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Keywords = isotope ratio analysis

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13 pages, 2458 KiB  
Article
Authentication of Indian Honey Based on Carbon Stable Isotope Ratio Analysis—Verification of Indian Regulatory Criteria
by Ajit Dua, Sanjivan Bahman, Simon Kelly, Shainandni Dogra and Kirti Sharma
Foods 2025, 14(8), 1289; https://doi.org/10.3390/foods14081289 - 8 Apr 2025
Viewed by 417
Abstract
The present study was undertaken for the first time in India to generate a database of isotopic signatures of authentic Indian honey to verify the regulatory criteria laid down by the Food Safety and Standards Authority of India (FSSAI). In this study, ninety-eight [...] Read more.
The present study was undertaken for the first time in India to generate a database of isotopic signatures of authentic Indian honey to verify the regulatory criteria laid down by the Food Safety and Standards Authority of India (FSSAI). In this study, ninety-eight (98) authentic honey samples from nineteen (19) different botanical sources were collected from five (05) geographical regions of India and analyzed to generate a database of stable carbon isotope ratios (13C/12C) by Elemental Analyzer/Liquid Chromatography–Isotopic Ratio Mass Spectrometry (EA/LC-IRMS). The samples were analyzed for the parameters δ13CHoney(δ13CH), δ13CProtein(δ13CP), δ13C individual sugars, ∆δ13CProtein-Honey(δ13CP-H), C4 sugar, ∆δ13CFructose-Glucose(δ13CFru-Glu), ∆δ13Cmax, and foreign oligosaccharides (FOs), as per the official methods of analysis of the Association of Official Analytical Chemists (AOAC 998.12) and the FSSAI. The results were evaluated against the published literature and Indian regulatory criteria for authentic honey. The δ13C value for honey (δ13CH) ranged from −22.07 to −29.02‰. It was found that 94% of Indian honey samples met the criteria for Δδ13CP-H (≥−1.0‰), Δδ13CFru-Glu (±1.0‰), and C4 sugar content (7% maximum), with negative C4 sugar values treated as 0% as prescribed by the AOAC method. Further, 86% of samples met the FO criteria (maximum 0.7% peak area). Thus, the data of this study provide scientific backing for these four (04) parameters as per the FSSAI regulation. However, the non-compliance of a high number (47%) of authentic honey samples for Δδ13Cmax (±2.1‰) compels further systematic investigation with a special focus on bee feeding practices. Further, in the present study, it was found that honey samples with a Δδ13CP-H greater than +1‰ and a C4 sugar content more negative than −7% also did not comply with the Δδ13Cmax criteria. Hence, Δδ13CP-H values (>+1‰ equivalent to C4 sugar < −7%) could be an indicator of C3 adulteration to some extent. Full article
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37 pages, 14137 KiB  
Article
Origin of Siderite and Baryte in a Carbonate-Replacement Ag-Pb-Zn-Cu Sulphide Deposit: Walton, Nova Scotia, Canada
by Chaneil J. Wallace, Daniel J. Kontak, Elizabeth C. Turner and Mostafa Fayek
Minerals 2025, 15(3), 327; https://doi.org/10.3390/min15030327 - 20 Mar 2025
Viewed by 536
Abstract
Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit [...] Read more.
Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit (Nova Scotia, Canada) consists of two ore types: (1) a sulphide body primarily hosted by sideritised Viséan Macumber Formation limestone (0.41 Mt; head grade of 350 g/t Ag, 4.28% Pb, 1.29% Zn, and 0.52% Cu), and (2) an overlying massive baryte body of predominantly microcrystalline baryte (4.5 Mt of >90% baryte). This study used optical microscopy, SEM-EDS, cathodoluminescence (CL), LA-ICP-MS, and SIMS sulphur isotope analysis of siderite and baryte to elucidate their origin and role in deposit formation. Siderite replaces limestone and contains ≤9 wt. % Mn, is LREE-depleted (PAAS-normalised REEY diagrams), and has low (<20) Y/Ho ratios. Sideritisation occurred due to dissimilatory iron reduction (DIR) that led to the breakdown of Fe-Mn-oxyhydroxides and organic matter, as indicated by light δ13CVPBD values and negative Y anomalies. The baryte body is dominated by a microcrystalline variety that locally develops a radial texture and coarsens to a tabular variety; it also occurs intergrown with, and as veins in, massive sulphides. Based on fluid inclusion data from previous studies, the coarser baryte types grew from a hot (>200 °C) saline (25 wt. % NaCl) fluid containing CO2-CH4 and liquid petroleum. Marine sulphate δ34SVCDT values typical of the Viséan (~15‰) characterise the baryte body and some tabular baryte types, whereas heavier (~20‰) and lighter (~10‰) values typify the remaining tabular types. The variations in tabular baryte relate to distinct zones identified by CL imaging and are attributed to the sulphate-driven anaerobic oxidation of methane (SDAOM) and oxidation of excess H2S after sulphide precipitation. These results highlight the importance of hydrocarbons (methane and organic matter) in the formation of both the siderite and the baryte at Walton and that DIR and the SDAOM can be important contributing processes in the formation of SEDEX deposits. Full article
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18 pages, 3892 KiB  
Article
Isotope Ratio Mass Spectrometry (IRMS)-Based Authentication of the Geographic Origins of Volvariella volvacea (Bull.) Singer
by Xing Liu, Qinxiong Rao, Qicai Zhang, Hao Geng, Yangyang Lu, Zhu Liu, Shanshan Chen, Peijun Li and Weiguo Song
Foods 2025, 14(6), 1074; https://doi.org/10.3390/foods14061074 - 20 Mar 2025
Viewed by 203
Abstract
The growing consumption of Volvariella volvacea has heightened concerns regarding its geographical authenticity. This study analyzed the proteins, 16 common amino acids, and 10 mineral elements (Ca, Cu, Fe, K, Mn, Mg, Na, Se, Sr, Zn) in samples from Fujian, Guangdong, Hubei, Jiangsu, [...] Read more.
