Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Article Types

Countries / Regions

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Search Results (1,624)

Search Parameters:
Keywords = water isotopes

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
20 pages, 3033 KiB  
Review
Recharge Sources and Flow Pathways of Karst Groundwater in the Yuquan Mountain Spring Catchment Area, Beijing: A Synthesis Based on Isotope, Tracers, and Geophysical Evidence
by Yuejia Sun, Liheng Wang, Qian Zhang and Yanhui Dong
Water 2025, 17(15), 2292; https://doi.org/10.3390/w17152292 - 1 Aug 2025
Viewed by 190
Abstract
Karst groundwater systems are critical to water supply and ecological sustainability in northern China, yet their heterogeneity poses challenges for flow characterization. The Yuquan Mountain (YM) Spring, historically a major karst spring in western Beijing, has experienced persistent drying, raising concerns about its [...] Read more.
Karst groundwater systems are critical to water supply and ecological sustainability in northern China, yet their heterogeneity poses challenges for flow characterization. The Yuquan Mountain (YM) Spring, historically a major karst spring in western Beijing, has experienced persistent drying, raising concerns about its recharge and flow mechanisms. This study integrates published isotope data, spatial distributions of Na+ and Cl as hydrochemical tracers, groundwater age estimates, and geophysical survey results to assess the recharge sources and flow pathways within the YM Spring catchment area. The analysis identifies two major recharge zones: the Tanzhesi area, primarily recharged by direct infiltration of precipitation through exposed carbonate rocks, and the Junzhuang area, which receives mixed recharge from rainfall and Yongding River seepage. Three potential flow pathways are proposed, including shallow flow along faults and strata, and a deeper, speculative route through the Jiulongshan-Xiangyu syncline. The synthesis of multiple lines of evidence leads to a refined conceptual model that illustrates how geological structures govern recharge, flow, and discharge processes in this karst system. These findings not only enhance the understanding of subsurface hydrodynamics in complex geological settings but also provide a scientific basis for future spring restoration planning and groundwater management strategies in the regions. Full article
Show Figures

Figure 1

11 pages, 711 KiB  
Article
Cadmium Accumulation and Regulation in the Freshwater Mussel Anodonta woodiana
by Xiubao Chen, Chao Song, Jiazhen Jiang, Tao Jiang, Junren Xue, Ibrahim Bah, Mengying Gu, Meiyi Wang and Shunlong Meng
Toxics 2025, 13(8), 646; https://doi.org/10.3390/toxics13080646 - 30 Jul 2025
Viewed by 151
Abstract
Cadmium (Cd) pollution poses a serious threat to freshwater ecosystems. The freshwater mussel Anodonta woodiana is increasingly used as a bioindicator for monitoring Cd pollution in aquatic environments. However, the primary routes of Cd accumulation in A. woodiana remain unclear, and the molecular [...] Read more.
Cadmium (Cd) pollution poses a serious threat to freshwater ecosystems. The freshwater mussel Anodonta woodiana is increasingly used as a bioindicator for monitoring Cd pollution in aquatic environments. However, the primary routes of Cd accumulation in A. woodiana remain unclear, and the molecular regulatory mechanisms underlying Cd accumulation are poorly understood. To address these gaps, this study employed a novel stable isotope dual-tracer technique to trace Cd from water (waterborne 112Cd) and the green alga Chlorella vulgaris (dietary 113Cd) during the simultaneous exposure experiment. Comparative transcriptomic analysis was then conducted to characterize molecular responses in A. woodiana following Cd exposure. The results showed that although newly accumulated 112Cd and 113Cd increased with exposure concentration and duration, the relative importance of 112Cd (91.6 ± 2.8%) was significantly higher than that of 113Cd (8.4 ± 2.8%) (p < 0.05). Cd exposure induced differentially expressed genes primarily enriched in the metabolic processes, cellular processes, and/or the ubiquitin-mediated proteolysis pathway. Within the ubiquitin-mediated proteolysis pathway, TRIP12 (E3 ubiquitin-protein ligase TRIP12) and Cul5 (cullin-5) were significantly upregulated. The findings will provide critical insights for interpreting Cd biomonitoring data in freshwater environments using mussels as bioindicators. Full article
(This article belongs to the Special Issue The Impact of Heavy Metals on Aquatic Ecosystems)
Show Figures

