ABSTRACT Dietary variation at the individual level plays a fundamental role in carotenoid-based ornamental plumage coloration, which often influences sexual and social signaling. This study investigated how dietary differences shape the coloration of two ornamental feather types (breast and forehead) in males of the saffron finch. This small neotropical bird is considered granivorous, although it frequently incorporates arthropods into its diet. We used reflectance-based color measurements and carbon and nitrogen stable isotopes (δ¹³C, δ¹⁵N) to infer dietary patterns and their association with color variation. A total of 29 males were sampled across seven field campaigns conducted between January 2017 and March 2018 in a farm located in the Central Brazilian savannas. δ¹³C values showed no association with breast or forehead coloration, indicating that variation in carbon sources was not a major driver of color expression. In contrast, δ¹⁵N values were significantly associated with hue variation in both feather types. Higher δ¹⁵N values corresponded to a yellower-shifted hue in breast feathers and red-shifted hues in forehead feathers. Taken together, these findings suggest that saffron finches may selectively forage on high-trophic level prey that are relatively rich in carotenoids and associated with improved nutritional conditions. This dietary variation may be linked to differences in carotenoid processing and allocation across feather patches, contributing to different color phenotypes. In addition, such diets are associated with the production of high-quality feathers and promote more elaborate ornamental coloration. Although δ¹⁵N values may also be influenced by baseline variation in nitrogen sources, the observed patterns are consistent with trophic differences and highlight the role of diet in shaping plumage coloration. Our results highlight the importance of individual dietary strategies in shaping carotenoid-based color phenotypes through both direct (carotenoid acquisition) and indirect (nutritional condition) pathways, with distinct effects across different ornamental feather regions.

ABSTRACT Mechanical grinding is increasingly used in samples preparation for stable isotope analysis. However, plastic abrasion could contaminate samples and bias the isotopic analysis. Previous studies on plant material and large quantity of marine animal samples showed that this bias is limited. However, there is no evaluation of this potential contamination on smaller animal samples. We evaluate potential plastic contamination by analysing the C and N elemental composition and stable isotope values of ∼50 mg (dry weight) of samples of a freshwater crustacean hand-ground versus mill-ground for durations of 1, 2 and 5 min. We found no differences in %N among treatment groups, but an increase in the %C with ball milling time, with significant differences between samples hand ground and mill-ground for 2 min, hand ground and mill-ground for 5 min, and mill-ground for 1 min and mill-ground for 5 min. No significant differences in neither the δ 15N nor δ 13C were found among the four grinding methods. We estimated plastic abrasion to be 1.65 mg. Our results show that the use of ball milling for homogenising samples for C and N stable isotope analysis does not affect animal muscle samples with a commonly used amount of material (∼50 mg). Finally, we provided a graphical recommendation on the minimum amount of sample to be ground by milling without incurring in plastic contamination bias.

ABSTRACT This paper describes a simple method for the simultaneous determination of the isotopic composition (δ 13CCO2) and concentration of CO2 in volcanic and geothermal gases using a continuous flow mass spectrometry system (CF-IRMS). The instrumental configuration includes a Thermo Fisher Scientific Delta Q mass spectrometer, connected through a Conflo IV to a Thermo Trace 1610 gas chromatograph (GC) physically connected at the module Isolink II. The performance of the developed GC-IRMS method was evaluated through a comprehensive series of tests assessing the precision and accuracy of the δ 13C values and the simultaneous determination of CO2 concentrations. Specifically, we evaluated instrumental precision and isotopic data reproducibility (δ 13CCO2) under various gas chromatographic operating conditions (split ratio) using gas mixture and certified isotopic standards; concentration calibration curves were specifically developed at different split ratios (3, 20, 35, and 45) using certified gas mixtures to quantitative CO2 determination with a wide concentration range (from 0.06–100 % vol.). The concentration data were compared with those obtained with traditional analytical techniques (GC and IR). Subsequently, the entire system performance, for both isotopic composition and CO2 concentration, was validated on volcanic and geothermal gases. These samples, including fumaroles, bubbling pools, and soil gas emissions, were selected to test the simultaneous determination capability under real-world conditions. The results confirm that the achieved operating configuration ensures optimal performance for the simultaneous determination of δ 13CCO2 and CO2 concentrations, guaranteeing a precision of ± 0.08 ‰ and an accuracy within ± 0.1 ‰ for isotopic data and a quantitative accuracy typically within ± 5 % for concentration data.

