Isotopes in Environmental and Health Studies最新文献

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.

Precipitation stable-isotope data are often used in hydroclimatic, hydrological and hydrogeological investigations, with measurements typically undertaken on integrated monthly samples. However, daily sampling reveals overlooked aspects of controls on precipitation isotope values, including synoptic meteorological conditions. We present a one-year record of stable isotopes in daily precipitation during 2021, from a site in SE England close to Greater London. We find marked daily variability over the course of the year (-15.62 to +0.92 ‰ for δ¹⁸O, -108.7 to +2.9 ‰ for δ²H and -6.5 to +23.1 ‰ for deuterium excess). Correlations with individual meteorological variables including precipitation amount, temperature and weather type are moderate to weak suggesting complex controls on the daily rainfall isotope values. The daily data are compared with three other daily datasets from England and, by conversion to monthly values, directly with data from three long-term collection stations across Britain and Ireland. The scale of variability in the daily data from our site is consistent with that seen in other English records despite them all coming from different time periods. The monthly data show broad consistency, although there are differences that also highlight geographical variability in precipitation values across the British Isles.

Incorporation of soil amendments with high organic carbon content (HCA) can reduce losses of mineral nitrogen (N) from agricultural soils. The magnitude of N immobilization and remobilization is strongly controlled by the availability of carbon (C) and phosphorus (P). However, the exact mechanisms and interactions between C, N, and P availability are poorly understood. An eight-month incubation experiment was conducted on recultivated mine soil with low organic C, mineral N and P background concentrations to investigate the effects of HCA in combination with ¹³C-labelled glucose and mineral P fertilization on greenhouse gas emissions, soil nutrient status (dissolved organic C (DOC), nitrate (NO₃^-), extractable P), and microbial biomass growth. The experiment had a factorial design of one N level × two P levels × six C treatments (control, wheat straw, poplar sawdust, glucose, and combinations of wheat straw or sawdust with glucose). The HCA increased the cumulative CO₂ and CH₄ emissions but decreased N₂O emission, except for wheat straw. Addition of ¹³C-labelled glucose decreased the cumulative CH₄ emission by 59 and 85 % in the sawdust and sawdust + P treatment, respectively. Glucose application reduced the NO₃^- content in the HCA-amended soil by 26-64 %, while P fertilizer further decreased the NO₃^- content in the wheat straw and sawdust treatments by 20 and 24 %, respectively. Both HCA and glucose treatments promoted microbial biomass growth and reduced the soil mineral N content. The δ¹³C of microbial biomass (δ¹³C_MB) showed an increasing trend during the whole experiment, although ¹³C-labelled glucose was added only once at the beginning of the experiment. Addition of HCA decreased δ¹³C_MB, while P addition had the opposite effect. In conclusion, adding a readily available C source to HCA may increase the efficacy of retaining N in post-harvest soils, particularly of more recalcitrant types of HCA like sawdust.

Bioindicators are living organisms that are successfully used for monitoring changes in the environmental health due to natural and/or anthropogenic influences. Dragonflies (Odonata) are considered to be good indicators of water quality; however, research on dragonflies as potential indicators of radioactivity is scarce. The aim of this study was to evaluate dragonflies as potential biological indicators of ionising radiation in nature by measuring ¹³⁷Cs activity concentrations in the dragonfly and river water samples. Altogether, 11 collective samples of dragonflies were collected from the bank of the Mura-Drava-Danube Biosphere Reserve, in the area of Virovitica-Podravina County. Following the initial sample preparation, the gamma spectrometry technique, employing an ORTEC HPGe detector system, was utilised to determine the activity concentrations of ¹³⁷Cs. The results show that the activity concentrations of ¹³⁷Cs in the river water were in the range from 4 to 13 Bq/m³. The results of dragonfly samples showed that ¹³⁷Cs was in the range from 1.7 to 3 Bq/kg. This was more than a hundred times higher than in the river Drava water. According to the obtained results, we conclude that dragonflies could be used as potential bioindicators of radioactivity.

This study investigates the spatial distribution of longevity levels, deuterium in drinking water, and cancer incidence rates, and further examines the impact of deuterium in drinking water on longevity and cancer incidence. Methods such as correlation coefficients and Kriging spatial interpolation were employed to uncover the characteristics of spatial distribution and identify correlations. Findings reveal that regions with higher longevity levels are mostly located on the eastern side of the Hu Huanyong Line (Heihe-Tengchong Line). Deuterium in drinking water decreases from low latitude, low elevation, and coastal areas to high latitude, high elevation, and inland regions. Notably, there is a positive correlation between deuterium content in drinking water and longevity levels, indicating that higher deuterium content is associated with increased longevity. Additionally, counties with lower deuterium content in drinking water show a reduced incidence of cancer cases.