Figure 1

24 pages, 5270 KiB  
Article
Ecophysiological Keys to the Success of a Native-Expansive Mediterranean Species in Threatened Coastal Dune Habitats
by Mario Fernández-Martínez, Carmen Jiménez-Carrasco, Mari Cruz Díaz Barradas, Juan B. Gallego-Fernández and María Zunzunegui
Plants 2025, 14(15), 2342; https://doi.org/10.3390/plants14152342 - 29 Jul 2025
Viewed by 190
Abstract
Range-expanding species, or neonatives, are native plants that spread beyond their original range due to recent climate or human-induced environmental changes. Retama monosperma was initially planted near the Guadalquivir estuary for dune stabilisation. However, changes in the sedimentary regime and animal-mediated dispersal have [...] Read more.
Range-expanding species, or neonatives, are native plants that spread beyond their original range due to recent climate or human-induced environmental changes. Retama monosperma was initially planted near the Guadalquivir estuary for dune stabilisation. However, changes in the sedimentary regime and animal-mediated dispersal have facilitated its exponential expansion, threatening endemic species and critical dune habitats. The main objective of this study was to identify the key functional traits that may explain the competitive advantage and rapid spread of R. monosperma in coastal dune ecosystems. We compared its seasonal responses with those of three co-occurring woody species, two native (Juniperus phoenicea and J. macrocarpa) and one naturalised (Pinus pinea), at two sites differing in groundwater availability within a coastal dune area (Doñana National Park, Spain). We measured water relations, leaf traits, stomatal conductance, photochemical efficiency, stable isotopes, and shoot elongation in 12 individuals per species. Repeated-measures ANOVA showed significant effects of species and species × season interaction for relative water content, shoot elongation, effective photochemical efficiency, and stable isotopes. R. monosperma showed significantly higher shoot elongation, relative water content, and photochemical efficiency in summer compared with the other species. Stable isotope data confirmed its nitrogen-fixing capacity. This characteristic, along with the higher seasonal plasticity, contributes to its competitive advantage. Given the ecological fragility of coastal dunes, understanding the functional traits favouring the success of neonatives such as R. monosperma is essential for biodiversity conservation and ecosystem management. Full article
Show Figures

Figure 1

22 pages, 11338 KiB  
Article
Genesis of Clastic Reservoirs in the First Member of Yaojia Formation, Northern Songliao Basin
by Junhui Li, Qiang Zheng, Yu Cai, Huaye Liu, Tianxin Hu and Haiguang Wu
Minerals 2025, 15(8), 795; https://doi.org/10.3390/min15080795 - 29 Jul 2025
Viewed by 186
Abstract
This study focuses on the clastic reservoir in the first member of Yaojia Formation within Qijia-Gulong Sag, Songliao Basin. The results indicate that the reservoir in the study area develops within a shallow-water delta sedimentary system. The dominant sedimentary microfacies comprise underwater distributary [...] Read more.
This study focuses on the clastic reservoir in the first member of Yaojia Formation within Qijia-Gulong Sag, Songliao Basin. The results indicate that the reservoir in the study area develops within a shallow-water delta sedimentary system. The dominant sedimentary microfacies comprise underwater distributary channels, mouth bars, and sheet sands. Among these, the underwater distributary channel microfacies exhibits primary porosity ranging from 15.97% to 17.71%, showing the optimal reservoir quality, whereas the sheet sand microfacies has a porosity of only 7.45% to 12.08%, indicating inferior physical properties. During diagenesis, compaction notably decreases primary porosity via particle rearrangement and elastic deformation, while calcite cementation and quartz overgrowth further occlude pore throats. Although dissolution can generate secondary porosity (locally up to 40%), the precipitation of clay minerals tends to block pore throats, leading to “ineffective porosity” (permeability generally < 5 mD) and overall low-porosity and low-permeability characteristics. Carbon–oxygen isotope analysis reveals a deficiency in organic acid supply in the study area, restricting the intensity of dissolution alteration. Reservoir quality evolution is dominantly governed by the combined controls of sedimentary microfacies and diagenesis. This study emphasizes that, within shallow-water delta sedimentary settings, the material composition of sedimentary microfacies and the dynamic equilibrium of diagenetic processes jointly govern reservoir property variations. This insight provides critical theoretical support for understanding diagenetic evolution mechanisms in clastic reservoirs and enabling precise prediction of high-quality reservoir distribution. Full article
(This article belongs to the Section Mineral Exploration Methods and Applications)
Show Figures

