Isotopes in Environmental and Health Studies最新文献

This study presents an investigation into the natural radioactivity levels of ²³⁸U, ²³²Th, and ⁴⁰K using a thallium-doped sodium iodide (NaI(TI)) detector and associated radiological hazards in river sediments, specifically sand, which serves as a crucial building material in the KwaZulu-Natal Province of South Africa. The assessment aims to provide insights into potential radiological risks posed by the utilization of these sediments in construction activities. The mean activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K are 145.33, 38.67, and 362.67 Bq kg^-1, 124.64, 60.60, and 353.00 Bq kg^-1, 144.00, 48.80, and 371.00 Bq kg^-1, 92.95, 52.00, and 368.75 Bq kg^-1, 133.55, 45.60, and 324.40 Bq kg^-1, and 109.50, 52.50, 381.50 Bq kg^-1 for Umngeni River, Umsunduzi River, Ashburton Sarupen, Hammersdale, Kwanjobekazi, and Cator Ridge, respectively. The obtained values of the radiological hazard indices (radium equivalent activity, external hazard index, internal hazard index, and activity utilization index) were below the world average values reported for building materials. Therefore, the studied samples are radiologically safe for use as building materials in the study area because they may not constitute any severe radiological hazards to residents.

Plant test systems are a sensitive way to detect the genetic effects of various contaminants in environmental compartments: water, soil and sediments. Biotesting of the genotoxicity of soil samples with various activity concentrations of naturally occurring (²²⁶Ra, ²³²Th, ⁴⁰K) and artificial (¹³⁷Cs) radionuclides in soil, from the territory of the Aragats Massif (Armenia) was carried out with the application of the Tradescantia micronucleus (Trad-MСN) and stamen hair mutation (Trad-SHM) bioassays of Tradescantia (clone 02) model test-object in the soil - plant system. Undisturbed soil sampling was performed in the southern slopes of the Aragats Massif, from different altitudes (from 1000 to 3200 m above sea level). The soils of the Aragats Massif exhibited a background level of naturally occurring materials (NORM) activity. The highest variability was indicated for ⁴⁰K. The activity concentration of ¹³⁷Cs in soils exhibited a naturally increased as the altitude increased. Tradescantia (clone 02) was grown on the undisturbed soils in the greenhouse. To determine the level of genotoxicity of the studied soil samples, the Tradescantia-based Trad-MCN and Trad-SHM tests were applied. The activity concentrations of NORM and artificial ¹³⁷Cs in soil and phytomass were determined using an HPGe detector-based gamma spectrometer (Canberra). Tradescantia (clone 02) accumulated mainly ⁴⁰K, accumulation of ²²⁶Ra observed in one soil sample. In the areas with elevated activity of NORM, levels of genotoxicity were significantly higher compared to the control soil sample with the low rate of spontaneous mutation frequency. The positive correlation between genetic damages of Tradescantia (MCN and SSH) and contents of ⁴⁰K and ²²⁶Ra in soils was revealed. The obtained results indicated the possibility of using Trad-MCN and Trad-SHM tests of Tradescantia (clone 02) for biotesting of background radioactivity in natural areas.

Stable H-O and radiogenic Sr isotopic compositions of bottled water in South Korea were investigated to trace water origins and to elucidate hydrogeochemical water-rock interactions within aquifers. Eighty-one bottled water samples were collected across the country. The δD and δ¹⁸O values, and ⁸⁷Sr/⁸⁶Sr ratios and Sr contents of groundwater-sourced bottled water samples were in the ranges of -68 to -40 ‰, -10 to -7 ‰, 0.7050-0.8112, and 14-400 μg L^-1, respectively. The corresponding ranges for desalinated deep-ocean water samples were -1.2 to 1.6 ‰, -0.35 to 0.10 ‰, 0.7078-0.7092, and 12-407 μg L^-1, respectively. Isotopic compositions indicate spatial variations in stable isotopic signatures with geographical location, while Sr isotopic ratios are correlated with the geological characteristics of water sources. Oxygen isotopic compositions of bottled water show a negative correlation with latitude, while Sr isotopic ratios vary with aquifer geology. The integration of stable and radiogenic isotopic compositions improves our understanding of water-rock interactions, enabling accurate authentication of water sources.

Understanding the stable hydrogen isotope (δ²H) composition and fractionation in lipid biomolecules of primary producers, such as terrestrial and aquatic plants, is crucial for deciphering past environmental conditions, as well as applying compound-specific stable isotope analysis for the study of metabolic and ecological processes. We conducted a new tracer experiment to explore the δ²H composition of algal fatty acid biomarkers, focusing on freshwater algae, which form the base of aquatic food webs. We selected a range of algal species widely found in freshwater ecosystems and cultivated them under controlled conditions. First, we added ²H₂O to ambient water as a tracer to investigate the net hydrogen isotope fractionation during algal lipid synthesis at isotopic equilibrium, which is particularly informative for paleo-geochemical studies. Then, we conducted kinetic experiments to quantify the time needed for algal fatty acids to achieve isotopic steady-state conditions in response to the change in ambient water δ²H values. Our findings revealed substantial variability in hydrogen isotope fractionation among different algal taxa and various fatty acids. Based on taxa, different fatty acids exhibited faster integration of water hydrogen than others, but they were not necessarily in the order of the biosynthetic pathway. This experiment underscores the complexity of hydrogen isotope fractionation and the requirement for controlled laboratory studies to properly apply compound-specific stable H isotope analysis techniques in ecological and paleo-environmental studies.

