Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100498
Ryul Kim, Young Hwan Choi
In South Korea, rapid aging and regional decline have accelerated depopulation, creating significant challenges for the sustainable management of infrastructure systems. Therefore, small- and medium-sized cities in Korea are vulnerable, as declining demand threatens the long-term reliability of water distribution systems (WDSs). Traditional WDSs are conservatively designed with the expectation of population growth, leading to overcapacity when the demand decreases. This mismatch results in underutilized pipes, prolonged residence times, and associated hydraulic and water quality deterioration. To address these issues, this study introduces a structural reconfiguration framework that identifies and isolates nonessential pipes using spectral graph theory, followed by multi-objective optimization to balance efficiency and reliability. Extended period simulations indicate that demand reduction in peripheral areas accelerate chlorine decay and induce network-wide hydraulic imbalances. By closing redundant pipes and eliminating unnecessary pipes, the proposed approach reduces maintenance costs while improving the water quality performance. The findings highlight the structural drivers of WDS degradation under depopulation and provide an analytical framework that supports structural decision-making for urban water infrastructure under depopulation.
{"title":"Structural optimization of water distribution systems in South Korea local cities facing depopulation driven hydraulic and water quality challenges","authors":"Ryul Kim, Young Hwan Choi","doi":"10.1016/j.wroa.2026.100498","DOIUrl":"10.1016/j.wroa.2026.100498","url":null,"abstract":"<div><div>In South Korea, rapid aging and regional decline have accelerated depopulation, creating significant challenges for the sustainable management of infrastructure systems. Therefore, small- and medium-sized cities in Korea are vulnerable, as declining demand threatens the long-term reliability of water distribution systems (WDSs). Traditional WDSs are conservatively designed with the expectation of population growth, leading to overcapacity when the demand decreases. This mismatch results in underutilized pipes, prolonged residence times, and associated hydraulic and water quality deterioration. To address these issues, this study introduces a structural reconfiguration framework that identifies and isolates nonessential pipes using spectral graph theory, followed by multi-objective optimization to balance efficiency and reliability. Extended period simulations indicate that demand reduction in peripheral areas accelerate chlorine decay and induce network-wide hydraulic imbalances. By closing redundant pipes and eliminating unnecessary pipes, the proposed approach reduces maintenance costs while improving the water quality performance. The findings highlight the structural drivers of WDS degradation under depopulation and provide an analytical framework that supports structural decision-making for urban water infrastructure under depopulation.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100498"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100501
Mengyao An , Qiang Liu , Zhaocai Wang , Yecang Chen
Dissolved oxygen (DO) is a fundamental indicator for aquatic ecological health and algal bloom early warning. To address the limitations of existing models in capturing multi-scale features and their reliance on empirical parameter tuning, this study proposes a novel integrated framework. First, a four-dimensional feature system incorporating target, peripheral, upstream, and meteorological variables is constructed. Second, the original DO series is decomposed into long-term trends and short-term fluctuations using Variational Mode Decomposition (VMD) and Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). An Improved Dung Beetle Optimization algorithm (IDBO) automatically optimizes the hyperparameters of VMD and the subsequent Convolutional Neural Network (CNN). The model employs a heterogeneous architecture where CNN extracts localized short-term features and an Improved Transformer (iTransformer) captures long-term dependencies. Experimental results at Lake Taihu and Dongting Lake sites demonstrate superior performance, with R² values reaching 0.9968 and 0.9942, significantly outperforming baseline models. Ablation studies confirm the substantial contributions of dual-modal decomposition and IDBO optimization. Furthermore, a stair-step water temperature control-oriented mechanism is established as a model-driven hypothetical control strategy, which proactively modulates DO levels by introducing a constant C. Setting C = 3 significantly increased the appropriate DO compliance rates from 30.3% and 74.7% to 61.9% and 97.2% at the two sites, respectively. This research provides a reliable closed-loop control-oriented technical pathway from precise prediction to active management for lake water quality, with the control-oriented mechanism based on the significant associative relationship between water temperature and DO rather than formal statistical causal inference.