The growing consumption of Volvariella volvacea has heightened concerns regarding its geographical authenticity. This study analyzed the proteins, 16 common amino acids, and 10 mineral elements (Ca, Cu, Fe, K, Mn, Mg, Na, Se, Sr, Zn) in samples from Fujian, Guangdong, Hubei, Jiangsu, Jiangxi, Shanghai, and Zhejiang, China, along with regional variations in stable isotope ratios. PCA and PLS-DA were applied for origin authentication. The results showed an average protein content of approximately 30 g/100 g (dry basis), with Guangdong samples being the highest. Amino acids exhibited significant regional differences, but the total essential amino acid and total amino acid contents did not. Mineral elements varied significantly by region, except for Cu and K. The Fujian, Hubei, Jiangxi, and Zhejiang samples exhibited significantly higher δ13C and δ15N values, while Shanghai samples had significantly higher δ2H and δ18O values. These differences enabled PCA to classify the samples into two groups: FHJZ (Fujian, Hubei, Jiangxi, Zhejiang) and GJS (Guangdong, Jiangsu, Shanghai). The PLS-DA model achieved 93.60% accuracy in distinguishing these two groups. Pairwise accuracy within the GJS group exceeded 80%, whereas that within the FHJZ group requires further improvement. These findings support the feasibility of stable isotope analysis for authenticating the geographical origin of Volvariella volvacea. Full article
(This article belongs to the Section Food Analytical Methods)
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17 pages, 3844 KiB  
Article
Comprehensive Characterization (Chromatography, Spectroscopy, Isotopic, and Digital Color Image) of Tequila 100% Agave Cristalino as Evidence of the Preservation of the Characteristics of Its Aging Process
by Walter M. Warren-Vega, Rocío Fonseca-Aguiñaga, Arantza Villa-González, Camila S. Gómez-Navarro and Luis A. Romero-Cano
Beverages 2025, 11(2), 42; https://doi.org/10.3390/beverages11020042 - 20 Mar 2025
Viewed by 383
Abstract
To obtain fundamental information on the Tequila 100% agave Cristalino commercial samples were characterized in their different classes. For this purpose, 12 samples were chosen, defined as: G1 (aged; n = 3, or extra-aged; n = 3) and G2 (aged-Cristalino; n [...] Read more.