Figure 1

21 pages, 4796 KiB  
Article
Hydrogeochemical Characteristics, Formation Mechanisms, and Groundwater Evaluation in the Central Dawen River Basin, Northern China
by Caiping Hu, Kangning Peng, Henghua Zhu, Sen Li, Peng Qin, Yanzhen Hu and Nan Wang
Water 2025, 17(15), 2238; https://doi.org/10.3390/w17152238 - 27 Jul 2025
Viewed by 327
Abstract
Rapid socio-economic development and the impact of human activities have exerted tremendous pressure on the groundwater system of the Dawen River Basin (DRB), the largest tributary in the middle and lower reaches of the Yellow River. Hydrochemical studies on the DRB have largely [...] Read more.
Rapid socio-economic development and the impact of human activities have exerted tremendous pressure on the groundwater system of the Dawen River Basin (DRB), the largest tributary in the middle and lower reaches of the Yellow River. Hydrochemical studies on the DRB have largely centered on the upstream Muwen River catchment and downstream Dongping Lake, with some focusing solely on karst groundwater. Basin-wide evaluations suggest good overall groundwater quality, but moderate to severe contamination is confined to the lower Dongping Lake area. The hydrogeologically complex mid-reach, where the Muwen and Chaiwen rivers merge, warrants specific focus. This region, adjacent to populous areas and industrial/agricultural zones, features diverse aquifer systems, necessitating a thorough analysis of its hydrochemistry and origins. This study presents an integrated hydrochemical, isotopic investigation and EWQI evaluation of groundwater quality and formation mechanisms within the multiple groundwater types of the central DRB. Central DRB groundwater has a pH of 7.5–8.2 (avg. 7.8) and TDSs at 450–2420 mg/L (avg. 1075.4 mg/L) and is mainly brackish, with Ca2+ as the primary cation (68.3% of total cations) and SO42− (33.6%) and NO3 (28.4%) as key anions. The Piper diagram reveals complex hydrochemical types, primarily HCO3·SO4-Ca and SO4·Cl-Ca. Isotopic analysis (δ2H, δ18O) confirms atmospheric precipitation as the principal recharge source, with pore water showing evaporative enrichment due to shallow depths. The Gibbs diagram and ion ratios demonstrate that hydrochemistry is primarily controlled by silicate and carbonate weathering (especially calcite dissolution), active cation exchange, and anthropogenic influences. EWQI assessment (avg. 156.2) indicates generally “good” overall quality but significant spatial variability. Pore water exhibits the highest exceedance rates (50% > Class III), driven by nitrate pollution from intensive vegetable cultivation in eastern areas (Xiyangzhuang–Liangzhuang) and sulfate contamination from gypsum mining (Guojialou–Nanxiyao). Karst water (26.7% > Class III) shows localized pollution belts (Huafeng–Dongzhuang) linked to coal mining and industrial discharges. Compared to basin-wide studies suggesting good quality in mid-upper reaches, this intensive mid-reach sampling identifies critical localized pollution zones within an overall low-EWQI background. The findings highlight the necessity for aquifer-specific and land-use-targeted groundwater protection strategies in this hydrogeologically complex region. Full article
(This article belongs to the Section Hydrogeology)
Show Figures