{"title":"Fusing multi-dimensional features with heterogeneous deep learning for robust dissolved oxygen prediction and control-oriented regulation analysis in complex lakes","authors":"Mengyao An , Qiang Liu , Zhaocai Wang , Yecang Chen","doi":"10.1016/j.wroa.2026.100501","DOIUrl":"10.1016/j.wroa.2026.100501","url":null,"abstract":"<div><div>Dissolved oxygen (DO) is a fundamental indicator for aquatic ecological health and algal bloom early warning. To address the limitations of existing models in capturing multi-scale features and their reliance on empirical parameter tuning, this study proposes a novel integrated framework. First, a four-dimensional feature system incorporating target, peripheral, upstream, and meteorological variables is constructed. Second, the original DO series is decomposed into long-term trends and short-term fluctuations using Variational Mode Decomposition (VMD) and Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). An Improved Dung Beetle Optimization algorithm (IDBO) automatically optimizes the hyperparameters of VMD and the subsequent Convolutional Neural Network (CNN). The model employs a heterogeneous architecture where CNN extracts localized short-term features and an Improved Transformer (iTransformer) captures long-term dependencies. Experimental results at Lake Taihu and Dongting Lake sites demonstrate superior performance, with R² values reaching 0.9968 and 0.9942, significantly outperforming baseline models. Ablation studies confirm the substantial contributions of dual-modal decomposition and IDBO optimization. Furthermore, a stair-step water temperature control-oriented mechanism is established as a model-driven hypothetical control strategy, which proactively modulates DO levels by introducing a constant <em>C</em>. Setting <em>C</em> = 3 significantly increased the appropriate DO compliance rates from 30.3% and 74.7% to 61.9% and 97.2% at the two sites, respectively. This research provides a reliable closed-loop control-oriented technical pathway from precise prediction to active management for lake water quality, with the control-oriented mechanism based on the significant associative relationship between water temperature and DO rather than formal statistical causal inference.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100501"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2025.100474
Qiang Liu , Fengjiao Zhao , Chuanxing Zheng , Jijian Lian , Zhixiang Da , Maozhi Duan
With rapid urbanization, urban flooding has become increasingly severe, challenging conventional drainage systems. This study proposes an optimization framework for collaborative urban drainage that integrates Urban Micro-Watercourses (UMW), Low Impact Development (LID) facilities, and conventional drainage networks into a unified multi-level regulation system. The framework consists of two core modules: (1) an intelligent optimization module for LID facility planning, automatically determining optimal allocation ratios to maximize hydrological control; and (2) a layout optimization module for UMW, dynamically refining the spatial configuration of UMW networks to enhance collaborative drainage capacity. By establishing coordinated coupling among LID facilities, UMW networks, and conventional drainage systems, the framework enables integrated operation and resource sharing across subsystems, improving overall system performance and resilience. The parallelized framework led to a 46.8-fold increase in LID optimization efficiency and a 192.3-fold increase in UMW optimization efficiency. A case study in the Fangzhuang area of Beijing, under extreme rainfall scenarios with 5-, 10-, and 50-year return periods, showed total accumulated water volume reduced by 51.2 %–68.1 % and overflow points decreased by 18.1 %–73.3 %. Compared with the optimal LID scheme, the UMW–LID–pipe network coupling further reduced water volume by 7.85 %–21.77 % and overflow points by up to 64.94 %, substantially alleviating pressure on drainage infrastructure. The results demonstrate that the proposed framework provides an innovative and scalable approach for sustainable urban stormwater management and flood resilience.
