Isotopes in Environmental and Health Studies最新文献

Terrestrial gamma radiation is one of the major outdoor radiation exposures to the general public that varies substantially based on the type and geological properties of the soil. The objective of this study is to evaluate the naturally occurring radioactive materials (NORMs) distribution and assess the hazard parameters in the riverbank soil within various industrial zones in the densely populated Dhaka and Chattogram cities of Bangladesh. The mean activities of ²²⁶Ra (37 ± 3), ²³²Th (58 ± 4), and ⁴⁰K (1129 ± 18) Bqkg^-1 in the assessed soil samples were found to be slightly higher than the world average values 32, 35, and 420 Bqkg^-1, respectively. The mean radium equivalent activity (207.49 Bqkg^-1) and the external and internal hazard indices were within the recommended limits of 370 Bqkg^-1 and <1, respectively. The mean absorbed dose rate (99.47 nGyhr^-1), annual effective dose (0.12 mSva^-1), ELCR (4.27 × 10^-4), and gamma level index (1.58) exceeded the world average values 59 nGyhr^-1, 0.07 mSva^-1, 2.9 × 10^-4, and 1 respectively. However, the studied areas are safe from a radiological viewpoint with no radiation health hazard to the people. The results of this study can be utilized to produce factual baseline data for future studies.

Isotope technology is widely used in geochemical mechanisms analysis; however, studies on the origin of pit lake water by isotopes in coal concentration areas in grassland are rare. In this study, 20 groups of water samples were collected, which were subjected to chemical analysis to determine the hydrogeochemical characteristics of pit lake water. The mechanisms of pit lake water formation and recharge-evaporation were ascertained through principal component analysis and the Rayleigh fractionation model. The results indicate that the phreatic water is least affected by evaporation, followed by confined water, surface water and pit lake water. The ionic composition of surface water, phreatic water and most of the confined water is mainly affected by leaching, some confined water can be recharged by surface or phreatic water; while the ionic composition of pit lake water is dominantly affected by evaporation (69.4 %) and is less affected by groundwater recharge (17.1 %) and human activities (11.5 %). The pit lake water is recharged by precipitation, phreatic water and the lateral runoff of confined water; however, the proportion of phreatic and confined water recharge is small. The evaporative loss of the pit lake water is 40-61 % of the initial water body.

We investigated the stable isotope hydrology of Sable Island, Nova Scotia, Canada over a five year period from September, 2017 to August, 2022. The δ²H and δ¹⁸O values of integrated monthly precipitation were weakly seasonal and ranged from -66 to -15 ‰ and from -9.7 to -1.9 ‰, respectively. Fitting these monthly precipitation data resulted in a local meteoric water line (LMWL) defined by: δ²H = 7.22 ± 0.21 · δ¹⁸O + 7.50 ± 1.22 ‰. Amount-weighted annual precipitation had δ²H and δ¹⁸O values of -36 ± 11 ‰ and -6.1 ± 1.4 ‰, respectively. Deep groundwater had more negative δ²H and δ¹⁸O values than mean annual precipitation, suggesting recharge occurs mainly in the winter, while shallow groundwater had δ²H and δ¹⁸O values more consistent with mean annual precipitation or mixing of freshwater with local seawater. Surface waters had more positive values and showed evidence of isolation from the groundwater system. The stable isotopic compositions of plant (leaf) water, on the other hand, indicate plants use groundwater as their source. Fog had δ²H and δ¹⁸O values that were significantly more positive than those of local precipitation, yet had similar ¹⁷O-excess values. δ²H values of horsehair from 4 individuals lacked seasonality, but had variations typical to those of precipitation on the island. Differences in mean δ²H values of horsehair were statistically significant and suggest variations in water use may exist between spatially disparate horse communities. Our results establish an important initial framework for ongoing isotope studies of feral horses and other wildlife on Sable Island.

Argentina is a Latin American country which encounters soil degradation problems. The most productive regions have implemented conservative land practices (no-till). However, agricultural frontier has been displaced to marginal lands with arid and semiarid climates, with the consequent disappearance in many areas of native forest and land degradation. In this work, the fallout of gamma-emitting radionuclides, ¹³⁷Cs and ⁷Be, was jointly used to assess changes in soil erosion in a recently converted semiarid ecosystem into agricultural land. ¹³⁷Cs was utilized to estimate the erosion over the past 60 years, whereas ⁷Be was employed to estimate the erosion after the conversion of the area to cultivated land and soil tillage. For ¹³⁷Cs the Proportional Model (PM), the Mass Balance Model II (MBMII) and the MODERN model were used, for ⁷Be the Profile Distribution Model (PDM) and the MODERN model were used. ¹³⁷Cs indicates mean erosional rates of 8.2, 10.5 and 6.5 Mg ha^-1 a^-1, using MBMII, PM and MODERN, respectively, and that a soil layer between 0.5 and 0.8 mm was annually lost by erosion. By applying a ⁷Be tracer, we measured erosion rates of 2.4 and 3.3 Mg ha^-1 (with PDM and Modern, respectively), indicating the loss of the upper 0.2 mm of soil. This erosion can be attributed to a few heavy rainfalls that occurred within the past 90 days. The results suggest that current land management practices have led to an increase in soil erosion. This could be attributed to the fact that the soil remains bare after crop harvest, which may compromise its conservation and future productivity.

