Journal of contaminant hydrology最新文献

{"title":"Removal efficiency and microbial community shifts in full-scale versus laboratory-scale bank filtration systems using horizontal collector wells.","authors":"Sang Yeob Kim, Jin Hyung Noh, Minjoo Lee, Joonhong Park, Young Joo Lee, Jeong Joo Park, Heejong Son, Woorim Lee, Feifei Wang, Sung Kyu Maeng","doi":"10.1016/j.jconhyd.2025.104689","DOIUrl":"10.1016/j.jconhyd.2025.104689","url":null,"abstract":"<p><p>Climate-induced changes in dissolved organic matter (DOM) and trace organic contaminants (TrOCs) present growing challenges for drinking water treatment, particularly in surface water-dependent regions. Bank filtration (BF), a natural subsurface treatment process, offers a sustainable solution, but its performance and scalability require further validation. This study simultaneously assesses the performance of laboratory-scale and full-scale BF systems using a horizontal collector well (HCW), both receiving the same source water and aquifer materials, to remove DOM and TrOCs, and to investigate changes in microbial communities under equivalent residence times (20 days). The full-scale HCW system achieved a 63.0 % DOM removal rate compared to 37.0 % in laboratory-scale columns, effectively reducing biopolymers and humic substances through soil passage. Microbial analysis revealed distinct shifts, with Proteobacteria comprising 80.1 % of the full-scale filtrate compared to 59.1 % in the laboratory-scale. Total cell counts and microbial activity decreased by 85.0 % and 90.4 % in the full-scale system, respectively. The removal efficiency for 60 selected TrOCs varied by their properties: hydrophobic ionic compounds achieved high removal (91.2 %), while hydrophilic and neutral compounds, including perfluoroalkyl substances (PFAS), showed lower removal rates (37.3 % and 24.5 %, respectively). Pharmaceuticals, steroid hormones, and pesticides were effectively removed, with some exceeding 99.9 %. This study is the first to directly compare full-scale HCW and laboratory-scale BF systems under controlled conditions. These findings highlight BF's effectiveness and the need for integrating complementary technologies to improve water quality and sustainability.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"275 ","pages":"104689"},"PeriodicalIF":4.4,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144816833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Removal of Fe(II) from water using raw and calcinated weathered basalt: Influence of mineralogy and physical properties.","authors":"Ali M El Shafey, Ahmed M Zayed, Hanafy M Abd El-Salam, Mahmoud S M Abdel Wahed","doi":"10.1016/j.jconhyd.2025.104692","DOIUrl":"10.1016/j.jconhyd.2025.104692","url":null,"abstract":"<p><p>In this study, raw weathered basalt (RWB) and calcinated weathered basalt (CWB), both low-cost natural geological materials, were employed for the removal of Fe(II) from contaminated aqueous solutions and groundwater. CWB was prepared by calcining RWB at 900 °C for 3 h. Batch adsorption experiments were conducted, and the data fitted best with the Langmuir isotherm model. The adsorption kinetics followed the pseudo-second-order and intra-particle diffusion models. Although calcination improved the surface area and porosity, RWB exhibited higher Fe(II) removal efficiency, likely due to its richer mineralogical composition, particularly the clay content. The results suggest that modification by calcination does not necessarily enhance adsorption performance. The proposed mechanisms involve chemisorption, electrostatic attraction, cation exchange, surface complexation, and adsorption-oxidation. Additionally, RWB showed better performance than CWB in reducing Mn, Ca hardness, NH₃, NO₃^-, NO₂^-, and TDS during groundwater treatment. Therefore, RWB offers a more cost-effective and sustainable option for water purification without requiring energy-intensive modification.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"275 ","pages":"104692"},"PeriodicalIF":4.4,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144812024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of carbon-14 trichloroethene to determine degradation rate constants in rock core microcosms.","authors":"Hao Wang, Rong Yu, Ramona Darlington Iery, Lawrence C Murdoch, Ronald W Falta, David L Freedman","doi":"10.1016/j.jconhyd.2025.104752","DOIUrl":"https://doi.org/10.1016/j.jconhyd.2025.104752","url":null,"abstract":"<p><p>It is challenging to obtain degradation rate constants for chlorinated solvents (e.g., trichloroethene, TCE) that reside within low permeability formations such as fractured bedrock. Degradation rates are needed to evaluate remediation strategies. The overall objective of this research was to determine rate constants