To obtain fundamental information on the Tequila 100% agave Cristalino commercial samples were characterized in their different classes. For this purpose, 12 samples were chosen, defined as: G1 (aged; n = 3, or extra-aged; n = 3) and G2 (aged-Cristalino; n = 3 or extra-aged-Cristalino; n = 3). Analytical characterization was performed on these beverages, consisting of isotope ratio mass spectrometry, gas and liquid chromatography, UV-Vis spectroscopy, and color using digital image processing. The results corroborate that the chromatographic characterization (mg/100 mL A.A.)—higher alcohols (299.53 ± 46.56), methanol (212.02 ± 32.28), esters (26.02 ± 4.60), aldehydes (8.93 ± 4.61), and furfural (1.02 ± 0.56)—and isotopic characterization—δ13CVPDB = −13.02 ± 0.35 ‰ and δ18OVSMOW = 21.31 ± 1.33 ‰—do not present statistically significant differences (p > 0.05) between groups. From these techniques, it was possible to reinforce that isotopic ratios can provide information about that the ethanol of these alcoholic beverages come from Agave tequilana Weber blue variety and it is not affected in the filtration process. Based on the UV-Vis analysis, I280 and I365 were obtained, which were related to the presence of polyphenols and flavonoids—expressed as mg quercetin equivalents/L—only found in group 1. Due to the presence of flavonoids in aged beverages, the oxidation process results in the formation of an amber color, which can be measured by an RGB color model; therefore, the analysis shows that there is a statistically significant difference (p < 0.05) between groups. It can be concluded that Tequila 100% agave Cristalino is a Tequila 100% agave aged or extra-aged without color in which its chromatographic and isotopic profile is not affected. Full article
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28 pages, 11310 KiB  
Article
In Situ Geochemical and Sulfur Isotopic Composition of Pyrites from the Jiepailing Tin–Beryllium Polymetallic Deposit, Southern Hunan Province, China: Implications for Ore-Forming Processes
by Gao-Feng Du, Xiang-Ying Ling, Dan Wang, Wei-Jian Zhou, Liu Yang, You-Yue Lu and Zun-Zun Zhang
Minerals 2025, 15(3), 312; https://doi.org/10.3390/min15030312 - 18 Mar 2025
Viewed by 360
Abstract
The Jiepailing deposit in southern Hunan is a typical large to super-large polymetallic tin deposit enriched in beryllium and other rare metals. To enhance the understanding of the mineralization processes of the Jiepailing deposit, detailed mineralogical, in situ geochemical, and sulfur isotopic analyses [...] Read more.
The Jiepailing deposit in southern Hunan is a typical large to super-large polymetallic tin deposit enriched in beryllium and other rare metals. To enhance the understanding of the mineralization processes of the Jiepailing deposit, detailed mineralogical, in situ geochemical, and sulfur isotopic analyses were conducted on pyrite closely associated with tin–polymetallic mineralization. Five types of pyrite have been identified in the deposit: (1) euhedral to subhedral medium- to coarse-grained pyrite (PyI) in tungsten–tin ore; anhedral fine-grained pyrite (PyII) in tin polymetallic–fluorite ore; anhedral fine-grained or aggregate pyrite (PyIII) in lead–zinc ore; euhedral to subhedral coarse-grained pyrite (PyIV) in beryllium–fluorite mineralization; and subhedral to anhedral fine-grained pyrite (PyV) in carbonate veinlets developed in the wall rock. Backscattered electron imaging indicates consistent structural features across the five types of pyrite. In situ trace element analysis reveals differences in trace element concentrations among the pyrite types. PyI is relatively enriched in Sn, Cu, and Co. In contrast, PyIII is enriched in Pb, Zn, Sn, and Ti, while PyIV and PyV are enriched in Ag and Sb. PyI has a Co/Ni ratio more than 1, while the Co/Ni ratios in the other four types of pyrite are less than 1. LA-MC-ICP-MS in situ sulfur isotope analysis shows δ34S values ranging from 2.5‰ to 5.8‰ (average 4.3‰, PyI), 2.5‰ to 5.8‰ (average 4.3‰, PyII), −7.6‰ to 9.5‰ (average 3.9‰, PyIII), −3.7‰ to 10.6‰ (average 3.6‰, PyIV), and 6.8‰ to 14.1‰ (average 9.2‰, PyV). Based on previous studies, regional geological background, deposit characteristics, and the in situ trace element and sulfur isotope compositions of pyrite, it is inferred that the various ore bodies in the Jiepailing deposit are products of Late Cretaceous magmatic–hydrothermal activity. The early ore-forming fluid originated from magmatic sources and during the migration into the wall rock and shallow formations, mixed with fluids primarily derived from atmospheric precipitation. Temperature, pressure, and composition changed of the ore-forming fluid which carried a large amount of substances, leading to tungsten–tin, tin polymetallic–fluorite, lead–zinc, and beryllium–fluorite mineralization, followed by carbonation during the late-stage mineralization. Full article
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22 pages, 1734 KiB  
Article
Innovative Tools for Nitrogen Fertilization Traceability in Organic Farming Products: A Fennel Case Study
by Francesco Montemurro, Mariangela Diacono, Angelo Fiore, Luana Bontempo, Alberto Roncone, Margherita Amenta, Gabriele Ballistreri, Nicolina Timpanaro, Biagio Torrisi and Simona Fabroni
Horticulturae 2025, 11(3), 329; https://doi.org/10.3390/horticulturae11030329 - 17 Mar 2025
Viewed by 229
Abstract
Food fraud is a matter of great interest, particularly when organic productions are involved. Therefore, policymakers and institutions are asked to introduce new effective official control methods, not only based on documentary compliance to EU regulations. Lately, an integrated approach based on the [...] Read more.
