources. In this study, therefore, we recommend performing a periodic inspection of the mining areas, monitoring the mining workers, and determining the level of activity and concentrations of different radionuclides in the mining area.

Assessment of natural and artificial radioactivity concentrations in infant powdered milk consumed in Albania and estimation of the annual effective dose

This study evaluates the radiological risk associated with the consumption of infant powdered milk in Albania. Infant powdered milk is the basic foodstuff for their growth and development in many countries around the world. The activity concentration of radionuclides (40K, 226Ra, 232Th and 137Cs) was measured in fourteen types by using the gamma-ray technique. The results indicated that the activity concentration of 40K, 226Ra and 232Th were detected in all selected samples, whereas 137Cs were not detected in most of them. The activity concentration of 40K, 226Ra and 232Th varies from 92.83 ± 4.32 to 400.53 ± 17.00 Bq kg−1, 0.80 ± 0.15 to 4.91 ± 0.28 Bq kg−1 and 0.19 ± 0.02 to 1.89 ± 0.14 Bq kg−1, respectively. The highest value for 137Cs was found to be 0.36 ± 0.03 Bq kg−1. The average values of Annual Effective Dose (AED) due to consumption of powdered milk were found to be 664.54 ± 31.11 μSv y−1 for infants ≤1 year and 138.53 ± 5.40 μSv y−1 for infants 1–2 years. The values of dose in this study were lower than the recommended limit of 1 mSv y−1 set by WHO/FAO and ICRP for all ages. Therefore, brands of powdered milk are safe, so, these can be normally consumed by infants in Albania.

Natural radioactivity in food crops and soil and estimation of the concomitant dose from tin mining areas in Nigeria

Mining of mineral ore is considered one of the anthropogenic sources of elevating the activity concentrations of the natural radionuclides in the environment, which in turn causes an increased risk of human exposure via the food chain. In an attempt to evaluate the radiological burdens resulting from tin mining activities in Nigeria, farm soil and sixty-two samples of different food crops grown around tin mining areas were evaluated for the activity concentrations of 226Ra, 232Th, and 40K using a high-purity germanium detector. The mean activity concentrations of 226Ra, 232Th and 40K in soil were 64.6 ± 29.5, 72.03 ± 28.73 and 680.6 ± 324.3 Bq/kg, respectively. These values were found to be higher than their corresponding world average values. However, the mean activity concentrations of the measured radionuclides in plants were below their respective world average values, as reported by UNSCEAR. The overall average annual ingestion dose due to the consumption of the analysed plants was 151 µSv/y, which is below the reported world average value of 290 µSv/y. The results obtained show that the hazard indices were low enough to cause any immediate radiological health complications due to the ingestion of the crops grown in the studied areas.

Radiation protection for Gabes phosphate area residents: Assessing natural radioactivity in soil and potable water samples

Phosphate mining activities are recognized to be one of various industrial processes generating enhanced Naturally Occurring Radioactive Materials (NORM) by introducing natural radionuclides into the surrounding soils and water bodies, posing a risk to human health.This study was carried out to assess the level of natural radionuclides in soils and potable waters collected from the phosphate area of Gabes city, located in southeastern Tunisia, and to evaluate radiation protection measures by estimating radiological health hazard parameters. Gamma spectrometry system employing an HPGe detector was used in this study to assess 40K, 232Th and 226Ra activity concentration in soils. The average values were found to be 163.7, 14.5, and 7.7 Bq kg−1, respectively, which were lower than worldwide average values. The radiological hazard parameters assessed in this study were radium equivalent activity (Ra-eq), external hazard index (Hex), external gamma absorbed rate (GDR), external annual effective dose (Deff) and excess lifetime cancer risk (ELCR). The calculated average values of the above-mentioned parameters were of 41 Bq kg−1, 0.1, 20.2 nGy h−1, 24.8 μSv y−1 and 8.7 × 10−5 all of which were found to be below their permissible standards.For potable water samples, the activity concentrations of radium were analyzed using an HPGe detector and those of uranium were determined by alpha spectrometry. The average activity concentrations of uranium and radium isotopes in underground water samples were found to be higher than those obtained in tap water samples. For both types of water, the average values for all radionuclides were found to be below their respective reference limits.The annual ingestion effective doses were also estimated in this study. The estimated average values for infant and children for underground water samples were higher than the permissible limit of 100 μSv y−1 set by WHO. The 226Ra was the main contributor to the effective doses for different age categories, followed by 228Ra.

