Isotopes in Environmental and Health Studies最新文献

Over 50% of the annual dosage is caused by inhaling radon, thoron, and their decay products. Additionally, indoor concentrations of radon and thoron's decay agents are primarily responsible for the inhalation doses linked to these gases. This study aimed to measure the activity of radon in soil of Nizampur, and associated cancer risk using an RAD7 detector. The range and average values of radon in soil were found to be 994-14,700 Bq m^-3 and 6184 Bq m^-3, respectively. Radon exhalation rate ranged from 220 to 3442 Bq m^-2 h^-1 with an average value of 1447 Bq m^-2 h^-1. The statistical analysis of radon in the soil shows that due to possible localized sources or measurement inconsistency, ambient radon data often exhibits mild skewness or kurtosis, which is shown by minor deviations at the extremes (tails). Based on the values of radon exhalation rate which were found higher than the world permissible value of 57.60 Bq m^-2 h^-1, it is concluded that the soil of the study area may pose health hazards if it is used for construction or other purposes.

Online liquid chromatography (LC) followed by isotope ratio mass spectrometry (IRMS) is a trusted technique to detect honey adulteration based on the stable carbon isotope composition (δ¹³C) of trisaccharides, disaccharides, glucose and fructose. However, LC-IRMS demands specialised analytical setups not commonly found in most isotope labs. Here we investigate the use of off-line LC followed by elemental analysis (EA)-IRMS as an alternative employing more commonly available instruments. Precision and accuracy were excellent for fructose and glucose (error < 0.1 mUr), but less so for disaccharides and trisaccharides, which are similar results to online LC-IRMS. Therefore, offline LC-EA-IRMS can be a viable alternative for the analysis of honey purity employing stable carbon isotopes.

Biological samples collected during oceanographic research are often chemically preserved to maintain tissue integrity prior to analysis. However, chemical preservation can produce changes in isotopic signatures and elemental compositions of the preserved samples. These changes typically adhere to predictable ranges, but effects vary by species. The impacts of two commonly used chemical preservatives, formalin and ethanol, were tested on tissue samples from Atlantic bluefin tuna (Thunnus thynnus) and Atlantic bonito (Sarda sarda). Tissue samples underwent bulk isotope signature and elemental analysis for δ¹⁵N, δ¹³C, %N, %C, and C:N before chemical preservation and again after 1, 3, and 12 months. Significant increase in δ¹⁵N occurred after preservation in both formalin and ethanol (12-month preservation: +0.95 ‰ ± 0.2 formalin, +0.83 ‰ ± 0.3 ethanol T. thynnus; +0.9 ‰ ± 0.2 formalin,+0.86 ‰ ± 0.2 ethanol S. sarda). In most cases, a significant decrease in δ¹³C after preservation was observed, but the effect from formalin was most extreme (12-month preservation: -2.93 ‰ ± 0.2 formalin, -0.34 ‰ ± 0.4 ethanol T. thynnus; -2.86 ‰ ±0.2 formalin,-0.33 ‰ ±0.1 ethanol S. sarda). Changes to tissue C:N ratio were significant after preservation in formalin (+0.18 ± 0.1 T. thynnus; + 0.27 ± 0.1 S. sarda), but not after preservation in ethanol. Similarities in changes of each parameter were observed between both Scombrid species. The observed changes in δ¹⁵N (∼1 ‰) were minor relative to expected differences between trophic levels (3-5 ‰). However, decrease in δ¹³C by formalin (∼3 ‰) may result in misinterpretation of primary producer communities if corrections for preservation effect are not done. Changes in elemental composition (%N, %C, and C:N) were more variable. The mechanisms by which chemical preservatives interact with tissue carbon and nitrogen require further study to explain the relative changes in elemental composition over time.