Food fraud is a matter of great interest, particularly when organic productions are involved. Therefore, policymakers and institutions are asked to introduce new effective official control methods, not only based on documentary compliance to EU regulations. Lately, an integrated approach based on the use of isotopic, chemical and biological data treated by chemometrics has been suggested to authenticate organic products. The present research aims to validate the beforementioned integrated approach for the reliable classification of organically and conventionally grown fennel productions obtained by applying different treatments at diverse percentages of mineral fertilizers. Moreover, to the best of our knowledge, for the first time, an N-fixing plant (alfalfa), as an agroecological service crop in intercropping fennel, was introduced. Physicochemical parameters (fresh weight, total soluble solids, total acidity, consistency, Commission Internationale de l’Eclairage (CIE) lightness (L*), green-red (a*), blue-yellow (b*) color components), total phenolic content, in vitro antioxidant activity, total and inorganic N, and stable isotope ratios (15N/14N, 13C/12C, and 34S/32S) analyses were performed over a two-year field trial and further multivariate discriminant analysis was performed. The physicochemical parameters were not affected by the differential growing practice while antioxidant activity showed higher values in the organic treatments. The conventional treatments increased the NO3 values over 440% compared to the organic ones and the lowest values were found when alfalfa was used for intercropping. δ(15N) of fennel, δ(34S) of fennel and δ(15N) of leaves showed great discriminatory potential, with respect to the applied agronomic practice. However, these parameters alone were not sufficient as biomarkers for differentiating cultivation methods. Instead, the proposed innovative tool demonstrated that only a comprehensive multivariate approach was able to achieve a correct classification of grouped cases. Furthermore, the discrimination between organic and conventional horticultural products showed feasible results, even when N-fixing plants were incorporated in organic practice, thus avoiding misinterpretations solely based on the isotopic N fingerprint. These promising findings highlight the potential of this method and suggest that further research should extend its application to other horticultural crops to confirm and expand upon the current results. Full article
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18 pages, 1946 KiB  
Article
Stable Water Isotopes Across Marsh, River, and Lake Environments in the Zoige Alpine Wetland on the Tibetan Plateau
by Yangying Zhan, Chunyi Li, Yu Ning, Guichun Rong, You Zhou, Kexin Liu, Junxuan Li and Haoyang Wang
Water 2025, 17(6), 820; https://doi.org/10.3390/w17060820 - 12 Mar 2025
Viewed by 435
Abstract
Water isotope studies in alpine wetlands have revealed the dynamic characteristics of the hydrological cycle and evapotranspiration processes in the Zoige region through hydrogen and oxygen isotope ratios. However, the hydrological continuity between marshes, rivers, and lakes in wetlands is relatively understudied. The [...] Read more.
Water isotope studies in alpine wetlands have revealed the dynamic characteristics of the hydrological cycle and evapotranspiration processes in the Zoige region through hydrogen and oxygen isotope ratios. However, the hydrological continuity between marshes, rivers, and lakes in wetlands is relatively understudied. The study found that the Zoige Alpine Wetland local meteoric water line (LMWL) is δD = 8.33δ18O + 14.52 (R2 = 0.92) by using linear regression analysis to confirm the Craig temperature effect equation backwards. Comparison with the global and Chinese LMWLs revealed that the slope of the Zoige LMWL is significantly higher than those of the global and Chinese LMWLs, indicating that the oceanic warm and humid airflow and the southwest monsoon significantly influence this region. The δ18O ranges of rivers, lakes, and marshes in the Zoige wetland were −12.86‰ to −2.02‰, −12.9‰ to −2.22‰, and −15.47‰ to −7.07‰, respectively. In terms of δD, marshes had the lowest δD values, with a mean value of −89.58‰, while rivers and lakes had close δD values of about −72‰. Rivers had the most dramatic variation in d-excess values, ranging from −34.16‰ to 3.68‰, while marshes and lakes had more concentrated d-excess values, with particularly negative values in marshes. Regression analysis yielded a trend line of δD = 5.41δ18O − 29.57 for evaporation from the water bodies, further demonstrating the importance of evaporation effects in this region. By using the Rayleigh fractionation model and estimating the climatic conditions, we found that the lake water had the highest evaporation intensity (41%). Those of the river and marsh water were 40% and 36%, respectively. The results of this study provide new scientific insights into the hydrological connectivity, evaporation processes, and water source characteristics in the Zoige wetland. Future studies can shed more light on how climate change affects wetland hydrological systems and how they change over time and space. This will help to manage water resources in the region and protect the environment. Full article
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25 pages, 11638 KiB  
Article
Geochemical Study of Trace Elements and In Situ S–Pb Isotopes of the Sachakou Pb–Zn Deposit in the Aksai Chin Region, Xinjiang
by Xiaojian Zhao, Nuo Li, Tingbin Fan, Jing Sun, Qinglin Sui, Huishan Zhang, Zhouping Guo, Jianatiguli Wusiman, Kai Weng and Yanjing Chen
Minerals 2025, 15(3), 271; https://doi.org/10.3390/min15030271 - 6 Mar 2025
Viewed by 540
Abstract
The sulfide Pb–Zn deposits in the Aksai Chin region of Xinjiang have long been subject to debate regarding their genetic classification due to the unclear origin of the ore-forming components. This study focuses on the Sachakou Pb–Zn deposit, the most representative deposit in [...] Read more.