This study investigates the levels of natural and artificial radioactivity in rice samples collected from various local markets in Islamabad, Pakistan. The ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations were measured through gamma-ray spectrometry with a NaI(Tl) detector. The average activity concentrations were 1.67 ± 1.19 Bq kg^-1 for ²²⁶Ra, 3.31 ± 1.83 Bq kg^-1 for ²³²Th, and 88.51 ± 11.65 Bq kg^-1 for ⁴⁰K. Calculated radium equivalent (Ra_eq) values ranged from 7.35 to 18.08 Bq kg^-1, with a mean value of 11.11 Bq kg^-1, all below the permissible maximum of 370 Bq kg^-1. The absorbed dose rates ranged from 6.85 to 16.39 nGy h^-1, with an average of 10.64 nGy h^-1, falling below the acceptable limit of 51 nGy h^-1. The outdoor and indoor radiation hazard indices (H_ex and H_in) had mean values of 0.03, both below the threshold value of one. The external and internal hazard indices (I_γ and I_α) were both 0.088, also below the critical value of one. The excess lifetime cancer risk (ELCR) ranged from 0.28 to 0.11, with a mean value of 0.18, which is less than the critical value of one. Overall, the radioactivity levels in the analyzed rice samples are within the acceptable limits set by the International Commission on Radiological Protection and are below global averages. These results offer important insights into the radiological safety of rice consumption in the study area.

Copper, a malleable and ductile transition metal, possesses two stable isotopes. These copper isotopic composition data have recently found diverse applications in various fields and disciplines. In geology, copper isotopes serve as tracers that aid in investigating ore formation processes and the mechanisms of copper deposits Likewise, it has emerged as a valuable tracer in polluted environments. In plant biology, copper acts as an essential micronutrient crucial for photosynthesis, respiration, and growth. Copper isotopes contribute to understanding how plants uptake and dispense copper from the soil within their tissues. Similarly, in animals, copper serves as an essential trace element, playing a vital role in growth, white blood cell function, and enzyme activity. In humans, copper acts as an antioxidant, neutralising harmful free radicals within the body. It also helps in maintaining the nervous and immune system. Furthermore, copper isotopes find medical applications, particularly in cancer diagnostics, neurodegenerative diseases, and targeted radiotherapy. However, excessive copper can have detrimental effects in humans such as it can cause liver damage, nausea, and abdominal pain, whilst in plants it can affect the growth of plants, photosynthesis, and membrane permeability. This review emphasises the significance of copper and its isotopes in geology, the environment, and human health.

This study investigates the activity concentration of natural radionuclides in a diverse range of food samples in the Koya district markets food baskets, including both domestic and imported products. The samples cover annual crops (e.g. coffee, tea, kidney beans), tree nuts (e.g. almonds, pistachios), and other items (e.g. beef, fish, milk) by using a high-purity germanium (HPGe) detector. This research addresses a notable gap by providing baseline data on radionuclide concentrations and assessing potential health risks. Average activity concentrations for ²²⁶Ra, ²³²Th, and ⁴⁰K were 0.943, 0.367, and 191.8 Bq kg^-1, respectively. Radium equivalent activity values ranged from 2.88-58.48 Bq kg^-1, all below the safety limit. The average excess lifetime cancer risk (ELCR) was 0.154 mSv a^-1, indicating safety for most samples, though coffee and tea showed higher levels. This study provides new data crucial for future research and regulatory monitoring, underscoring the need for further investigation into geological impacts on radionuclide levels.

The stable isotope compositions of sulphur (δ³⁴S) and oxygen (δ¹⁸O) in barite are frequently used as proxies for microbial sulphate reduction (MSR) in diverse environments, such as in relation to anaerobic oxidation of methane in marine cold seeps. There, isotopically heavy barite is used as a marker for MSR from a sulphate pool that has undergone semi-closed system conditions. Closed-system MSR is also a commonly observed feature in igneous rock hosted fracture aquifers, as shown by extremely ³⁴S-enriched pyrite. What is less well-constrained is whether δ³⁴S in barite can be used as a proxy for MSR in such systems. Here we explore the microscale heterogeneity of δ³⁴S and δ¹⁸O via secondary ion mass spectrometry and the trace element Sr via LA-ICP-MS maps in barite precipitated in granite-hosted boreholes during a 17-year experiment, at Äspö, Sweden. We compare it with δ¹⁸O_sulfate, δ³⁴S_sulfate, and δ³⁴S_sulfide of the fracture fluids and with paragenetic pyrite with δ³⁴S values reflecting closed system MSR. The δ¹⁸O values in barite (+9.4 to +16.9 ‰) represent two generations of barite, one with low values and one with high values. The latter are likely impacted by sulphur disproportionating or -oxidizing bacteria. The barite reflects a much smaller span in δ³⁴S (+14.5 to +28.6 ‰) than the pyrite (-47.2 to +53.3 ‰). This lack of extremely high δ³⁴S_barite values is proposed to be due to that barite saturation only occurred in the early parts of the Rayleigh cycle. Additionally, fluid migration has affected the δ³⁴S values to lower values, accompanied by higher Sr concentrations. Taken together, barite δ³⁴S values cannot be regarded as a reliable independent proxy for MSR in deep sulphate-poor igneous rock hosted aquifers. However, the relation between the δ³⁴S values of coeval barite and pyrite is regarded as a useful proxy for MSR-related fractionation during early stages of MSR.