The increase in urbanisation imposes important threats to biodiversity through habitat destruction, reduced availability of preferred food resources and higher pollution. To support future urban planning, it is necessary to gather more knowledge on how the ecology of organisms from different trophic levels varies across the urbanisation gradient. In our study, we employed carbon and nitrogen stable isotope analysis to investigate the relationship between increasing urbanisation and δ¹³C and δ¹⁵N values across a tri-trophic system of trees (birch and oak), invertebrates (aphids, other Hemiptera, and caterpillars) and a model avian species for urban ecology (the blue tit Cyanistes caeruleus). For the blue tits, we measured the isotopic niche to assess how urbanisation affect niche width at different life stages (adults and nestlings). We observed higher δ¹⁵N values in all taxa in urban areas and δ¹³C values were also higher in urban trees and blue tit nestlings. Exposure to increased air pollution in urban areas, mainly derived from anthropogenic NO_x gas emissions, is one of the main causes of the increase in δ¹⁵N in urban organisms. Furthermore, in urban areas covered by impervious surfaces there is greater water scarcity in the soils, leading to physiological responses in plants that increase the δ¹³C in leaves. We observed that the isotopic niche of urban blue tits is 4.5-18 times smaller in adults and nestlings, respectively, than that observed for forest individuals. Forest blue tits exhibit broader niches, likely reflecting a greater availability and diversity of optimal resources in less disturbed habitats. Conversely, urban blue tits exhibited narrower isotopic niches, suggesting an impact associated with lower diversity and abundance of profitable prey in urbanised habitats. Our study highlights that urbanisation can affect organismal physiology across different trophic levels in similar fashion.

Stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) are increasingly employed to study the foraging ecology of ectothermic predators like crocodilians. However, accurate and precise estimations of trophic discrimination factors between diet and crocodile tissues (Δ¹³C and Δ¹⁵N) from captive experiments under controlled conditions are necessary to reliably quantify the contribution of different prey items make to their diet. The issue of an isotopically constant diet which leads to isotope equilibrium is an important factor influencing accurate estimations of diet-tissue discrimination factors. We raised Nile crocodiles (Crocodylus niloticus) under controlled experimental conditions feeding them with two isotopically distinct (but constant) diets until tissues reached isotopic equilibrium. We sampled blood (plasma and red blood cells, RBC), scute keratin and collagen, and nail tissues throughout the experiment to estimate diet-tissue discrimination factors. Overall, our estimations of average diet-tissue discrimination factors for δ¹³C were +0.2 ‰ for plasma, +0.1 ‰ for RBC, +0.2 ‰ for keratin, +1.9 ‰ for collagen, and +1.2 ‰ for nail tissue, while for δ¹⁵N values were -0.6 ‰ for plasma, +1.5 ‰ for RBC, +1.5 ‰ for keratin, +2.3 ‰ for collagen, and +1.8 ‰ for nail tissue. Body size did not have a significant effect on these tissue estimates, but plasma Δ¹⁵N was influenced slightly. Understanding these differences in ectotherm isotope ecology is crucial for interpreting trophic relationships within food webs that include animals such as reptiles.

Humans are daily exposed to natural background radiations. These are from terrestrial, extra-terrestrial, and anthropogenic radiation sources. Soil is one of the largest contributors to terrestrial radioactivity. The aim of this research was to assess the concentrations of the primordial radionuclides uranium (²³⁸U), thorium (²³²Th) and potassium (⁴⁰K) as well as radiological hazard parameters in soil samples selected from Al-Salam playground in Al-Najaf governorate of Iraq. Gamma ray spectroscopy and a CR-39 detector were used to evaluate both external exposure and internal exposures arising from radon concentrations, respectively. The average activity concentration (Bq kg^-1) for ²³⁸U, ²³²Th, and ⁴⁰K were 17.48 ± 1.89, 8.59 ± 0.77, and 298.31 ± 18.40, respectively. Quantified radiological risk factors were 116.23 ± 5.76 µR h^-1 (exposure), 0.142 ± 0.007 (external hazard (H_ex), 25.71 ± 1.28 nGy h^-1 (absorbed dose rate (D_r), 0.031 ± 0.001 (annual effective dose outdoor (AED_outdoor), and 0.110 ± 0.005 (cancer risk (ELCR × 10^-3), respectively. It was concluded that all values of the activity concentration for natural radionuclides and radiological hazard parameters in study area were within safe limits based on standards set by UNSCEAR, ICRP, and OECD.