The sulfide Pb–Zn deposits in the Aksai Chin region of Xinjiang have long been subject to debate regarding their genetic classification due to the unclear origin of the ore-forming components. This study focuses on the Sachakou Pb–Zn deposit, the most representative deposit in the region, and integrates field investigations, petrographic observations, in situ LA-ICP-MS trace element analysis, and in situ S–Pb isotope analysis. The deposit is hosted within the siliceous rock and silicified limestone of the Lower Jurassic Bagongbulansha Formation, with ore bodies controlled by structural and stratigraphic factors. Three mineralization stages have been identified in the Sachakou deposit: a red–brown sphalerite mineralization stage (S1), a light-brown sphalerite stage (S2), and a galena mineralization stage (S3). The trace elements in sphalerite indicate that the mineralization process is unrelated to magmatic activity. The mineralization temperature, determined using a GGIMFis geothermometer, ranges from 294 °C to 121 °C. The δ34SV-CDT values of sulfides range from −4.93‰ to 1.24‰, suggesting that the Jurassic gypsum layer served as the sulfur source. The lead isotope ratios of 206Pb/204Pb range from 18.308 to 18.395, of 207Pb/204Pb—from 15.669 to 15.731, and of 208Pb/204Pb—from 38.595 to 38.776, indicating that the ore-forming metals were predominantly sourced from the upper crust. Based on geological and geochemical characteristics, the Sachakou Pb–Zn deposit is classified as a sedimentary-hosted epizonogenic hydrothermal deposit. Full article
(This article belongs to the Special Issue Genesis and Evolution of Pb-Zn-Ag Polymetallic Deposits: 2nd Edition)
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23 pages, 6275 KiB  
Article
The Evolution and Drivers of Hydrochemistry in Nam Co Lake, the Third Largest Lake on the Tibetan Plateau, over the Last 20 Years
by Wenhao Ren, Yanyan Gao, Hui Qian, Wengang Qu, Xiaoxin Shi, Yaoming Ma, Zhongbo Su and Weiqiang Ma
Sustainability 2025, 17(5), 2180; https://doi.org/10.3390/su17052180 - 3 Mar 2025
Viewed by 539
Abstract
The Tibetan Plateau, a critical regulator of the global water cycle and climate system, represents a highly sensitive region to environmental changes, with significant implications for sustainable development. This study focuses on Nam Co Lake, the third largest lake on the Tibetan Plateau, [...] Read more.
The Tibetan Plateau, a critical regulator of the global water cycle and climate system, represents a highly sensitive region to environmental changes, with significant implications for sustainable development. This study focuses on Nam Co Lake, the third largest lake on the Tibetan Plateau, and investigates the hydrochemical evolution of the lake and the driving mechanisms in regard to the lake–river–groundwater system within the Nam Co Basin over the last 20 years. Our findings provide critical insights for sustainable water resource management in regard to fragile alpine lake ecosystems. The hydrochemical analyses revealed distinct temporal patterns in the total dissolved solids, showing an increasing trend during the 2000s, followed by a decrease in the 2010s. Piper diagrams demonstrated a gradual change in the anion composition from the Cl type to the HCO3 type over the study period. The ion ratio analyses identified rock weathering (particularly silicate, halite, sulfate, and carbonate weathering), ion exchange, and evaporation processes as primary controlling processes, with notable differences between water bodies: while all four weathering processes contributed to the lake’s water chemistry, only halite and carbonate weathering influenced river and groundwater compositions. The comparative analysis revealed more pronounced ion exchange processes in lake water than in river and groundwater systems. Climate change impacts were manifested through two primary mechanisms: (1) enhanced evaporation, leading to elevated ion concentrations and isotopic enrichment; and (2) temperature-related effects on the water chemistry through increased dilution from precipitation and glacial meltwater. Understanding these mechanisms is essential for developing adaptive strategies to maintain water security and ecosystem sustainability. The relationships established between climate drivers and hydrochemical responses provide a scientific basis for predicting future changes and informing sustainable management practices for inland lake systems across the Tibetan Plateau. Full article
(This article belongs to the Section Environmental Sustainability and Applications)
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14 pages, 3102 KiB  
Article
Lead Isotope Ratio Measurements for Source Identification Using Samples from the UK Heavy Metals Air Quality Monitoring Network
by Emma C. Braysher, Jody H. L. Cheong, David M. Butterfield, Andrew S. Brown and Richard J. C. Brown
Atmosphere 2025, 16(3), 283; https://doi.org/10.3390/atmos16030283 - 27 Feb 2025
Viewed by 379
Abstract
Lead isotope ratios vary depending on the origin of the lead, meaning that characteristic isotopic signatures can be used for source identification in environmental samples. Lead in ambient particulate matter was collected and analysed at 23 monitoring stations as part of the UK [...] Read more.