Figure 1

24 pages, 3436 KiB  
Article
Peculiarities of 222Radon and 238Uranium Behavior in Mineral Waters of Highland Terrains
by George Chelnokov, Vasilii Lavrushin, Natalya Kharitonova, Andrey Pavlov and Farid Salikhov
Water 2025, 17(15), 2211; https://doi.org/10.3390/w17152211 - 24 Jul 2025
Viewed by 192
Abstract
Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for 222Rn activity and 238U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to [...] Read more.
Mineral waters from two tectonically active mountain systems within the Alpine-Himalayan orogenic belt, the Pamir and the Greater Caucasus (Elbrus region), were analyzed for 222Rn activity and 238U concentrations to establish correlations with geological conditions, physicochemical characteristics of water, and to assess the potential health risk associated with 238U and 222Rn. It was found that in mineral waters of the Pamir, the concentrations of 238U (0.004–13.3 µg/L) and activity of 222Rn (8–130 Bq/L) are higher than in the Elbrus area: 0.04–3.74 µg/L and 6–33 Bq/L, respectively. Results indicate that uranium mobility in water is strongly influenced by T, pH, and Eh, but is less affected by the age of host rocks or springs′ elevation, whereas radon activity in waters depends on the age of rocks, spring elevation, 238U content, and values of δ18O and δ2H in water. This study reveals fundamental geological distinctions governing uranium and radon sources in the mineral waters of these regions. Isotopic evidence (222Rn and 3He/4He) demonstrates crustal radon sources prevail in Pamir, whereas the Elbrus system suggests mantle-derived components. The U concentrations do not exceed 30 µg/L, and most water samples (94%) showed 222Rn activities below 100 Bq/L, complying with the drinking water exposure limits recommended by the World Health Organization and European Union Directive. However, in intermountain depressions of the Pamirs, at low absolute elevations (~2300 m), radon concentrations in water can increase significantly, which requires special attention and study. Full article
Show Figures

Figure 1

17 pages, 4524 KiB  
Article
Growth and Water-Use Efficiency of European Beech and Turkey Oak at Low-Elevation Site
by Negar Rezaie, Ettore D’Andrea, Marco Ciolfi, Enrico Brugnoli and Silvia Portarena
Forests 2025, 16(8), 1210; https://doi.org/10.3390/f16081210 - 23 Jul 2025
Viewed by 754
Abstract
In Italy, beech and Turkey oak are among the most widespread tree species, thriving across various climatic zones. However, rising temperatures and prolonged droughts significantly affect their physiological performance and growth dynamics. To assess their long-term responses to climate change, mature beech and [...] Read more.
In Italy, beech and Turkey oak are among the most widespread tree species, thriving across various climatic zones. However, rising temperatures and prolonged droughts significantly affect their physiological performance and growth dynamics. To assess their long-term responses to climate change, mature beech and Turkey oak trees were studied in Central Italy at an elevation of 450 m. Using dendrochronological and stable isotope analyses (1981–2020), their growth patterns and physiological adaptations were evaluated. Beech exhibited a higher growth rate, with a basal area increment (BAI) of 17.1 ± 1.1 cm2 year−1, compared to Turkey oak, showing a BAI of 12.7 ± 0.96 cm2 year−1. Both species actively responded to increasing atmospheric CO2 levels. Additionally, spring and the previous summer’s climatic conditions played a key role in growth, while summer temperature and precipitation influenced carbon discrimination. For beech, correlations between BAI and iWUE (intrinsic water efficiency, defined as the ratio between photosynthesis and stomatal conductance) were initially weak and not statistically significant. However, the correlation became significant, strengthening steadily into the early 2000s, likely related to thinning of the beech trees. For Turkey oak, the correlation was already significant and strong from the beginning of the analysis period (1981), persisting until the late 1990s. Our findings suggest that both species actively adjust their iWUE in response to an increasing atmospheric CO2 concentration. However, while Turkey oak’s iWUE and BAI relationship remains unaffected by the likely thinning, beech benefits from reduced competition for light, nutrients, and water. Despite climate change’s impact on marginal populations, microclimatic conditions allow beech to outperform Turkey oak, a species typically better suited to drier climates. Full article
Show Figures

