Isotopes in Environmental and Health Studies最新文献

Radiogenic isotopes of igneous and detrital minerals from various clastic rocks of mountain belts are used to reveal tectonic and sedimentary processes, which are otherwise difficult to detect. Here, we discuss the results of U-Pb and Lu-Hf zircon systems, and ⁴⁰Ar/³⁹Ar on detrital white mica in Eastern Alps. Zircon and white mica are chemically and mechanically stable and occur in magmatic, metamorphic and sedimentary rocks. During subsequent metamorphism, zircon is resistant against high temperature, >650 °C (U-Pb) and 900 °C (Lu-Hf). The Lu-Hf zircon system is used as a tracer of initial magma separation from the mantle, and the U-Pb zircon system records magmatic crystallization. The ⁴⁰Ar/³⁹Ar white mica system is stable up to 400-450 °C dating either formation or cooling after high-grade metamorphism. Detrital U-Pb zircon ages on two major rivers draining the Eastern Alps do not record any sign of Alpine orogeny or metamorphism. Consequently, U-Pb zircon studies can entirely miss the record of collisional orogeny in cool, magma-poor collision orogens. In contrast, ⁴⁰Ar/³⁹Ar white mica ages record Early and Late Alpine metamorphism but are limited to revealing the pre-orogenic history. U-Pb zircon and ⁴⁰Ar/³⁹Ar white mica yield different information in provenance studies. In the Eastern Alps, U-Pb zircon dating of magmatic and clastic rocks indicates intense formation of magmatic rocks between 630 and 230 Ma. Felsic rocks dominate the older age groups, and increasingly young mafic rocks were dated, specifically between 265 and 230 Ma. Hf isotopes record increasing juvenile input since ∼630 Ma. Two different groups with respect to Mesoproterozoic depleted mantle ages are shown: (1) one group with a Mesoproterozoic age gap typical for Gondwana-derived units, and (2) a rare group with Mesoproterozoic ages recording a new tectonic element in the Austroalpine basement in Alps.

Stable isotopes of chlorine have great application potential due to the widespread occurrence of the chlorine anion in water, minerals, living organisms and the environment. In most studies, the chloride ion from the samples is converted to chloromethane, which is then analysed isotopically using a mass spectrometer. In the present study, a new design for a chloromethane preparation line is proposed. In particular, the new chloromethane preparation line uses a new system for injecting iodomethane into the preparation system, as well as ampoules with Teflon valves and the u-shaped freezers. These improvements reduced the preparation time to about 1 h, and also achieved a decent measurement uncertainty of 0.05 permil.

The impact of freshwater sources like surface river runoff and submarine groundwater discharge (SGD) on coastal waters is currently in focus of intense debate and investigation. One of the ongoing challenges in SGD research is the characterization and quantification of the freshwater endmember contributions to the subsurface mixing zone and their influences on element balance and biogeochemical transformations. Long-term investigations of the sediment porewater composition provide characterization and understanding of the physical, hydrological and biogeochemical processes controlling the substance exchanges. In this study, we focus on the hydrochemical and stable isotope (δ²H, δ¹⁸O) compositions of sediment porewaters along the coastline of a southern Baltic Sea peatland. Coastal surface water and groundwater dynamics were monitored at two coastal sites using 5-m-long stationary lances over a 5-year period.The vertical compositional gradients were used to extrapolate to zero-salinity (ZS) components applying a binary mixing model on the salinity and water isotope composition. The results characterize a subterranean estuary (STE) with three potential mixing endmembers: two fresh groundwaters and the brackish Baltic Sea. Tritium-helium (³H-³He) porewater dating gave ages of more than about 20 years for the freshwater components. The ZS components were compared with other SGD sites along the southern Baltic Sea and North Sea and highlight the importance of local SGD studies for a proper groundwater endmember characterization as basis to understand hydrological and biogeochemical developments at the land-ocean continuum in times of current climate change.

Sulphur and oxygen stable isotopes of sulphate have been used to trace the sources of sulphur into aquatic systems. These isotopes have also been used to understand the transformation and fate of sulphur in the water bodies contaminated by AMD discharge from active and/or abandoned mines. Stable isotopes of oxygen in dissolved sulphate (δ¹⁸O_SO4) and water (δ¹⁸O_H2O) have helped to decipher the sulphide oxidation pathways and estimate their contributions. The present study is focused on analysing the composition of sulphur and oxygen stable isotopes of sulphate and oxygen stable isotope in AMD and Lunar-Lukha River water flowing through the coal mining area of the East Jaintia Hills District, Meghalaya, in order to decipher the sulphide oxidation pathways. The results showed that the sulphur stable isotope of sulphate (δ³⁴S_SO4) ranged between -12.5 and -8.0 ‰ (VCDT). The oxygen isotope of sulphate (δ¹⁸O_SO4) ranged between 1.4 and 2.0 ‰ (VSMOW). The oxygen isotope of water (δ¹⁸O_H2O) was distributed between -6.2 and -4.2 ‰ (VSMOW). Pyrite oxidation was found to be the dominant source of sulphate in the Lunar-Lukha Rivers. The results of the stoichiometric isotope balance model showed that 68-83 % of sulphate derived Fe³⁺ oxidation pathway, with a high portion of sulphate oxygen derived from water. The sulphite-water oxygen exchange model revealed the release of intermediate sulphoxyanions, suggesting the presence of an oxidation pathway of sulphide minerals to sulphate via sulphoxyanions. The results from this study will be helpful in defining effective remediation strategies to mitigate AMD impacts.

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.