Lead isotope ratios vary depending on the origin of the lead, meaning that characteristic isotopic signatures can be used for source identification in environmental samples. Lead in ambient particulate matter was collected and analysed at 23 monitoring stations as part of the UK heavy metals air quality monitoring network to assess compliance with legislative limit values for allowable concentrations of lead in air. For the first time on a nationwide UK basis, isotopic analysis of lead was carried out on these samples to gain further information about the origin of the lead and the sources influencing measured concentrations at each of the monitoring stations. These measurements were undertaken with the novel application of ICP–MS/MS for high throughput analysis of over 200 samples from 23 sites across the UK. Values for 207Pb/206Pb ranged from 0.864 to 0.910 with an average standard error of 0.68%, while 208Pb/206Pb values ranged from 2.08 to 2.187 with an average standard error of 0.84%. The dataset was used to draw conclusions as to the main sources of pollution contributing to each site and has demonstrated the utility of ICP–MS/MS as a fit-for-purpose analytical method for the high throughput of a large number of samples in complex matrices. It was possible to identify different source types at the monitoring stations based on the lead isotope signature observed. Comparison with literature values showed clear links with traffic emissions at roadside sites and leaded petrol at a site near an airfield where small aircraft still use this type of fuel. Full article
(This article belongs to the Special Issue Atmospheric Pollutants: Monitoring and Observation)
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22 pages, 4255 KiB  
Article
Characterization of Intra-Quarry Variability in Pentelic Marble Using Stable Isotopes: A Case Study of the Parthenon
by Scott Pike
Minerals 2025, 15(3), 231; https://doi.org/10.3390/min15030231 - 26 Feb 2025
Viewed by 396
Abstract
This study presents a systematic analysis of stable isotopes (δ13C and δ18O) in Pentelic marble from the ancient quarries of Mount Pentelikon, Greece. A total of 610 samples were collected from 83 quarry pits, including all identified ancient extraction [...] Read more.
This study presents a systematic analysis of stable isotopes (δ13C and δ18O) in Pentelic marble from the ancient quarries of Mount Pentelikon, Greece. A total of 610 samples were collected from 83 quarry pits, including all identified ancient extraction sites, to build a comprehensive reference database. Of those, stable isotope ratios of carbon and oxygen were measured for 384 samples. The results reveal significant variability in stable isotope values across different quarry regions, challenging the assumption of isotopic homogeneity in Pentelic marble. Notably, distinct δ13C and δ18O patterns allow differentiation between quarry areas and specific extraction zones. These findings provide a more refined isotopic framework for provenance studies of ancient artifacts. Application of the new database suggests that marble for the Parthenon’s West Pediment was sourced from the northern upslope quarries in Aspra Marmara, whereas structural elements of the Parthenon were extracted from the lower Spilia Divail quarry, as well as other pits across the ancient quarry zone. The results demonstrate that multiple quarry pits from both the lower slope and upper slope quarries were exploited for the construction of the Parthenon. This research highlights the benefits of extensive sampling and stable isotope analysis in identifying quarry sources, emphasizing the value of undertaking detailed and thorough field surveys and sampling programs to gain new perspectives into ancient resource use. Full article
(This article belongs to the Special Issue Provenance Analyses of Ancient Stones Using Scientific Methods)
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32 pages, 6811 KiB  
Article
Probing Petroleum Sources Using Geochemistry, Multivariate Analysis, and Basin Modeling: A Case Study from the Dibei Gas Field in the Northern Kuqa Foreland Basin, NW China
by Xinzhuo Wei, Keyu Liu, Xianzhang Yang, Jianliang Liu, Lu Zhou and Xiujian Ding
Appl. Sci. 2025, 15(5), 2425; https://doi.org/10.3390/app15052425 - 24 Feb 2025
Viewed by 322
Abstract
The Dibei Gas Field, located in the northern Kuqa Foreland Basin, Tarim Basin, western China, is one of the most important condensate gas-producing areas in China, with over one trillion cubic feet of gas reserves discovered in the Jurassic terrestrial reservoirs. However, further [...] Read more.