Health Impacts of Natural Background Radiation in High Air Pollution Area of Thailand.

Chiang Mai province of Thailand is known for having the highest natural background radiation in the country, as well as being recognized as one of the world's most polluted cities for air quality. This represents the major contributor to the development of lung cancer. This research aims to estimate the comprehensive dose of both internal and external exposure due to natural background radiation and related health perspectives in the highly polluted area of Chiang Mai. The average values of indoor radon and thoron concentrations in 99 houses over 6 months were 40.8 ± 22.6 and 17.8 ± 16.3 Bq/m3, respectively. These results exceed the worldwide value for indoor radon and thoron (40 and 10 Bq/m3), respectively. During burning season, the average values of indoor radon (56.7 ± 20 Bq/m3) and thoron (20.8 ± 20.4 Bq/m3) concentrations were higher than the world-wide averages. The radon concentration in drinking water (56 samples) varied from 0.1 to 91.9 Bq/L, with an average value of 9.1 ± 22.8 Bq/L. Most of the drinking water samples (87%) fell below the recommended maximum contamination limit of 11.1 Bq/L. The average values of natural radionuclide (226Ra, 232Th and 40K) in 48 soil samples were 47 ± 20.9, 77.9 ± 29.7 and 700.1 ± 233 Bq/kg, respectively. All values were higher than the worldwide average of 35, 30 and 400 Bq/kg, respectively. The average value of outdoor absorbed gamma dose rate (98 ± 32.5 nGy/h) exceeded the worldwide average of 59 nGy/h. Meanwhile, the average activity concentrations of 226Ra, 232Th and 40K in 25 plant food samples were 2.7 ± 0.1, 3.2 ± 1.6 and 1000.7 ± 1.9 Bq/kg, respectively. The 40K concentration was the most predominant in plant foods. The highest concentrations of 226Ra, 232Th and 40K were found in Chinese cabbage, celery and cilantro, respectively. The total annual effective dose for residents in the study area varied from 0.6 to 4.3 mSv, with an average value of 1.4 mSv. This indicates a significant long-term public health hazard due to natural background radiation and suggests a heightened radiation risk for the residents. The excess lifetime cancer risk value (5.4) associated with natural background radiation was found to be higher than the recommended value. Moreover, the number of lung cancer cases per year per million average of 25.2 per million persons per year was in the limit range 170-230 per million people. Overall, our results will be used for future decision making in the prevention of lung cancer risk associated with natural background radiation.

Radiological assessment of commonly food crops in Southwestern Nigeria

Natural radionuclides are present in food items at different levels and are influenced by factors like background radiation, climate, and agricultural practices. These radionuclides play a crucial role in humans' internal radiation exposure. Notably, radionuclides within the decay series 238U and 232Th as well as 40K are significant concerns in radiation protection due to their prevalence and potential health risks. The activity concentrations of radionuclides 238U, 232Th, and 40K in several food crops consumed within Lagos city in Nigeria were measured using gamma spectrometry. The concentrations of 238U, 232Th, and 40K ranged from 0.90 to 55.30, BDL (Below Detection Limit) to 161.60 and 10.30 to 1075.20 Bqkg−1, respectively. The average radionuclide activity concentrations are below the acceptable global level, or the worldwide average values set by the United Nations Scientific Committee on the Effects of Atomic Radiation in 2000 (UNSCEAR, 2000), which are 35, 30, and 400 Bqkg−1 for 238U, 232Th, and 40K, respectively. The study calculated the annual effective dose for individuals consuming the studied food items, and the annual internal dose from ingesting was found to be 8.95 × 10–04 μSvy−1. It’s noteworthy that this computed value is below the worldwide value of 0.32 mSv y−1 set for the public. Additionally, the excess lifetime cancer risk (ELCR) value was 3.13 × 10−3 μSvy−1, which is within the world safe limit value (2.9 × 10−4 μSvy−1). Therefore, there is no potential radiological risk associated with the measured data.