Figure 1

17 pages, 2126 KiB  
Article
Stable Carbon and Nitrogen Isotope Signatures in Three Pondweed Species—A Case Study of Rivers and Lakes in Northern Poland
by Zofia Wrosz, Krzysztof Banaś, Marek Merdalski and Eugeniusz Pronin
Plants 2025, 14(15), 2261; https://doi.org/10.3390/plants14152261 - 22 Jul 2025
Viewed by 194
Abstract
Aquatic plants, as sedentary lifestyle organisms that accumulate chemical substances from their surroundings, can serve as valuable indicators of long-term anthropogenic pressure. In Poland, water monitoring is limited both spatially and temporally, which hampers a comprehensive assessment of water quality. Since the implementation [...] Read more.
Aquatic plants, as sedentary lifestyle organisms that accumulate chemical substances from their surroundings, can serve as valuable indicators of long-term anthropogenic pressure. In Poland, water monitoring is limited both spatially and temporally, which hampers a comprehensive assessment of water quality. Since the implementation of the Water Framework Directive (WFD), biotic elements, including macrophytes, have played an increasingly important role in water monitoring. Moreover, running waters, due to their dynamic nature, are susceptible to episodic pollution inputs that may be difficult to detect during isolated, point-in-time sampling campaigns. The analysis of stable carbon (δ13C) and nitrogen (δ15N) isotope signatures in macrophytes enables the identification of elemental sources, including potential pollutants. Research conducted between 2008 and 2011 encompassed 38 sites along 15 rivers and 108 sites across 21 lakes in northern Poland. This study focused on the isotope signatures of three pondweed species: Stuckenia pectinata, Potamogeton perfoliatus, and Potamogeton crispus. The results revealed statistically significant differences in the δ13C and δ15N values of plant organic matter between river and lake environments. Higher δ15N values were observed in rivers, whereas higher δ13C values were recorded in lakes. Spearman correlation analysis showed a negative relationship between δ13C and δ15N, as well as correlations between δ15N and the concentrations of Ca2+ and HCO3. A positive correlation was also found between δ13C and dissolved oxygen levels. These findings confirm the utility of δ13C and, in particular, δ15N as indicators of anthropogenic eutrophication, including potentially domestic sewage input and its impact on aquatic ecosystems. Full article
Show Figures

Figure 1

21 pages, 8441 KiB  
Article
Upper Pleistocene Marine Levels of the Es Copinar–Es Estufadors (Formentera, Balearic Islands, West Mediterranean)
by Laura del Valle, Guillem X. Pons and Joan J. Fornós
Quaternary 2025, 8(3), 38; https://doi.org/10.3390/quat8030038 - 21 Jul 2025
Viewed by 376
Abstract
Late Pleistocene coastal deposits on the southeastern coast of Formentera (Es Ram–Es Estufadors) provide a high-resolution record of sea-level and climatic fluctuations associated with Marine Isotope Stage (MIS) 5. Three distinct beach levels (Sef-1, Sef-2, Sef-3) were identified, corresponding to substages MIS 5e, [...] Read more.
Late Pleistocene coastal deposits on the southeastern coast of Formentera (Es Ram–Es Estufadors) provide a high-resolution record of sea-level and climatic fluctuations associated with Marine Isotope Stage (MIS) 5. Three distinct beach levels (Sef-1, Sef-2, Sef-3) were identified, corresponding to substages MIS 5e, 5c, and possibly 5a, based on sedimentological features, fossil assemblages, and Optically Stimulated Luminescence (OSL) dating. The oldest beach level (Sef-1) is attributed to MIS 5e (ca. 128–116 ka) and is characterised by the widespread presence of thermophilic Senegalese fauna—including Thetystrombus latus, Conus ermineus, and Linatella caudata—which mark the onset of this interglacial phase and are associated with two peaks in relative sea-level highstand. A subsequent cooling event during MIS 5d is recorded by the development of thin palaeosols and the disappearance of these warm-water taxa. The second beach level (Sef-2) reflects renewed sea-level rise and warmer conditions during MIS 5c, with abundant macrofauna and red algae. The transition to MIS 5b (~97 ka) is marked by a significant sea-level drop (down to –60 m), cooler climate, and enhanced colluvial sedimentation linked to increased runoff and erosion. In total, 54 macrofaunal species were identified—16 from Sef-1 and 46 from Sef-2—highlighting ecological shifts across substages. These results improve our understanding of coastal response to sea-level oscillations and paleoenvironmental dynamics in the western Mediterranean during the Late Pleistocene. Full article
Show Figures