The daily distribution of ⁷Be surface air concentration shows a right-skewed pattern, with a mean of 2.37 ± 1.47 mBq m^-3 (AM ± SD) and a geometric mean of 1.88 mBq m^-3 and a CV of 62 %. Principal componentanalysis (PCA) revealed positive correlations between ⁷Be surface air concentration with temperature and wind speed and negative with precipitation and month of the year. Rainfall significantly affects ⁷Be content and masks the impact of other variables on them. Precipitation under 1 mm reduces ⁷Be in air by 1.5 times, with increasing amounts having a greater effect. Rain duration and intensity impact remaining ⁷Be levels, with longer and lighter rains more effective at removal. When the influence of the rains is excluded, the ⁷Be surface air concentration correlates positively barometric pressure and negatively with sunspot numbers. Additionally, it is observed that relative humidity values above 60% significantly decrease ⁷Be in the air. A seasonal pattern in ⁷Be surface air concentration is evident, with peaks during dry and warm months. In March, the mean concentration is 3.4 times higher than in September. This pattern results from various factors showing seasonal behaviour. During dry months, increased temperature, barometric pressure, and wind speed contribute to higher ⁷Be content. In contrast, during rainy months, precipitation and high relative humidity act as key factors in reducing ⁷Be levels in surface air. And for this region, the horizontal influx of beryllium-rich air masses plays a larger role in the ⁷Be surface air concentration than the vertical influx from higher atmospheric layers. Rainfall is the primary cause of the decrease in ⁷Be surface air concentration. Following rainfall, the atmosphere gradually is restored in ⁷Be content, following a saturation curve, with reload coefficient of 0.36 ± 0.05 d^-1 and a recharge time of 2.8 ± 0.2 d.

Natural radioactivity is receiving a lot of attention worldwide due to its essential role in human health. Sugar is a generic term for sweet, soluble carbohydrates, many of which find their way into food. Therefore, measuring natural radioactivity is critical as it has a direct impact on human safety. This research analyzed natural radionuclide activity levels in 22 samples of commonly consumed sugar from the Kurdistan Region of Iraq. High-purity germanium (HPGe) detectors are used in gamma-ray spectrometers. Measurements in this study showed that ²²⁶Ra activity concentrations ranged from below minimum detectable activity (BMDA) to 5.16 ± 2.55 Bq kg^-1 with an average value of 0.80 ± 0.15 Bq kg^-1. In contrast, ²³²Th radionuclide activity concentrations ranged from BMDA to 3.11 ± 1.67 Bq kg^-1 with an average value of 0.51 ± 0.10 Bq kg^-1. Also, the activity concentration of ⁴⁰K ranged from BMDA to 30.71 ± 10.77 Bq kg^-1 with a mean of 6.44 ± 2.54 Bq kg^-1. Based on these results, a radiation risk index associated with sugar intake was calculated. It was verified that the radiation exposure due to sugar consumption in the Kurdistan Region of Iraq was below the permissible level of 290 μSv y^-1, and did not pose a radiation risk to public health.

In this study, ²²²Rn and ²²⁶Ra activity concentration, annual effective dose and radon exhalation rate were measured in samples of building materials and soils collected from the city of Rawalakot in Azad Kashmir. The samples were measured using the passive technique with CR-39 detectors. ²²²Rn activity concentration in sand, brick, blocks, soil and tiles varies from 259 to 401, 230-464, 273-421, 256-523 and 267-438 Bq/m³, respectively. The annual effective dose for people living in built environments with sand, bricks, blocks, soil and tiles ranges from 4.0-6.32, 3.62-7.31, 4.30-6.63, 4.03-8.24 and 3.36-6.90 mSv/y, respectively, and the mean values are 5.16, 5.31, 5.31, 5.56 and 5.26 mSv/y. The radon activity concentration results were compared with the limits set by the Health Protection Agency UK (200 Bq/m³), US-EPA (148 Bq/m³) and WHO (100 Bq/m³). Some samples exceeded these recommended limits, indicating a potential health risk.

Assessing soil radioactivity and associated risks in areas surrounding gas fields is essential due to potential natural radionuclide accumulation during extraction activities. This study investigates the radioactivity levels in surface soil from the Haripur gas field. 21 soil samples were analyzed using a high purity germanium (HPGe) detector. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in the soil samples were found to range between 11-19, 20-38, and 280-500 Bq kg^-1, respectively. All ²²⁶Ra values and the majority of ²³²Th and ⁴⁰K values fell within the global average levels for soil, which are 35, 30, and 400 Bq kg^-1, respectively. Radiation hazard indices were found to be below the internationally accepted safety limits set by organizations such as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the International Commission on Radiological Protection (ICRP), indicating that the soil poses no significant radiological risks for construction and agricultural applications. This research offers essential baseline data on soil radioactivity at the Haripur gas field, supporting public health, environmental protection, and regulatory compliance efforts.