Isotopes in Environmental and Health Studies最新文献

This study investigates radon concentrations in groundwater from 20 locations in Iluagba, Kogi State, Nigeria, analyzed using a liquid scintillation counter. Radon levels ranged from 10.6-43.1 Bq/L (average 24.1 Bq/L). Although below the World Health Organisation (WHO) limit of 100 Bq/L, about 90 % exceeded the United States Environmental Protection Agency (USEPA) advisory level of 11.1 Bq/L, indicating potential long-term health risks. The annual effective dose (AED) was highest in infants (up to 163.5 µSv/y), with seven samples exceeding the WHO reference dose of 100 µSv/y. Excess lifetime cancer risk (ELCR) values for all age groups surpassed the USEPA safety threshold (1.0 × 10^-⁴), identifying infants as the most vulnerable group. Organ-specific analysis showed the lungs received substantially higher doses than the stomach, confirming inhalation as the primary exposure route. While strong correlations (r ≈ 1.0) validated internal data consistency, the elevated radiological risk remains the key concern. Compared with other Nigerian regions, Iluagba exhibits moderate to high exposure levels. These findings underscore the need for targeted radon mitigation, community education, and routine groundwater monitoring to safeguard public health in Kogi State.

This study aims to determine the specific activity of natural uranium isotopes, including uranium-238 (²³⁸U), uranium-234 (²³⁴U), and uranium-235 (²³⁵U), in soil and vegetable samples - specifically tomato, potato, onion, carrot, and radish - collected from the Tafila district, Jordan, and to assess the soil-to-plant transfer factors using alpha spectrometry with a passivated implanted planar silicon (PIPS) detector. A total of eight soil samples and eight corresponding vegetable samples were obtained from eight distinct locations. The results revealed considerable spatial variability in uranium activity concentrations, reflecting the influence of geological formations and environmental conditions. The average activity concentrations were 251.6 ± 14.2 Bq/kg for ²³⁸U, 10.5 ± 1.9 Bq/kg for ²³⁵U, and 248.8 ± 13.9 Bq/kg for ²³⁴U in soil samples, while vegetable samples showed lower concentrations of 3.2 ± 0.16, 0.21 ± 0.05, and 3.1 ± 0.17 Bq/kg for ²³⁸U, ²³⁵U, and ²³⁴U, respectively. The calculated transfer factors ranged from 4.4 ± 0.4 × 10^-3 to 29.1 ± 1.8 × 10^-3 for ²³⁸U, 6.4 ± 1.4 × 10^-3 to 33.0 ± 15.7 × 10^-3 for ²³⁵U, and 4.3 ± 0.4 × 10^-3 to 28.7 ± 1.9 × 10^-3 for ²³⁴U, which reflects notable differences in uranium uptake efficiency among the studied plant species. A strong correlation (R² = 0.99) was observed between ²³⁸U and ²³⁴U in both soil and vegetable samples, suggesting isotopic equilibrium through natural decay. These findings provide essential baseline data for future studies on uranium mobility, bioavailability, and potential radiological risks in agricultural systems within the Tafila District.

This paper reports concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in drinking waters from Islamabad, Pakistan. The aim is to estimate the radiological hazard risk and assess the radiation safety due to drinking water use. Radiation hazard indices and excess lifetime cancer risks are reported from all measurements. Different drinking water samples have been collected from Islamabad (33° 38'N, 73° 09'E) and analysed using a high purity germanium detector (HPGe). The average concentration values of ²²⁶Ra, ²³²Th and ⁴⁰K were 6 ± 0.6, 32 ± 1 and 74 ± 2 Bq L^-1, respectively. The radium equivalent activity was 58 Bq L^-1, the outdoor external dose was 0.2 nGy/h, the indoor external dose was 46 nGy/h and the total average annual dose was 0.2 nGy/h. The excess lifetime cancer risk was equal to 0.8 × 10^-3. All reported values are lower than the globally calculated values and within recommended limits.