Figure 1

21 pages, 5158 KiB  
Article
Genesis of the Erentaolegai Silver Deposit, Inner Mongolia, Northeast China: Evidence from Fluid Inclusion and H-O-S Isotopes
by Yushan Zuo, Xintong Dong, Zhengxi Gao, Liwen Wu, Zhao Liu, Jiaqi Xu, Shanming Zhang and Wentian Mi
Minerals 2025, 15(7), 748; https://doi.org/10.3390/min15070748 - 17 Jul 2025
Viewed by 303
Abstract
The Erentaolegai silver deposit is located within the Derbugan metallogenic belt in the eastern segment of the Central Asia–Mongolia giant orogenic belt. The ore bodies are primarily hosted in the volcanic rocks of the Middle Jurassic Tamulangou Formation of the Mesozoic. The mineralization [...] Read more.
The Erentaolegai silver deposit is located within the Derbugan metallogenic belt in the eastern segment of the Central Asia–Mongolia giant orogenic belt. The ore bodies are primarily hosted in the volcanic rocks of the Middle Jurassic Tamulangou Formation of the Mesozoic. The mineralization process of the deposit is divided into three stages: Stage I: Pyrite–Quartz Stage; Stage II: Sulfide–Quartz Stage; Stage III: Quartz–Manganese Carbonate Stage. This paper discusses the ore-forming fluids, ore-forming materials, and deposit genesis of the Erentaolegai silver deposits using fluid inclusions microthermometry, laser Raman spectroscopy, and H-O-S isotope analyses. Fluid inclusion microthermometry and laser Raman spectroscopy analyses indicate that the Erentaolegai silver deposit contains exclusively fluid-rich two-phase fluid inclusions, all of which belong to the H2O-NaCl system. Homogenization temperatures of fluid inclusions in the three stages (from early to late) ranged from 257 to 311 °C, 228 to 280 °C, and 194 to 238 °C, corresponding to salinities of 1.91 to 7.86 wt%, 2.07 to 5.41 wt%, and 0.70–3.55 wt% NaCl equivalent, densities of 0.75 to 0.83 g/cm−3, 0.80 to 0.86 g/cm−3 and 0.85 to 0.89 g/cm−3. The mineralization pressure ranged from 12.2 to 29.5 MPa, and the mineralization depth was 0.41 to 0.98 km, indicating low-pressure and shallow-depth mineralization conditions. H-O isotope results indicate that the ore-forming fluid is a mixture of magmatic fluids and meteoric water, with meteoric contribution dominating in the late stage. The δ34S values of metallic sulfides ranged from −1.8 to +4.0‰, indicating that the metallogenic material of the Erentaolegai silver deposit was dominated by a deep magmatic source. This study concludes that meteoric water mixing and subsequent fluid cooling served as the primary mechanism for silver mineral precipitation. The Erentaolegai silver deposit is classified as a low-sulfidation epithermal silver deposit. Full article
(This article belongs to the Special Issue Recent Developments in Rare Metal Mineral Deposits)
Show Figures

Figure 1

21 pages, 28944 KiB  
Article
Tracing Sulfate Sources of Surface Water and Groundwater in Liuyang River Basin Based on Hydrochemistry and Environmental Isotopes
by Lei Wang, Yi Li, Yanpeng Zhang, Wei Liu and Hongxin Zhang
Water 2025, 17(14), 2105; https://doi.org/10.3390/w17142105 - 15 Jul 2025
Viewed by 255
Abstract
Sulfate as a potential pollution source in the water environment of the basin, identifying sulfate sources and migration mechanisms is essential for protecting the water environment and ensuring sustainable water management. Liuyang River is a primary tributary of the Xiangjiang River. It has [...] Read more.
Sulfate as a potential pollution source in the water environment of the basin, identifying sulfate sources and migration mechanisms is essential for protecting the water environment and ensuring sustainable water management. Liuyang River is a primary tributary of the Xiangjiang River. It has experienced progressively intensifying anthropogenic influences in recent decades, manifested by sustained sulfate concentration increases. However, the sulfate sources and their contributions were not clear. This study used hydrochemistry and multi-isotopes methods combined with Simmr model to study the hydrochemical characteristics, sulfate sources, and migration–transformation processes of surface water and groundwater. The results showed that the hydrochemical types of surface water were HCO3-Ca and HCO3·SO4-Ca·Mg, and groundwater were HCO3-Ca, HCO3-Ca·Mg, and HCO3·SO4-Ca. Ions in the water primarily originated from carbonate and silicate rocks dissolution and sulfide oxidation, augmented by mining operations, sewage discharge, and chemical production. The analyses of hydrochemistry, isotopes, and Simmr model revealed that surface water sulfate originated from soil sulfate (35.70%), sulfide oxidation (26.56%), sewage (16.58%), and atmospheric precipitation (12.45%). Groundwater sulfate was derived predominantly from sewage (34.96%), followed by soil sulfate (28.09%), atmospheric precipitation (17.35%), and sulfide oxidation (12.25%). Sulfate migration and transformation were controlled by the natural environment and anthropogenic impacts. When unaffected by human activities, sulfate mainly originated from soil and atmospheric precipitation, relating to topography, geological conditions, agricultural activities, and precipitation intensity. However, in regions with intense human activities, contributions from sewage and sulfide oxidation significantly increased due to the influences of mining and industrial activities. Full article
(This article belongs to the Special Issue Groundwater Quality and Contamination at Regional Scales)
Show Figures