Radiological, environmental, and structural investigations of Wadi El Markh granitic rocks, southeastern desert, Egypt

The radiological and environmental hazards of Wadi El Markh granitic rocks were investigated, and magnetic data were used to delineate the structural framework and determine the bedrock depth in the area. The result displayed that geological structures influence the occurrence of uranium mineralization in this area and are mainly associated with altered granitic formations. The activity concentrations of radioisotopes in the regions studied showed a range of values: 238U varied between 345 and 1729 Bq.kg−1, averaging 980 Bq.kg−1; 232Th ranged from 73 to 162 Bq.kg−1, with an average of 120 Bq.kg−1; and 40K varied from 829 to 1790 Bq.kg−1, average 1245 Bq.kg−1. The measured concentrations of 238U, 232Th, and 40K in the analyzed granitic rocks samples exceeded the worldwide average of 35, 45, and 412 Bq.kg−1, respectively. The primary radiological risks related to these granitic rocks were associated with the gamma radiation emitted by the radioactive elements. The statistical assessment confirmed that the main contributors to the radiological risks were uranium, potassium, and associated minerals in the granitic rocks. The entire investigation region has been determined to exceed the permissible safe radiation dose rate limit of 1 mSv/year. As a result, the study determined that the granitic rocks in the surveyed area were deemed unsuitable for construction because of their elevated levels of radioactivity. The effects of pollution on the ecological system were evaluated using several ecological indices, including the Geoaccumulation index (Igeo), Contamination factor (CF), Degree of Contamination (Cd), Pollution Load Index (PLI), Potential ecological risk factor (Eri), and Potential Ecological Risk Index (RI). Based on Cd and PLI, 100 % of the samples were found to be very highly polluted to the ecological system and suggest deterioration if used. Regarding RI, the metals were arranged as Cd > As > Co > Cu > Pb > Cr > V > Zn, with considerable risk in all samples.

An alternative approach to efficiency tracking in thorium determination in fertilizers by alpha spectrometry

Fertilizers play a key role in increasing crop yield per unit land answering the growing demand for food production. However, excessive or improper use of fertilizers can lead to several environmental issues including soil contamination. One of the known contaminants attributed to fertilizers are radionuclides. The goal of this study was to determine the concentration of thorium isotopes in several types of commonly used fertilizers produced in Poland. The methodology included the use of an alternative tracer (namely 228Th) to evaluate chemical recovery. The correctness of the proposed method was confirmed by analyzing certified reference materials. The obtained results showed that the activity concentration of 232Th was ranged from <0.34 Bq kg−1 for nitrogenous fertilizer up to 97 ± 22 Bq kg−1 for pure phosphate fertilizer.

Evaluating trends in groundwater quality of coastal alluvial aquifers of Eastern India for sustainable groundwater management.

Groundwater is a precious natural element which ensures global water, food, and environmental security in the twenty-first century. Systematic monitoring, sustainable utilization, preservation and remediation are critical aspects of efficient groundwater resource management. This study deals with the analysis of spatial variability and trend in groundwater chemistry as well as identification of possible contamination sources in a coastal alluvial basin of eastern India. Pre-monsoon season data of 14 groundwater-quality variables measured in 'leaky confined' and 'confined' aquifers were analyzed for ten years (2012-2021). Mann-Kendall (M-K) test with the Sen's Slope Estimator, Spearman Rank Order Correlation (SROC) and Innovative Trend Analysis (ITA) tests were employed to assess decadal (2012-2021) trends. The analysis of the results indicated that the 'critical' water-quality parameters exceeding the acceptable limits for drinking are TDS, EC, TH, pH, Mg2+, Na+, K+, Fe2+, HCO3-, Cl- and NO3-. Weak negative correlations between rainfall and groundwater elevation for both the aquifers reveal poor rainfall recharge into the aquifers. Therefore, a reduction in groundwater abstraction and augmentation of groundwater recharge is recommended. Trend analysis results indicated that the concentrations of TH, Mg2+ and Fe2+ exhibit significant increasing trends in the 'leaky confined aquifer'. In contrast, significant rising trends in TH, Mg2+, Na+, Fe2+, HCO3- and NO3- concentrations are identified in the 'confined aquifer'. Further, the SROC test could not detect the trends in groundwater quality in most blocks and for many parameters. On the other hand, the ITA test revealed significant trends in most of the parameters of the two aquifers in almost all the blocks. Trend magnitudes of the groundwater-quality parameters based on the Sen's Slope Estimator and the ITA test vary from -63.7 to 58.65mg/L/year for TDS, -14 to 39.07mg/L/year for TH, -1.49 to 4.83mg/L/year for Mg2+, -7.14 to 22.96mg/L/year for Na+, -0.32 to 0.44mg/L/year for Fe2+, -8.33 to 20.75mg/L/year for HCO3-, -26.52 to 31.01mg/L/year for Cl- and 1.29 to 3.76mg/L/year for NO3- over the study area. The results of M-K and ITA tests were found in agreement in all the blocks for both the aquifers. Groundwater contamination in both the aquifers can be attributed to weathering, geogenic processes, mineral dissolution, seawater intrusion, poor recharge pattern and injudicious anthropogenic activities. It is strongly recommended that concerned authorities urgently formulate efficient strategies for managing groundwater quality in the 'leaky confined' and 'confined' aquifers which serve as vital sources of drinking and irrigationwater suppliesin the study area.