This pioneering study investigates the levels of naturally occurring radioactive materials in soil collected from the vicinity of Srikail gas field, Bangladesh, utilizing a high purity germanium (HPGe) detector. Forty soil samples were systematically collected from concentric circles around the gas well, with approximate radii of 100, 200, 300, 400, and 500 m. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K ranged from 12-27, 24-45, and 255-480 Bq/kg, respectively, with most values aligning with global averages of 35, 35 and 400 Bq/kg respectively. Notably, two samples showed the presence of artificial radioactivity (¹³⁷Cs). All the radiological hazard indices are well within the recommended safety limits. However, this study emphasizes the need to establish baseline data for the soon-to-be-commissioned Rooppur Nuclear Power Plant and its nearby areas. It also highlights the importance of regular monitoring to detect any future changes in radioactivity levels that might come from natural processes or human activities.

We use Sr isotopes to increase the precision of DNA-based origin estimates of wildlife products. Population information is used to develop Sr isotope Elephant Polygons that are overlaid onto the region of origin identified by DNA assignment to determine the sources of seized ivory samples. Our approach is cognizant of isotope mixing due to isotope turnover within animals and also of the large home range of elephants or other mobile species. Genetic information from 3 different law enforcement ivory seizures suggests a region of origin confined to Kenya and Tanzania in eastern Africa. We determine characteristic ⁸⁷Sr/⁸⁶Sr ratios for each of 25 different Elephant Polygons within this region using analyses of more the 600 known-origin reference samples. Using both the ⁸⁷Sr/⁸⁶Sr ratios of the seized ivory samples and elephant population estimates from individual Elephant Polygons we find that at least 75 % of the samples likely came from a single Elephant Polygon which includes the Tsavo National Parks in Kenya and the Mkomazi National Park in Tanzania. A few samples may have come from other regions, most likely from Tanzania. This study illustrates the value of combining genetics, isotope geochemistry, and population surveys in wildlife forensics studies.

Microplastics are emerging environmental pollutants that are contaminating every sector of the biosphere due to their small size. Studies have shown that microplastics act as a potent vector for transferring hazardous contaminants into the soil fauna, terrestrial plants, and they can further seep into groundwater or nearby water bodies. Density separation is a conventional technique to remediate microplastics, but the salts used for remediation are quite expensive, and each has its own disadvantages. The current study focused on developing an environmentally benign flotation media whose disposal in the environment is safe after extracting microplastics and is cost-effective. Three cost-effective and easily available salts were tested and reported to include food-grade common salt, table sugar, and an equal volume of a common salt and table sugar solution. In all the tested solutions, the food-grade salt-sugar solution (1:1) was found to be efficient in separating microplastics with an efficiency equal to that of the most frequently used AR-grade sodium chloride solution. Sugar-salt solution was an effective density separation medium with a performance efficacy of 100 % for low-density microplastics and 43.3-76.7 % for high-density microplastics, when tested with spiked samples.

Tree rings can provide annual records of environmental and climatic conditions. These records can be obtained through the physical characteristics of tree rings or the isotopic composition of their structural elements. Oxygen isotope chronologies are created by objectively combining data from trees. The diachronic patterns observed in the δ¹⁸O of the tree-ring cellulose represent tree-environment interactions. The abundance of ¹⁸O in tree-ring cellulose is closely linked to hydroclimate, and is influenced by source water δ¹⁸O and atmospheric humidity. Long sequences of annually resolved tree-ring δ¹⁸O values have been used, to good effect, in the dating of archaeological timbers and as proxies in the reconstruction of climatic variables. In this research we have established a working methodology for producing and measuring δ¹⁸O in tree-ring α-cellulose at the University of Groningen. We have demonstrated an average precision of approximately 0.2 ‰ under a variety of conditions, which exceeds the expected performance of continuous flow IRMS techniques. Difficulties were encountered during the calibration of tree-ring cellulose δ¹⁸O determinations using non-cellulose, organic reference materials. A difference in pyrolysis behaviour or one, or more compromised materials, resulted in poor agreement between measured and expected δ¹⁸O values on cellulose standards. This opens the possibility for further study. Analysis of cellulose standards alongside water reference materials and an independent quality control standard proved successful, resulting in a number of cellulose standards being accurately placed on the VSMOW-SLAP scale, including the intercomparison and de facto reference material IAEA-C3 holocellulose.