for degradation of TCE in rock core samples from fractured bedrock aquifers at three Department of Defense sites. In a prior study (Wang et al., 2024), core samples were used in novel intact rock microcosms that were infused with TCE and carbon-14 (¹⁴C-) labeled TCE. Uncontaminated groundwater was circulated through the headspace of the microcosms (i.e., the simulated fracture space) to induce diffusion out of the core that simulated back diffusion from a low permeability rock matrix. Four incubation conditions were evaluated based on the composition of the groundwater circulated through the simulated fracture space: unamended (i.e., no electron donor or sulfate added); lactate amended; lactate + sulfate amended; and mercuric chloride amended. In addition to monitoring the formation of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), data were collected on non-chlorinated degradation products that accumulated in the microcosms, including dissolved gases (i.e., acetylene, ethene, ethane) and ¹⁴C-labeled soluble compounds. The rates at which the non-chlorinated degradation products accumulated were used to estimate pseudo-first-order rate constants by inverting numerical simulations. Rate constants for unamended treatments that best represent in situ conditions ranged from 0.013 to 0.049 yr^-1 and are statistically equivalent to the constants characterizing treatments that were amended with mercuric chloride to inhibit microbial activity. ¹⁴C-labeled degradation products accounted for 75-90 % of the rate constants; not including these products would underestimate TCE degradation potential. Lactate and lactate + sulfate amended microcosms had statistically higher rate constants for TCE degradation (ranging from 0.034 to 0.13 yr^-1) compared to unamended microcosms. Although numerical simulation of intact rock core microcosms infused with ¹⁴C-labeled compounds is more time-consuming and complex than other methods to assess TCE degradation potential in low permeability media, the resulting rate constants provide a robust estimate of the potential for TCE degradation in situ.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"104752"},"PeriodicalIF":4.4,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145300713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic distribution characteristics and ecological risks of antibiotics in typical subtropical tidal river","authors":"Bowen Li ,&nbsp;Bo Li ,&nbsp;Qunpo Jia ,&nbsp;Yanpeng Cai ,&nbsp;Xiao Yuan ,&nbsp;Zhifeng Yang","doi":"10.1016/j.jconhyd.2025.104741","DOIUrl":"10.1016/j.jconhyd.2025.104741","url":null,"abstract":"<div><div>Antibiotics have garnered increasing global concern due to their frequent detection and persistence in the environment, which can lead to ecological risks, biological resistance, posing a potential threat to ecosystem and human health. This study investigated the occurrence of antibiotics in a typical tidal channel located in the lower reaches of the Dongjiang River during both wet and dry seasons. Additionally, high-frequency continuous dynamic monitoring was conducted over a full tidal cycle at a tidal-influenced section. The total concentrations of antibiotics ranged from 11.46 to 940.53 ng/L in the wet season and from 15.08 to 322.31 ng/L in the dry season. Fluoroquinolones, particularly ciprofloxacin, were the predominant antibiotics detected. Concentrations were significantly higher in the wet season compared to the dry season. Spatially, antibiotic levels exhibited a pattern with higher concentrations in the upstream and downstream regions and lower concentrations in the middle section. Furthermore, antibiotic concentrations showed a clear tidal influence, with the lowest levels observed during ebb tide and the highest during flood tide. Ecological risk assessment indicated that antibiotics posed higher ecotoxicological risks in the wet season than in the dry season, with fluoroquinolones representing the highest risk category. The potential for antimicrobial resistance was relatively high for ciprofloxacin, moderate for ofloxacin and norfloxacin, suggesting that these compounds should be prioritized in risk management strategies. In contrast, human health risks associated with antibiotic exposure were found to be negligible. These findings offer valuable insights into the behavior and management of antibiotic pollution in tidal rivers.