{"title":"Optimization framework for urban flood mitigation strategies considering collaborative drainage mechanisms","authors":"Qiang Liu , Fengjiao Zhao , Chuanxing Zheng , Jijian Lian , Zhixiang Da , Maozhi Duan","doi":"10.1016/j.wroa.2025.100474","DOIUrl":"10.1016/j.wroa.2025.100474","url":null,"abstract":"<div><div>With rapid urbanization, urban flooding has become increasingly severe, challenging conventional drainage systems. This study proposes an optimization framework for collaborative urban drainage that integrates Urban Micro-Watercourses (UMW), Low Impact Development (LID) facilities, and conventional drainage networks into a unified multi-level regulation system. The framework consists of two core modules: (1) an intelligent optimization module for LID facility planning, automatically determining optimal allocation ratios to maximize hydrological control; and (2) a layout optimization module for UMW, dynamically refining the spatial configuration of UMW networks to enhance collaborative drainage capacity. By establishing coordinated coupling among LID facilities, UMW networks, and conventional drainage systems, the framework enables integrated operation and resource sharing across subsystems, improving overall system performance and resilience. The parallelized framework led to a 46.8-fold increase in LID optimization efficiency and a 192.3-fold increase in UMW optimization efficiency. A case study in the Fangzhuang area of Beijing, under extreme rainfall scenarios with 5-, 10-, and 50-year return periods, showed total accumulated water volume reduced by 51.2 %–68.1 % and overflow points decreased by 18.1 %–73.3 %. Compared with the optimal LID scheme, the UMW–LID–pipe network coupling further reduced water volume by 7.85 %–21.77 % and overflow points by up to 64.94 %, substantially alleviating pressure on drainage infrastructure. The results demonstrate that the proposed framework provides an innovative and scalable approach for sustainable urban stormwater management and flood resilience.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100474"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100488
Margareta Kračun-Kolarević , Bojana Žegura , Katja Kološa , Jovana Jovanović Marić , Andrea Novaković , Peter Oswald , Martina Oswaldova , Jaroslav Slobodnik , Nikiforos Alygizakis , Momir Paunović , Marija Ilić , Branka Vuković-Gačić , Stoimir Kolarević
The increasing complexity of aquatic pollution, dominated by diverse and often uncharacterized chemical mixtures, challenges traditional monitoring approaches. In this study, we assessed the genotoxic potential of surface water samples collected during the Joint Danube Survey 4 (JDS4) using large-volume solid-phase extraction (LVSPE) combined with a comprehensive battery of bioassays. Twenty-three enriched water samples from the Danube River and its major tributaries were evaluated for genotoxicity using a tiered testing strategy comprising the SOS/umuC assay, zebrafish liver (ZFL) cell-based assays (cytotoxicity, comet assay, cell cycle), and zebrafish embryo assays. While no genotoxicity was detected in the prokaryotic SOS/umuC assay, ZFL assays revealed significant DNA damage in 16 out of 23 samples, with notable genotoxicity observed in samples from the middle Danube section. In contrast, no teratogenic effects were observed in zebrafish embryo assays at concentrations up to REF100. These findings demonstrate the superior sensitivity of ZFL cells compared to both prokaryotic and in vivo embryo models. The study also highlights a critical gap in available genotoxicity data for detected substances, emphasizing the need for standardized databases and testing frameworks. Overall, our results support zebrafish-based in vitro assays as effective tools for effect-based monitoring, providing early warnings of genotoxic pollution in complex aquatic environments.