Stable isotope analysis has become a valuable tool for reconstructing dietary patterns, but whole blood remains an underutilised matrix in these assessments. Therefore, this study investigates how δ¹³C and δ¹⁵N values in whole blood vary according to the frequency of consumption of different meat types in a Brazilian population and examines their associations with physiological and metabolic markers, including body mass index (BMI), cholesterol levels, and glutamic-oxaloacetic transaminase (GOT). Blood samples were collected from 287 individuals across 19 communities in Espírito Santo, Brazil, and analyzed for stable carbon and nitrogen isotope composition. Our findings indicate that higher beef, pork, and fish consumption was associated with enriched δ¹³C values, while both beef and fish consumption were associated with higher δ¹⁵N values. No significant isotopic differences were observed for chicken intake. δ¹³C values were positively associated with BMI and cholesterol levels in men but not in women, suggesting sex-specific metabolic influences on carbon isotopic fractionation. No significant associations were observed between δ¹⁵N and BMI or cholesterol levels, likely due to nitrogen turnover processes such as transamination and deamination. Additionally, a negative association between δ¹⁵N and GOT levels was identified, supporting the hypothesis that transamination may counteract nitrogen enrichment in blood, potentially limiting δ¹⁵N as a direct biomarker of protein intake. These results reinforce the applicability of stable isotope analysis for dietary assessment, demonstrating its potential to distinguish dietary patterns based on isotopic composition. They also highlight the influence of sex-specific metabolic processes on isotopic fractionation, underscoring the need for further research on nitrogen metabolism in dietary studies. This study provides novel insights into the role of stable isotopes in human nutrition and health research, contributing to the refinement of isotopic biomarkers for dietary and metabolic evaluations.

The natural tracers δ¹⁸O and δ²H are essential for tracing hydrological processes by identifying water sources, tracking evaporation loss and floodwater dynamics to enhance water management and flood mitigation strategies. This study employed this approach in the ephemeral, endorheic Cuvelai-Etosha Basin (CEB), spanning northern Namibia and southern Angola, to determine its viability in capturing spatial and temporal hydrological patterns, their timing and interactions during a medium flood condition (2017), and contrasted with a drought year (2014). During the 2017 wet season 219 grab surface water samples were collected from ephemeral waterbodies in four sampling campaigns (February, March, April and May) in addition to a single campaign in May 2014 (63 samples). Samples were analysed for stable isotopes (δ²H and δ¹⁸O) at the University of Namibia laboratory using an off-axis integrated cavity output spectroscope (Los Gatos, DLT-100). Results for 2017 revealed a compositional range of -13.51 to 12.44 ‰ for δ¹⁸O and from -100.1 to 50.9 ‰ for δ²H. The 2017 samples plot along a low sloping line (δ²H = 5.19 δ¹⁸O - 13.91) indicating the dominance of the evaporation effect. Amount, seasonality, and latitude effects were also identified in the isotopic composition of the iishana water. The surface water loss to evaporation is in the range of 24-42 % from March to April and 39-69 % from March to May. The d-excess decreased from April and remains relatively low in May, which supports observations of evaporation losses. The overall large water losses from the system via evaporation reduces the water availability substantially, and the impact is more pronounced in the western part of the basin than in the eastern. Since evaporative loss begins early, even during the rainy season, proactive technical solutions such as floodwater harvesting need to be planned accordingly to mitigate losses and optimizing water use.

The commencement of the Industrial Revolution has resulted in an unprecedented increase in the concentration of atmospheric CO₂ (pCO₂). It is, therefore, important to understand how plant communities respond to increased levels of CO₂ levels in the environment. To this end, we examined the effects of spatial variation in pCO₂ on plant physiology using carbon isotope ratios (δ¹³C values) and stomatal index (SI) in C₃ plant leaves along a transect from the central Ganga Plain to the foothills of the Himalayas with industrial and non-industrial zones. Our study shows that the plants adjacent to the industrial areas have much lower δ¹³C values (avg. -31.8 ‰) and absorbed more fossil fuel-derived carbon (ca. 18 %) than those growing in non-industrial areas (-28.3 ‰). We also observed ca. 25 % lower SI values from the industrial area, suggesting that the increase in CO₂ concentration (for a given water budget) led to high photosynthetic rates with low stomatal conductivity. Therefore, a long-term increase in pCO₂ would lead to higher water-use efficiency in C₃ plants, which would allow them to function better in low moisture conditions. We also suggest that the δ¹³C and SI values can be used for mapping carbon sequestration by plants growing in industrialized regions.