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104741"},"PeriodicalIF":4.4,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predictive modelling and optimization of electrocoagulation for nitrate removal using deep learning: Toward intelligent and sustainable water treatment.","authors":"Harun Çiğ, Fatma Didem Alay, Benan Yazıcı Karabulut","doi":"10.1016/j.jconhyd.2025.104751","DOIUrl":"https://doi.org/10.1016/j.jconhyd.2025.104751","url":null,"abstract":"<p><p>This study investigates the optimization of the electrocoagulation (EC) process for nitrate (NO₃^-) removal from synthetic wastewater through the application of advanced deep learning methodologies. A hybrid model integrating Convolutional Neural Networks (CNN) and Long Short-Term Memory (LSTM) networks was developed to exploit both spatial feature extraction and temporal sequence learning capabilities. The synergy of CNN and LSTM enabled more accurate modelling of the complex, time-dependent behaviour of the EC process. Electrocoagulation (EC) was further optimized using a Box-Behnken design to evaluate the effects of six key variables-pH, initial NO₃^- concentration, conductivity, voltage, current, and reaction time-on NO₃^- removal efficiency. The resulting statistical model, supported by high coefficient values, demonstrated strong predictive capability for estimating NO₃^- removal performance. Model performance was systematically enhanced through hyperparameter tuning using the Random Search algorithm, while the Early Stopping technique was employed to prevent overfitting. Several machine learning and deep learning models were constructed and comparatively evaluated based on established performance metrics, including MSE, RMSE, MAE, MAPE, and R². The XGBoost model demonstrated superior predictive performance, yielding the lowest values for MSE (44.77), RMSE (6.69), and MAE (4.93). Furthermore, the high R² (0.96) and adjusted R² (0.94) values indicate that the model effectively captured a substantial proportion of the variance within the dataset. However, the CNN-LSTM hybrid model also showed excellent performance and was ultimately identified as the most effective deep learning approach due to its ability to capture spatiotemporal dynamics. Beyond predictive performance, the study also addressed energy consumption and operational cost analyses, contributing to a holistic evaluation of system sustainability. The average costs were calculated as $0.46/m³ for Al, $0.55/m³ for Fe, and $0.25/m³ for the Al/Fe combination electrodes. Accordingly, an optimized system design was proposed to maximize NO₃^- removal efficiency, minimize energy usage, and promote environmentally sustainable practices. In 5-fold cross-validation, XGBoost achieved the highest accuracy (R² = 0.932 ± 0.051), while CNN-LSTM showed comparable reliability but lower performance (R² = 0.886 ± 0.056). The paired Wilcoxon test yielded p = 0.0679, indicating a borderline, non-significant difference. The results underscore the potential of hybrid deep learning architectures in environmental modelling and provide a robust framework for the development of intelligent, cost-effective, and green water treatment technologies.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"104751"},"PeriodicalIF":4.4,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145292374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the impacts of sodium polyacrylate discharge into the Seine River: A numerical modeling approach.","authors":"Mohamed Bey-Zekkoub, Pablo Tassi, Norinda Chhim","doi":"10.1016/j.jconhyd.2025.104740","DOIUrl":"https://doi.org/10.1016/j.jconhyd.2025.104740","url":null,"abstract":"<p><p>By using a numerical modeling approach, this study investigates sodium polyacrylate's environmental fate upon discharge into the Seine River, examining its adsorption to suspended sediments, water column transport, and bed sediment accumulation. Utilizing laboratory experiments and numerical modeling, the research evaluated polymer transport dynamics and accumulation patterns relative to environmental toxicity thresholds. While high dilution minimized aquatic organism impacts, bed sediment accumulation potentially threatened soil species like plants and earthworms. Discharging the polymer in adsorbed form reduced aquatic exposure but increased sediment accumulation. Post-discharge, sediment properties and flow conditions significantly influenced polymer immobilization, with low flow and bed resistance prolonging the remobilization process.