The Dibei Gas Field, located in the northern Kuqa Foreland Basin, Tarim Basin, western China, is one of the most important condensate gas-producing areas in China, with over one trillion cubic feet of gas reserves discovered in the Jurassic terrestrial reservoirs. However, further hydrocarbon exploration and development in the area is hampered by uncertainties on the petroleum sources. A robust oil–source and gas-source correlation analysis was carried out in the Dibei area to enhance our understanding of the gas accumulation potential. An integrated molecular geochemical analysis, multivariate analysis, and basin modeling were conducted to investigate source rocks, inclusion oils, reservoir oils, and gas from the Dibei area. Two types of source rocks have been identified in the Dibei area: a Jurassic coaly source rock and a Triassic lacustrine source rock based on multivariate analysis. The compositions of the n-alkanes, steranes, and terpanes and the carbon isotope ratios of individual n-alkanes in the inclusion oil extracts and reservoir oils from Jurassic Yangxia and Ahe reservoirs show distinct differences when compared with the two types of source extracts. Multiple oil sources are revealed in the Dibei area, with various degrees of mixing between reservoir oil (present) and inclusion oil (paleo), reflecting evolving oil sources. Basin modeling shows that during the late Himalayan orogeny, the Jurassic strata in the Dibei area experienced a rapid burial within ~20 Ma, with the oil generation window of the source rocks expanding greatly. This caused the shallowly buried Jurassic source rocks to enter the oil generation window, resulting in the occurrence of two oil sources for the inclusion oils and reservoir oils, and an increasing degree of mixing over time. Our finding confirms that the accumulated condensate gas in the Dibei area is mainly derived from the Jurassic source rocks. This allows the extent of prospective exploration to be better defined. Full article
(This article belongs to the Section Energy Science and Technology)
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16 pages, 3429 KiB  
Article
Beef Traceability Between China and Argentina Based on Various Machine Learning Models
by Xiaomeng Xiang, Chaomin Zhao, Runhe Zhang, Jing Zeng, Liangzi Wang, Shuran Zhang, Diego Cristos, Bing Liu, Siyan Xu and Xionghai Yi
Molecules 2025, 30(4), 880; https://doi.org/10.3390/molecules30040880 - 14 Feb 2025
Viewed by 595
Abstract
Beef, as a nutrient-rich food, is widely favored by consumers. The production region significantly influences the nutritional value and quality of beef. However, current methods for tracing the origin of beef are still under development, necessitating effective approaches to ensure food safety and [...] Read more.
Beef, as a nutrient-rich food, is widely favored by consumers. The production region significantly influences the nutritional value and quality of beef. However, current methods for tracing the origin of beef are still under development, necessitating effective approaches to ensure food safety and meet consumer demand for high-quality beef. This study aims to establish a classification model for beef origin prediction by analyzing elemental content and stable isotopes in beef samples from two countries. The concentrations of elements in beef were analyzed using ICP-MS and ICP-OES, while the stable carbon isotope ratio was determined using EA-IRMS. Machine learning algorithms were employed to construct classification prediction models. A total of 83 beef samples were analyzed for the concentrations of 52 elements and the stable carbon isotope ratio. The classification accuracy of the PLS-DA model built on these results was 98.8%, while the prediction accuracy was 94.12% for the convolutional neural network (CNN) and 82.35% for the Random Forest algorithm. The PLS-DA model demonstrated higher classification accuracy compared to CNN and Random Forest, with an explanatory power (R2) of 0.924 and predictive ability (Q2) of 0.787. Combining the analysis of 52 elements and the stable carbon isotope ratio with machine learning algorithms enables effective tracing and origin prediction of beef from different regions. Key factors influencing beef origin were identified as Fe, Cs, As, δ13C, Co, V, Sc, Rb, and Ru. Full article
(This article belongs to the Special Issue Applications of Spectroscopic Techniques in Food Sample Analysis)
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27 pages, 6166 KiB  
Article
Farmland Afforestation by Poplar Shelterbelts Increased Soil Inorganic Carbon but Showed Ambiguous Effects on Soil Organic Carbon as Revealed by Carbon Isotopic Composition: Inter-Fraction and Inter-Site Differences in Northern China
by Qianru Ji, Huan Jiang, Zhihong Xu, Meina Zhu, Shaoqing Zhang, Huimei Wang, Zhonghua Tang, Qiong Wang and Wenjie Wang
Forests 2025, 16(2), 328; https://doi.org/10.3390/f16020328 - 13 Feb 2025
Viewed by 559
Abstract
Afforestation has been considered to be the cost-effective way to sequestrate carbon (C) dioxide from the atmosphere in the soils, while concurrent responses of soil inorganic C (SIC) and soil organic C (SOC), and their turnover are still not well-defined. During the C [...] Read more.