Measurement of Natural Radioactivity in Fly Ash from a Lignite-Fired Thermal Power Plant and Radiological Risk Assessment Using RESRAD Code

In this study, the activity concentrations of natural primordial radionuclides in fly ash (FA) samples collected from the landfill area of Afşin-Elbistan A lignite-fired thermal power plant (AE-A LFTPP) located in Kahramanmaraş province of Türkiye were measured using a gamma-ray spectrometer. Also, the radiological risk was assessed using the Residual Radioactivity Onsite 7.2 code. The average activity concentrations of 226Ra, 232Th and 40K in FA samples varied from 291 ± 10 to 853 ± 25 Bq/kg, 23 ± 1 to 125 ± 4 Bq/kg and 112 ± 10 to 315 ± 18 Bq/kg, respectively. The predicted maximum total annual effective dose rate due to the natural radionuclides and their progenies is 4.7, 4.4, and 4.0 mSv/y at t = 1000 y for 0.5-m, 1.25-m, and 2.0-m cover scenarios, respectively. While the predicted maximum total cancer risk is 4.56 × 10−3 (3.95 × 10−3 for 226Ra, 5.18 × 10−4 for 232Th and 6.14 × 10−15 for 40K), 4.00 × 10−3(3.80 × 10−3 for 226Ra, 1.90 × 10−4 for 232Th and 7.69 × 10−15 for 40K) and 3.71 × 10−3 (3.71 × 10−3 for 226Ra, 1.820 × 10−8 for 232Th and 7.66 × 10−15 for 40K) at t = 1000 y for 0.5-m, 1.25-m and 2.0-m cover scenario, respectively. Results also revealed that the total doses and cancer risks are less in thicker cover scenarios throughout the 1000 y time span and that 226Ra is the major contributor to the risk in all the scenarios owing to its higher activity concentration than 232Th and 40K.

Assessment of natural radioactivity in the RCC building materials used in the valley region of Manipur, India.

An assessment of radioactivity concentration of reinforced cement concrete types of house was conducted in the valley region of Manipur, India. The average radioactivity concentration of 226Ra, 232Th, and 40K of portland cements are 39 (range: 32-52) Bqkg-1, 36 (range: 22-62) Bqkg-1, and 1812 (1254-2424) Bqkg-1; for concrete are 36 (range: 26-45) Bqkg-1, 65 (range: 45-86) Bqkg-1, and 660 (639-681) Bqkg-1; for sand are 45 (30-61) Bqkg-1, 114 (range: 55-212) Bqkg-1, and 1859 (range: 1413-2232) Bqkg-1; and for bricks are 30 (range: 24-37) Bqkg-1, 148 (range:79-184) Bqkg-1, and 1444 (range: 1093-2103) Bqkg-1, respectively. The annual effective dose was observed with an average value of 1.9 (range: 0.9-3.3) mSvy-1. However, gamma index was observed with an average value of 1.1 (range: 0.5-2.0).

The effect of extracellular polymeric substances on MICP solidifying rare earth slags and stabilizing Th and U.