ABSTRACT The provenance, antiquity, duration of production, animal husbandry and geographical location of materials used to make one of the largest feather art objects ever produced are explored via analysis of four stable isotopes (δ 2H, δ 18O, δ 13C and δ 15N) combined with radiocarbon measurements. We document the monotonously fed rearing of thousands of captive macaws in the Amazon region and the acquisition of camelid fibres from the high Andes to produce ninety-six large feather panels. Multiple radiocarbon dates from both feathers and fibres confirm the Wari (600–100 AD) origin of the panels and suggest a short and intensive production schedule. Stable isotopes document the collection of materials that took the artisans over hundreds of kilometres from the Amazon to near the Pacific coast.

ABSTRACT In the present investigation, a total of 62 potable water samples were analyzed to assess uranium concentrations and the associated toxicological and radiological risks from the eastern region of Kumaun Himalaya, India, using LED fluorometry technique. The Oakton Benchtop device was used to measure physicochemical parameters, including pH, temperature, total dissolved solids and electrical conductivity. Uranium concentration in water samples ranged from 0.5 ± 0.1 to 96.1 ± 0.7 µg/L, with a mean value of 23.5 ± 27.7 µg/L; with 16 % of the water samples exceeding the provisional guideline value (30 µg/L) provided by the World Health Organization. Comparative analysis reveals that hand-pumped water showed a higher average (40.3 µg/L) than tap and spring water sources. Nevertheless, all samples remain below the radiological-based limit set by the Atomic Energy Regulatory Board. Radiological risks were evaluated by calculating annual effective doses and excess cancer risk. Results indicated that estimated annual effective ingestion doses for different age groups and genders were comparatively higher in males. Further, chemical risks were quantified by estimating the lifetime average daily dose and health quotient. The average excess cancer risk was found to be 3.23 × 10–5, with lifetime average daily dose ranging from 0.003 to 2.75 µg/kg/day, averaging 0.66 µg/kg/day. The investigation found no significant chemical toxicity from uranium in water, as the computed health quotient was below 1. A strong correlation was observed between uranium and total dissolved solids, with a Pearson's r value of 0.82. Statistical model, including ANOVA, indicates that the rock/soil types of the study area contribute to the uranium distribution over the region. Further, cluster analysis was also performed on the obtained data. The findings of the present study indicated that the sedimentation zone near river confluences shows elevated uranium content, likely due to the leaching of soil/rocks from the upper Himalayan terrain.

ABSTRACT The rapid development of industries near forest and river has led to concerns about the toxic metal contamination of agricultural land following the release of radiotoxic elements. The study area, characterized by agricultural land influenced by the Jamuna River, Madhupur forest and numerous industries, has been assessed for concentrations of natural radionuclides and associated radiological hazards. A total of 48 agricultural soil samples were collected from twelve upazilas of the Tangail district. The measurement was performed using gamma-ray spectrometry, employing a high-purity germanium (HPGe) detector. The measured mean activity concentrations of ²²6Ra, ²³²Th, and 40K in soil samples were found to be 25.63 ± 5.00, 43.63 ± 2.00, and 451 ± 15 Bq kg−¹, respectively. The mean radium equivalent activity, absorbed dose rate for indoor and outdoor environments, and indoor and outdoor annual effective doses were lower than the world average value. Hazard indices such as external hazard index (Hex), and internal hazard index (Hin) were found to be less than unity. However, the gamma index (Iγ) was found higher than unity for some locations. The annual gonadal dose equivalent (AGDE) and excess lifetime cancer risk (ELCR) exceeded the global average. These findings are likely attributed to the natural environmental features of Tangail, including the geological characteristics of the Jamuna River, Madhupur forest, and industrial regions. The presented data may serve as the baseline radioactivity data for this area and may be useful for assessing any future radiological risk of this region.