Afforestation has been considered to be the cost-effective way to sequestrate carbon (C) dioxide from the atmosphere in the soils, while concurrent responses of soil inorganic C (SIC) and soil organic C (SOC), and their turnover are still not well-defined. During the C cycle, inorganic C is enriched in heavy isotopes (13C), while organic C, due to photosynthetic fractionation, is enriched in light isotopes (12C). This leads to distinct C isotope fractionation in terrestrial ecosystems. In this study, 72 paired soils (0–20 cm) from poplar shelterbelts and adjacent farmland sites were collected in six regions (Zhaozhou, Fuyu, Dumeng, Zhaodong, Lanling, and Mingshui) of northeastern China. Five soil fractions of dissolved organic C (DOC), particulate organic matter (POM), sand and stable aggregates (S + A), silt and clay (S + C), and resistant SOC (rSOC) and bulk soils were used in C content assay and the natural δ13C determination. The results showed that, compared with SOC, poplar shelterbelts resulted in SIC accrual in the soils across all six sites; however, only half of the six sites showed SOC accrual, indicating an ambiguous effect of afforestation on SOC. The natural δ13C method could identify the SOC turnover owing to the C isotopic discrimination. The δ13C–SOC-derived turnover ratio was 23%. When SIC was included in the δ13C measurement, bulk soils and four soil fractions (S + C, S + A, rSOC, DOC) showed a 2%–10% lower turnover percentage than the δ13C–SOC-derived turnover ratios. The SIC inclusion resulted in the dependency of δ13C–TC (TC = SIC + SOC) values on SOC (negative, R2: 0.21–0.44) and SIC content (positive, R2: 0.39–0.63). By contrast, when SIC was excluded, the δ13C–SOC values were independent of them (R2 < 0.18). Redundancy ordination analysis manifested that more SOC in the soils, together with more POM and farming uses would be accompanied with the lower δ13C values. Moreover, forest characteristics (e.g., age and density) and farmland backgrounds (e.g., crop history and distance between forest and farmland) could explain differences in δ13C-related features. Our results highlighted that SIC in natural δ13C determination underestimated the C turnover ratio in general. However, SIC storage should be included in the soil C sequestration evaluation owing to a general SIC accrual pattern across regions when compared with those of SOC. Full article
(This article belongs to the Special Issue Monitoring and Modelling of Soil Properties in Forest Ecosystems)
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18 pages, 2383 KiB  
Article
Authentic Aroma and Compound-Specific Isotope Ratios (δ13C, δ2H) Profiles of Vanilla Pods (V. planifolia and V. tahitensis)
by Long Chen, Purna Kumar Khatri, Mauro Paolini, Tiziana Nardin, Alberto Roncone, Roberto Larcher, Luca Ziller and Luana Bontempo
Molecules 2025, 30(4), 825; https://doi.org/10.3390/molecules30040825 - 11 Feb 2025
Viewed by 753
Abstract
Stable isotope ratio analysis of carbon (δ13C) and hydrogen (δ2H) in vanillin has become a valuable tool for differentiating natural vanilla from synthetic or biosynthetic alternatives and for tracing its geographical origins. However, increasingly sophisticated fraud techniques [...] Read more.
Stable isotope ratio analysis of carbon (δ13C) and hydrogen (δ2H) in vanillin has become a valuable tool for differentiating natural vanilla from synthetic or biosynthetic alternatives and for tracing its geographical origins. However, increasingly sophisticated fraud techniques necessitate ongoing refinement of analytical methods to ensure accurate detection. This study advanced the field by investigating minor volatile organic compounds as potential biomarkers for identifying botanical and geographical origins of vanilla products. Vanilla pods from the two main vanilla species, V. planifolia and V. tahitensis, were investigated using GC-MS/MS to analyze their aromatic profile and GC-C/Py-IRMS to determine compound-specific isotope ratios, providing, for the first time, detailed and authentic isotopic and aromatic profiles. Additionally, the potential natural presence of ethyl vanillin and its corresponding glucoside precursors—molecules commonly used as synthetic vanilla-scented fragrance agents in various foods and industrial products—was explored using UHPLC-HRMS. These findings contribute to robust methods for verifying vanilla authenticity, addressing flavor complexity and isotopic composition, and enhancing the detection of adulteration in vanilla-flavored products. Full article
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