Figure 1

21 pages, 2742 KiB  
Article
Origin Traceability of Chinese Mitten Crab (Eriocheir sinensis) Using Multi-Stable Isotopes and Explainable Machine Learning
by Danhe Wang, Chunxia Yao, Yangyang Lu, Di Huang, Yameng Li, Xugan Wu, Weiguo Song and Qinxiong Rao
Foods 2025, 14(14), 2458; https://doi.org/10.3390/foods14142458 - 13 Jul 2025
Viewed by 342
Abstract
The Chinese mitten crab (Eriocheir sinensis) industry is currently facing the challenges of origin fraud, as well as a lack of precision and interpretability of existing traceability methods. Here, we propose a high-precision origin traceability method based on a combination of [...] Read more.
The Chinese mitten crab (Eriocheir sinensis) industry is currently facing the challenges of origin fraud, as well as a lack of precision and interpretability of existing traceability methods. Here, we propose a high-precision origin traceability method based on a combination of stable isotope analysis and interpretable machine learning. We sampled Chinese mitten crabs from six origins representing diverse aquatic environments and farming practices, and analyzed their δ13C, δ15N, δ2H, and δ18O stable isotope compositions in different sexes and tissues (hepatopancreas, muscle, and gonad). By comparing the classification performance of Random Forest, XGBoost, and Logistic Regression models, we found that the Random Forest model outperformed the others, achieving high accuracy (91.3%) in distinguishing samples from different origins. Interpretation of the optimal Random Forest model, using SHAP (SHapley Additive exPlanations) analysis, identified δ2H in male muscle, δ15N in female hepatopancreas, and δ13C in female hepatopancreas as the most influential features for discriminating geographic origin. This analysis highlighted the crucial role of environmental factors, such as water source, diet, and trophic level, in origin discrimination and demonstrated that isotopic characteristics of different tissues provide unique discriminatory information. This study offers a novel paradigm for stable isotope traceability based on explainable machine learning, significantly enhancing the identification capability and reliability of Chinese mitten crab origin traceability, and holds significant implications for food safety assurance. Full article
(This article belongs to the Section Food Analytical Methods)
Show Figures

Figure 1

19 pages, 15843 KiB  
Article
Hydrochemical Characteristics and Formation Mechanisms of Groundwater in the Nanmiao Emergency Groundwater Source Area, Yichun, Western Jiangxi, China
by Shengpin Yu, Tianye Wang, Ximin Bai, Gongxin Chen, Pingqiang Wan, Shifeng Chen, Qianqian Chen, Haohui Wan and Fei Deng
Water 2025, 17(14), 2063; https://doi.org/10.3390/w17142063 - 10 Jul 2025
Viewed by 288
Abstract
The Nanmiao Emergency Groundwater Source Area, rich in H2SiO3, serves as a strategic freshwater reserve zone in western Jiangxi Province. However, the mechanisms underlying groundwater formation in this area remain unclear. This study applied a combination of statistical analysis, [...] Read more.
The Nanmiao Emergency Groundwater Source Area, rich in H2SiO3, serves as a strategic freshwater reserve zone in western Jiangxi Province. However, the mechanisms underlying groundwater formation in this area remain unclear. This study applied a combination of statistical analysis, isotopic tracing, and hydrochemical modeling to reveal the hydrochemical characteristics and origins of groundwater in the region. The results indicate that Na+ and Ca2+ dominate the cations, while HCO3 and Cl dominate the anions. Groundwater from descending springs is characterized by low mineralization and weak acidity, with hydrochemical types of primarily HCO3–Na·Mg and HCO3–Mg·Na·Ca. Groundwater from boreholes is weakly mineralized and neutral, with dominant hydrochemical types of HCO3–Ca·Na and HCO3–Ca·Na·Mg, suggesting a deep circulation hydrogeochemical process. Hydrogen and oxygen isotope analysis indicates that atmospheric precipitation is the primary recharge source. The chemical composition of groundwater is mainly controlled by rock weathering, silicate mineral dissolution, and cation exchange processes. During groundwater flowing, water and rock interactions, such as leaching, cation exchange, and mixing, occur. This study identifies the recharge sources and circulation mechanisms of regional groundwater, offering valuable insights for the sustainable development and protection of the emergency water source area. Full article
(This article belongs to the Special Issue Advances in Surface Water and Groundwater Simulation in River Basin)
Show Figures