ABSTRACT This study investigates the activity concentrations of naturally occurring radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in poultry feed samples collected from thirty different commercial and local production sites across Erbil Province, Iraq. Using high-purity germanium (HPGe) gamma-ray spectrometry, a total of 30 poultry feed samples were analyzed to assess radiological safety and evaluate potential exposure risks through the poultry food chain. The measured activity concentrations ranged from 0.18–5.27 Bq kg−¹ for ²²⁶Ra, below detection to 5.16 Bq kg−¹ for ²³²Th, and 46.12–268.20 Bq kg−¹ for ⁴⁰K. The mean concentrations of 1.556 Bq kg−¹ (²²⁶Ra), 1.34 Bq kg−¹ (²³²Th), and 167.52 Bq kg−¹ (⁴⁰K) were all moderately low compared to other countries' work. Regional variation in radionuclide levels was observed, particularly for ²²⁶Ra and ²³²Th, with the highest levels detected in samples from Pirmam, potentially due to geogenic factors or mineral-based additives. Descriptive statistics and histogram analysis showed that ⁴⁰K concentrations followed a near-Gaussian distribution, while ²²⁶Ra and ²³²Th exhibited positive skewness. Comparative analysis with data from other countries confirmed that the activity concentrations in this study were significantly lower than those reported in Nigeria, Serbia, and Uganda. This research provides a vital radiological baseline for poultry feed in the region and demonstrates that the feeds currently used in Erbil pose no significant radiological hazard to poultry or human health. These findings emphasize the importance of continued surveillance of feed materials, especially in regions with diverse geological sources, to ensure food chain safety and compliance with international radiological protection standards.

ABSTRACT Exposure to radon contributes to more than 50 % of the total radiation dose received from natural sources by human beings; therefore, radon measurements are crucial in monitoring human health and safety. It can migrate from the soil into plants, further contributing to human exposure through the consumption of contaminated vegetables. The present study aims to determine the concentration of radon in 18 different types of vegetable collected from Bazyan location in Kurdistan Iraqi region which are frequently consumed because most of the population in Kurdistan depend on those vegetable foods. In methodology, CR-39 detector and PVC tube were used to record the tracks of alpha particles released from the radon content within the vegetable samples. The results showed that the concentration levels of radon in vegetable samples ranged from the highest value 310.963 Bq m−3 in the green peppers sample to lowest value 9.830 Bq m−3 in the wild rocket sample, with an average concentration in the samples of 161.965 Bq m−3. Therefore, the concentrations of radon in vegetable samples were lower than the global permissibility limit of exposure to radon according to the International Commission on Radiological Protection and the International Atomic Energy Agency (200–800 Bq m−3). Results were also found to be lower than the 400 Bq m−3 according to ICRP in foods; therefore, this will not form any risk on human life.

ABSTRACT The beach sediments in northern Vietnam were analysed for grain size, minerals and radionuclides in 24 samples. Grain size was measured by sieving, minerals by XRD and radionuclides by gamma-ray spectrometry. The radiological risk indices Raeq, ADR, AEDE, Iγr, AUI, Hex, AGDE and ELCR were evaluated. There were three types of sediment: very fine sand, fine sand and medium sand. Very fine sand with a mean diameter (Md) of 105 µm, fine sand with an Md of 192 µm and medium sand with an Md of 330 µm were used. The percentages of minerals with quartz, illite, feldspar, kaolinite, chlorite, goethite, gibbsite and amphibole contents were 80.6, 5.4, 3.3, 2.4, 2.0, 2.0, 0.2 and 0.8 %, respectively. The average radioactivity of 238U, 226Ra, 232Th and 40K was 23.3, 23.1, 27.1 and 214.9 Bq/kg, respectively. The radiological risk indices, including Raeq, ADR, AEDE, Iγr, AUI, Hex, AGDE and ELCR, were 78.38 Bq/kg, 38.8 nGy/h, 0.04 mSv/yr, 0.57, 0.56, 0.21, 256.1 µSv/y and 0.16 × 10−3, respectively. The origin of radioisotopes is mainly in sediments and from mainland, which are influenced by minerals and grain sizes. Additionally, another source from seawater or the atmosphere plays a minor role. The average radioactivity and radiological risk indices were lower than the global average and the recommendation of UNSCEAR, so sediments were safe for humans and organisms.

ABSTRACT Quantifying rates of nitrogen (N) fixation in complex biological systems is of specific and acute interest to a wide array of ecological, agricultural, and soil scientists. N-fixation assays are commonly achieved through incubation of the target system with N2 gas that is greatly enriched in the less abundant heavy isotope, 15N. However, contamination of 15N2 gas supplies with more biologically available N species, such as ammonia and nitrate/nitrite can profoundly interfere with such assays and lead to false positives and/or inflated estimates of N-fixation rates. Here, we identify the ongoing contamination of commercial 15N2 stocks and quantify the potential impact to organismal and soil N-fixation studies. Further, we provide recommendations for mitigating and correcting for the effects of contamination in gas stocks, and present a simple, rapid procedure for quantification utilizing the same instrumentation that is typically employed to analyse N isotope ratios in N-fixation studies.