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"104740"},"PeriodicalIF":4.4,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145292385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution and origins of iron-rich groundwater in shallow and deep aquifers of the Hebei plain","authors":"Gangli Yan ,&nbsp;Guanxing Huang","doi":"10.1016/j.jconhyd.2025.104748","DOIUrl":"10.1016/j.jconhyd.2025.104748","url":null,"abstract":"<div><div>Fe-rich (&gt; 0.3 mg/L) groundwater is common in coastal plains and limits the utility of groundwater, because groundwater with high concentrations of Fe is not suitable for drinking, industrial, and agricultural purposes. Nowadays, the Hebei Plain is a large scale coastal plain in China, its groundwater Fe distribution and origins still remain unclear. This study aims to investigate the distribution of Fe in shallow and deep groundwater in different land uses in various sub-plains across the Hebei Plain, and to discuss origins for Fe-rich groundwater in various sub-plains. Results showed that Fe-rich groundwater mainly occurred in both of central and littoral sub-plains (CSP and LSP) in comparison with the piedmont sub-plain (PSP). Proportions of Fe-rich groundwater in shallow aquifers were 1.5–2 times that in deep aquifers in various sub-plains. In the PSP, Fe-rich shallow groundwater in rural areas and woods-grasslands were more than double that in other land use types, while Fe-rich deep groundwater occurred in agricultural lands but absent in other lands. In the CSP, proportions of Fe-rich shallow groundwater in different land use types were about 36 %–43 %, while Fe-rich deep groundwater occurred in both of woods-grasslands and agricultural lands but absent in rural areas. In the LSP, proportions of Fe-rich shallow groundwater in different land use types were about 38 %–50 %. Anaerobic NH₄⁺ oxidation coupled to Fe(III) minerals reduction in Quaternary sediments was responsible for the occurrence of Fe-rich groundwater in shallow aquifers of CSP and LSP and in deep aquifers of the PSP, but one of driving mechanisms for the occurrence of Fe-rich groundwater in shallow aquifers of the PSP and in deep aquifers of the CSP. Dissolved-Fe(III) from the leaching of thickened vadose zones (or aquitards) because of the failing of groundwater table was likely another driving force for the occurrence of Fe-rich groundwater in shallow aquifers of the PSP and in deep aquifers of the CSP. On the other hand, NO₃⁻ reducing accompanied with Fe(II) oxidizing and Fe(II) oxidation by oxygen were likely two mechanisms inhibiting the occurrence of Fe-rich shallow groundwater in the PSP. Besides, the former one also restrained the occurrence of Fe-rich deep groundwater in the PSP. Therefore, in the future, strengthening the input of external water for elevating the groundwater table to inhibit Fe-rich shallow groundwater in the PSP and Fe-rich deep groundwater in the CSP and controlling NO₃⁻ input for restraining Fe-rich shallow and deep groundwaters in the PSP are recommended. Besides, we also recommend long-term monitoring of groundwater Fe in the Hebei Plain to enhance the groundwater resources management.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104748"},"PeriodicalIF":4.4,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical modeling, evaluation of contaminants and impacts of land use, land cover patterns on groundwater quality in Khushab, Pakistan","authors":"Hasnain Abbas ,&nbsp;Javed Iqbal ,&nbsp;Syed Madhi Haider Kazmi ,&nbsp;Maqsood Ahmed ,&nbsp;Muhammad Ismail ,&nbsp;Wajid Hussain","doi":"10.1016/j.jconhyd.2025.104746","DOIUrl":"10.1016/j.jconhyd.2025.104746","url":null,"abstract":"<div><div>Urbanization and land use/land cover (LULC) transitions exert significant pressure on groundwater resources, particularly in semi-arid regions where reliance on groundwater is high. This study assessed the effects of LULC on groundwater hydrochemistry in Khushab district, Pakistan, by analyzing 155 groundwater samples alongside geospatial mapping and statistical modeling. Hydrochemical distribution patterns revealed elevated sodium (Na⁺), chloride (Cl⁻), sulfate (SO₄²⁻), fluoride (F⁻), and magnesium (Mg²⁺) concentrations in agricultural and urban zones, reflecting inputs from fertilizers, wastewater infiltration, and industrial activities. The Curved Streamline Searchlight Model (CS-SLM) identified distinct LULC and ion linkages: Na⁺, Cl⁻ and F⁻ associations in agricultural land, SO₄²⁻, Mg²⁺ and Na⁺ relationships in built-up areas, and Na⁺, Mg²⁺ and Cl⁻ correlations in rangelands. To assess future risks, LULC dynamics were simulated using a Multilayer Perceptron and Markov Chain Analysis (MLP-MCA) model, projecting substantial increases in agriculture (+14.7 %), built-up land (+25.4 %), and forest (+23.5 %) by 2030, accompanied by declines in rangeland (−24.3 %) and water bodies (−15.8 %). These changes are expected to further elevate Na⁺, Cl⁻, SO₄²⁻, and Mg²⁺ levels in agricultural and urban aquifers, posing risks to groundwater quality and sustainability. The findings provide new evidence that rapid LULC change directly shapes groundwater chemistry, highlighting the urgent need for integrated land and water management practices. Sustainable agricultural inputs, improved wastewater management, and protective policies for rangelands and water bodies are essential to mitigate future degradation of groundwater resources.