Microbially induced carbonate precipitation (MICP) has been used to cure rare earth slags (RES) containing radionuclides (e.g. Th and U) and heavy metals with favorable results. However, the role of microbial extracellular polymeric substances (EPS) in MICP curing RES remains unclear. In this study, the EPS of Lysinibacillus sphaericus K-1 was extracted for the experiments of adsorption, inducing calcium carbonate (CaCO3) precipitation and curing of RES. The role of EPS in in MICP curing RES and stabilizing radionuclides and heavy metals was analyzed by evaluating the concentration and morphological distribution of radionuclides and heavy metals, and the compressive strength of the cured body. The results indicate that the adsorption efficiencies of EPS for Th (IV), U (VI), Cu2+, Pb2+, Zn2+, and Cd2+ were 44.83%, 45.83%, 53.7%, 61.3%, 42.1%, and 77.85%, respectively. The addition of EPS solution resulted in the formation of nanoscale spherical particles on the microorganism surface, which could act as an accumulating skeleton to facilitate the formation of CaCO3. After adding 20 mL of EPS solution during the curing process (Treat group), the maximum unconfined compressive strength (UCS) of the cured body reached 1.922 MPa, which was 12.13% higher than the CK group. The contents of exchangeable Th (IV) and U (VI) in the cured bodies of the Treat group decreased by 3.35% and 4.93%, respectively, compared with the CK group. Therefore, EPS enhances the effect of MICP curing RES and reduces the potential environmental problems that may be caused by radionuclides and heavy metals during the long-term sequestration of RES.

Zircon compositional systematics from Devonian oxidized I-type granitoids: examination of porphyry Cu fertility indices in the New Brunswick Appalachians, Canada

Zircon is a common, widely distributed accessory mineral in most igneous rocks and its refractory nature records magmatic evolution in terms of oxygen and U-Th-Pb isotopes, and trace-element contents all of which reflect the intrinsic physio-chemical evolution of the magmatic systems in which it crystallized. Zircon compositions can be used as an indicator of relative fertility of hypabyssal intrusions in terms Cu ± Mo ± Au porphyry mineralization. To further characterize syn- to post-collisional adakitic Devonian oxidized I-type granitoids in the New Brunswick (specifically, those with Cu ± Mo ± Au porphyry-style mineralization), LA-ICP-MS analyses (guided by µXRF-EDS mapping and SEM-BSE imaging of polished thin sections) of zircons from 13 granitoids was conducted. The zircons studied were similar in terms of their textures (homogenous cores, patchy zoning, oscillatory zoning, and some unzoned zircon); however, they have a wide range of trace- and minor-element (Hf, HREE, Y, Th, U) compositions. Specifically, Zr/Hf ranges between 24–60, whereas Th/U ranges between 0.15 and 5.37. The presence of inherited zircon affects the concentrations of Th and U, as well as other key elements. Estimated crystallization temperatures of granitoids, ranging from 737 to 899°C, were calculated via Ti-in-zircon geothermometry assuming reduced TiO2 and SiO2 activities. The calculated log fO2 values for zircons from some of these granitoids indicate a highly oxidized magmatic signature. Zr/Hf, Eu/Eu⁎, and (Eu/Eu⁎)/Y in zircon, as well as zircon (Ce/Nd)/Y are some of the best indicators of porphyry fertility. The Ce/Ce* in zircon exhibit a large range (1.1–590), with higher Ce/Ce* reflecting more metallogenically favourable oxidizing conditions. If Eu/Eu⁎ in zircon is ≥0.4 (relatively oxidized conditions), it indicates a high potential for an ore-forming porphyry Cu mineralizing system. Lower Eu contents reflect relatively reducing conditions, as Eu anomalies vary with oxygen fugacity as well, and the relative abundance of Eu2+ is higher, but does not substitute into the zircon lattice. The evidence extracted from analyzing the zircon composition within New Brunswick’s I-type granitoids indicates the fertility of these hypabyssal intrusions.

Investigation of radioactivity concentrations and soil-to-plant transfer factors in soil samples taken from different distance zones to the Metsamor nuclear power plant

Abstract Monitoring radioactivity around nuclear power plants is important to avoid the risks of radiation. This study provides an overview of the radioactive emission impact on the near surroundings of the Metsamor nuclear power plant in Armenia. In this context, 29 soil samples were collected from the 40, 80, 120, 160 km radius areas determined in the direction of Iğdır province by accepting the Metsamor nuclear power plant as the center. The activity concentrations of 226Ra, 232Th, 40K and 137Cs in soil samples ranged from 7.90 to 23.44, 7.11 to 33.55, 132.54 to 502.69 and 0.33 to 17.61 Bq/kg, respectively. In addition, the radioactivity concentrations in some agricultural products and the transfer factors from soil to plant were determined. As a result, there is no significant radiological risk in terms of studied radioisotopes for people living in this region.