We characterized the elemental and C and N stable isotope compositions of Tillandsia fasciculata Sw., Tillandsia balbisiana Schult. & Schult.f. and Tillandsia recurvata (L.) L. samples collected in Cienfuegos (Cuba). Results showed high enrichment factors for S, Hg, Cd, Pb, P, Zn, Cu, Mo, Sb and Ca in all Tillandsia species, indicating inputs from local anthropogenic activities (road traffic, industries and cement production). Carbon concentrations and δ¹³C varied from 38.3-47.7 % and -20.4 to -13.4 ‰ within the three species, respectively. δ¹³C showed seasonal dependence with the dry and wet periods and more ¹³C-depleted values in urban/industrial areas, coherent with the input of anthropogenic emissions. Nitrogen concentrations (0.4-1.3 %) and δ¹⁵N values (-9.9-4.4 ‰) exhibit larger variations and are positively correlated in the three species. The most positive δ¹⁵N in T. recurvata (-0.2-4.4 ‰) are attributed to contributions from industrial activities and road traffic. In fact, both δ¹⁵N and total nitrogen (TN) values increase in sites with higher road traffic and show significant correlations with typical road traffic and industrial tracers. Finally, we calculate an average total nitrogen deposition rate of 4.4 ± 2.3 kg ha^-1 a^-1 from N content in T. recurvata, similar to the existing values determined in the region by field measurements, but higher than the global terrestrial average.

The biogeochemical consequences of dihydrogen (H₂) underground storage in porous aquifers are poorly understood. Here, the effects of nutrient limitations on anaerobic H₂ oxidation of an aquifer microbial community in sediment microcosms were determined in order to evaluate possible responses to high H₂ partial pressures. Hydrogen isotope analyses of H₂ yielded isotope depletion in all biotic setups indicating microbial H₂ consumption. Carbon isotope analyses of carbon dioxide (CO₂) showed isotope enrichment in all H₂-supplemented biotic setups indicating H₂-dependent consumption of CO₂ by methanogens or homoacetogens. Homoacetogenesis was indicated by the detection of acetate and formate. Consumption of CO₂ and H₂ varied along the differently nutrient-amended setups, as did the onset of methane production. Plotting carbon against hydrogen isotope signatures of CH₄ indicated that CH₄ was produced hydrogenotrophically and fermentatively. The putative hydrogenotrophic Methanobacterium sp. was the dominant methanogen. Most abundant phylotypes belonged to typical ferric iron reducers, indicating that besides CO₂, Fe(III) was an important electron acceptor. In summary, our study provides evidence for the adaptability of subsurface microbial communities under different nutrient-deficient conditions to elevated H₂ partial pressures.

The extraction of lipids by the Folch method from the muscles of all the fish studied led to statistically significant differences in the values of δ¹⁵N. At the same time, lipid extraction led to a statistically significant increase in δ¹³C in pike and roach, and to a statistically insignificant decrease in δ¹³C in perch and bream. Thus, lipid extraction cannot serve as a universal method of sample preparation for the analysis of the isotopic composition of carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) in fish muscles. The differences between the δ¹³C values in the samples before and after lipid extraction were statistically investigated by different models. It is shown that mathematical correction method models can be used, but the results are depending on the fish types.

In Taiwanese volcanic watersheds, we investigated stable water isotopes in meteoric water, plants, and thermal water. Meteoric water exhibited a seasonal cycle, with heavier isotopes in winter and lighter ones in summer, especially in the southern region. The northern monsoon signal lagged the south by two weeks. In the Tatun mountains, young water fractions indicated prevalent old water sources. In the northern watershed, streamwater mainly came from the winter monsoon, while the southern one was influenced by alternating monsoons. Both indices indicated that winter plants depended on summer rainfall. Streamwater and plants had distinct sources in winter, supporting ecohydrological separation. Thermal spring water's d-excess helped identify water-rock interactions, with low d value signaling such interactions. The topographic wetness index showed a higher summer monsoon contribution to southern streamwater but a lower one to plants. The mean linear channel direction significantly affected the monsoon contribution fraction, with northeast-oriented channels vulnerable to northeastward winter monsoons. Finally, we developed a model illustrating hydrological processes on short and long timescales. Our findings enhance our understanding of hydrological disturbances' impact on water resources and ecosystems.

ABSTRACTEnvironmental and health risks posed by radionuclides in quarry pit soils are of great concern in environmental health monitoring. The current investigation was aimed at determining the natural radionuclide activity concentration (in Bq kg^-1) of the understudied quarry pit granules used as construction materials. The collection and preparation of pit soil samples from Abeokuta quarry sites were done using standard methods, analysis of radiological parameters was carried out using hyperpure germanium (HPGe) spectrometer. Specific activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were measured. The values obtained were greater than the world weighted average of 35, 30, and 400 Bq kg^-1 for ²²⁶Ra, ²³²Th, and ⁴⁰K, respectively. The absorbed dose, the annual effective dose, and the radium equivalent were calculated and demonstrated significant values. The radionuclide content of the samples is relatively high and the use of pit soils as a building material, therefore, raises radiological concerns for dwellers in this area and requires periodic monitoring and undergoing a radiation protection program.