Figure 1

22 pages, 2041 KiB  
Article
An Improved and Updated Method for the Determination of Imidazole Compounds in Geological Samples
by Henan Li, Zhiling You, Kunde Lin, Yuncong Ge, Qian Wang and Meng Chen
Water 2025, 17(14), 2062; https://doi.org/10.3390/w17142062 - 10 Jul 2025
Viewed by 300
Abstract
The widespread environmental dissemination of imidazole compounds necessitates robust analytical monitoring tools. This study developed a novel isotope-labeled surrogate-based high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of 21 imidazoles in water, sediment, and soil. The optimized [...] Read more.
The widespread environmental dissemination of imidazole compounds necessitates robust analytical monitoring tools. This study developed a novel isotope-labeled surrogate-based high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of 21 imidazoles in water, sediment, and soil. The optimized SPE protocol using Oasis HLB cartridges achieved high recoveries, with chromatographic separation completed in 25 min. Six isotope-labeled standards effectively corrected matrix effects (−57% to 8%), yielding MQLs < 1.0 ng·L−1 (water) and <1.0 μg·kg−1 (sediment/soil). Validation confirmed linearity (R2 > 0.995), accuracy (60–120% recovery for 20/21 analytes), and precision (relative standard deviation, RSD < 15%). Its application in Jiulong River revealed significant contamination, detecting eight imidazoles in both water (up to 49.29 ng·L−1) and sediment (up to 24.01 μg·kg−1). This standardized tool enables routine monitoring of pharmaceutical residues across environmental compartments, supporting regulatory frameworks. Full article
(This article belongs to the Section Water Quality and Contamination)
Show Figures

Figure 1

13 pages, 4462 KiB  
Article
Potential Function of Microbial Mats in Regard to Water Chemistry and Carbonate Precipitation in the Alkaline Waterbody Lake Van (Turkey)
by Marianna Cangemi, Ygor Oliveri, Bilge Sasmaz, Paolo Censi and Ahmet Sasmaz
Water 2025, 17(14), 2060; https://doi.org/10.3390/w17142060 - 10 Jul 2025
Viewed by 334
Abstract
In this article, we examine water chemistry and carbonate precipitation in the alkaline waterbody Lake Van in Turkey, analyzing the possible role of microbial communities in stromatolite formation. Lake Van represents a unique environment characterized by high salinity and pH and extensive microbial [...] Read more.
In this article, we examine water chemistry and carbonate precipitation in the alkaline waterbody Lake Van in Turkey, analyzing the possible role of microbial communities in stromatolite formation. Lake Van represents a unique environment characterized by high salinity and pH and extensive microbial communities, as revealed by SEM observation. Microbial activity, including that of cyanobacteria, can influence carbonate precipitation processes, leading to the formation of authigenic carbonates through physicochemical or metabolic mechanisms such as photosynthesis or sulfate reduction. In these environments, which are often dominated by cyanobacteria, carbonate precipitation can be influenced by biologically induced processes. This study presents new data on the hydrochemistry of lake water, focusing on the behavior of rare-earth elements (REEs) in this water and the carbon and oxygen isotopic compositions of carbonate microbial mats. The oxygen isotope data suggest that inorganic carbonate precipitation is the dominant process, but a biological influence on inorganic precipitation cannot be ruled out. For a deeper understanding of the role of biological processes in Lake Van, further studies on microbialites are needed. Full article
(This article belongs to the Section Hydrogeology)
Show Figures

Figure 1

Back to TopTop