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104746"},"PeriodicalIF":4.4,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Denitrification and isotope fractionation effects under simulated aquifer conditions at a laboratory scale","authors":"Qifang Chen ,&nbsp;Yuemin Hu ,&nbsp;Fan Chen ,&nbsp;Junfeng Zhang ,&nbsp;Zanfang Jin ,&nbsp;Linyun Xiao ,&nbsp;Xiang Chen ,&nbsp;Yasheng Shi ,&nbsp;Feili Li","doi":"10.1016/j.jconhyd.2025.104749","DOIUrl":"10.1016/j.jconhyd.2025.104749","url":null,"abstract":"<div><div>Denitrification plays a critical role in controlling the fate of nitrate (NO₃⁻) in groundwater. The nitrogen isotope enrichment factor (εN) during denitrification is essential for quantifying the role of denitrification in nitrate reduction in groundwater. Experimental columns containing groundwater and sediment were established to simulate aquifer conditions. Denitrification rates and the N and O isotope fractionation effects of NO₃⁻ in both groundwater and sediment during dentrification were measured in experimental columns using four organic substances as electron donors (ethanol, acetate, glucose and brown sugar) under two different dissolved oxygen (DO) concentrations of 1 and 2 mg·L⁻¹, respectively. Significant variations in denitrification rates and stable isotope enrichment factors were observed in both overlying groundwater (εN_o and εO_o) and sediment pore water (εN_p and εO_p), depending on the carbon source and DO concentration. At DO =2 mg·L⁻¹, acetate (εN_o, −9.2 ‰; εN_p, −7.4 ‰), glucose (εN_o, −7.4 ‰; εN_p, −4.3 ‰), brown sugar (εN_o, −2.6 ‰; εN_p, −2.4 ‰) exhibited less negative isotope enrichment factors compared to ethanol (εN_o, −11.7 ‰; εN_p, −10.0 ‰). For brown sugar, more negative isotope enrichment factors was observed at DO =1 (εN_o, −5.0 ‰; εN_p, −3.5 ‰) than at DO = 2 mg·L⁻¹. Higher denitrification rates correlated with more negative εN_o and εN_p values, reflecting stronger nitrogen fractionation. Due to the O-exchange fraction and NO₃⁻ reduction processes, positive εO_o and εO_p values were observed in the denitrification columns, ranging from 5.0 ‰ to 29.2 ‰ for εO_o and from 3.9 ‰ to 22.8 ‰ for εO_p. Fractionation by diffusive transport of NO₃⁻ resulted in higher absolute values of εN_o (εO_o) compared to those of εN_p (εO_p). The calculated isotope enrichment factors (εN_o and εN_p) may be applied to quantify denitrification linked to C sources application under in situ conditions.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104749"},"PeriodicalIF":4.4,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145268023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A nationwide study on the occurrence, driving factors and exposure assessment of typical pesticides in groundwater in China","authors":"Shengpin Li ,&nbsp;Jiaqing Liu ,&nbsp;Fei Liu ,&nbsp;Wenpeng Li ,&nbsp;Kun Liu ,&nbsp;Haitao Piao ,&nbsp;Rui An ,&nbsp;Yiwei Zhang ,&nbsp;Tuoya Tai ,&nbsp;Qianying Zhu ,&nbsp;Fuyang Huang","doi":"10.1016/j.jconhyd.2025.104743","DOIUrl":"10.1016/j.jconhyd.2025.104743","url":null,"abstract":"<div><div>Pesticides are widely used in agricultural production, and their residues migrate to aquifers, threatening groundwater safety. This study investigated the occurrence and distribution characteristics of 18 typical pesticide components in different environmental media in China. Meanwhile, the driving factors of the migration and transformation of pesticide components in groundwater were identified. The results show that among 20,010 groundwater monitoring sites, the proportions of the average concentrations of the 18 pesticide components at not detected (ND), ND-1 μg/L, 0.1–1 μg/L, and greater than 1 μg/L are 40.42 %, 25.85 %, 26.59 %, and 7.14 %, respectively. Among 15 groundwater resource regions, the proportions of groundwater with average pesticide concentrations greater than 1 μg/L in the Liaohe River Basin, Songhua River Basin, and Huaihe River Basin are 22.92 %, 16.62 %, and 10.92 % respectively. The detected concentration of pesticides in groundwater decreases significantly with increasing monitoring depth. Based on the multi-factor analysis of the source-sink processes of pesticides in groundwater, pesticides tend to accumulate in phreatic aquifers with relatively more rainfall, shorter sunshine duration, higher permeability of the vadose zone, a primarily reducing environment, and TDS less than 1000 mg/L. In some monitoring sites with phreatic aquifers, pesticide components of chlorpyrifos, pentachlorophenol, 1,2,3,4,5,6-hexachlorocyclohexane, lindane, hexachlorobenzene, heptachlor and malathion pose non-carcinogenic and carcinogenic risks to human health.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104743"},"PeriodicalIF":4.4,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}