{"title":"Tiered genotoxicity testing of enriched river water samples using zebrafish in vitro and in vivo models: A Joint Danube Survey 4 case study","authors":"Margareta Kračun-Kolarević , Bojana Žegura , Katja Kološa , Jovana Jovanović Marić , Andrea Novaković , Peter Oswald , Martina Oswaldova , Jaroslav Slobodnik , Nikiforos Alygizakis , Momir Paunović , Marija Ilić , Branka Vuković-Gačić , Stoimir Kolarević","doi":"10.1016/j.wroa.2026.100488","DOIUrl":"10.1016/j.wroa.2026.100488","url":null,"abstract":"<div><div>The increasing complexity of aquatic pollution, dominated by diverse and often uncharacterized chemical mixtures, challenges traditional monitoring approaches. In this study, we assessed the genotoxic potential of surface water samples collected during the Joint Danube Survey 4 (JDS4) using large-volume solid-phase extraction (LVSPE) combined with a comprehensive battery of bioassays. Twenty-three enriched water samples from the Danube River and its major tributaries were evaluated for genotoxicity using a tiered testing strategy comprising the SOS/<em>umuC</em> assay, zebrafish liver (ZFL) cell-based assays (cytotoxicity, comet assay, cell cycle), and zebrafish embryo assays. While no genotoxicity was detected in the prokaryotic SOS/<em>umuC</em> assay, ZFL assays revealed significant DNA damage in 16 out of 23 samples, with notable genotoxicity observed in samples from the middle Danube section. In contrast, no teratogenic effects were observed in zebrafish embryo assays at concentrations up to REF100. These findings demonstrate the superior sensitivity of ZFL cells compared to both prokaryotic and <em>in vivo</em> embryo models. The study also highlights a critical gap in available genotoxicity data for detected substances, emphasizing the need for standardized databases and testing frameworks. Overall, our results support zebrafish-based <em>in vitro</em> assays as effective tools for effect-based monitoring, providing early warnings of genotoxic pollution in complex aquatic environments.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100488"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Ensuring the chemical safety of drinking water has become a growing concern as traditional pollutants are increasingly accompanied by emerging contaminants, including pharmaceuticals and other anthropogenic organic contaminants, as well as high-concern substances such as bisphenols and per- and polyfluoroalkyl substances (PFAS). Household filter jugs are widely promoted as a convenient solution to improve water quality, yet their actual performance and material safety remain insufficiently characterized. This study provides a comparative evaluation of six representative filtration systems available on the European market, focusing on their capacity to remove organic micropollutants while assessing possible leaching of polymer-associated substances. Results revealed marked differences in efficiency: four of the tested filter jugs achieved high removal rates whereas the remaining two systems showed limited performance. The limited removal of short-chain PFAS confirmed their lower adsorption affinity for hydrophobic sorbents, a pattern consistent with previous studies. Leaching analyses showed that some devices released manufacturing additives, including organophosphate esters, benzothiazole, and PFAS. From a toxicological perspective, PFAS released from certain devices contributed measurably to overall PFAS exposure, particularly in children, although calculated margins of exposure remained above safety thresholds. In addition, BPA was detected in one filtrate, indicating that filter materials can act as secondary contamination sources. Overall, the findings demonstrate that while household filters can effectively reduce chemical exposure, their performance is highly variable and may involve trade-offs between contaminant removal and material-related release. These results emphasize the need to expand certification standards.
{"title":"From adsorption to leaching: assessing micropollutants removal and contaminants release by household filter jugs","authors":"Léa Nowak , Nicola Bosisio , Loïc Sartori , Jérémy Beaud , Anne Onidi , Lionel Cretegny , Camille Rime , Davide Staedler , Fiorella Lucarini","doi":"10.1016/j.wroa.2026.100489","DOIUrl":"10.1016/j.wroa.2026.100489","url":null,"abstract":"<div><div>Ensuring the chemical safety of drinking water has become a growing concern as traditional pollutants are increasingly accompanied by emerging contaminants, including pharmaceuticals and other anthropogenic organic contaminants, as well as high-concern substances such as bisphenols and per- and polyfluoroalkyl substances (PFAS). Household filter jugs are widely promoted as a convenient solution to improve water quality, yet their actual performance and material safety remain insufficiently characterized. This study provides a comparative evaluation of six representative filtration systems available on the European market, focusing on their capacity to remove organic micropollutants while assessing possible leaching of polymer-associated substances. Results revealed marked differences in efficiency: four of the tested filter jugs achieved high removal rates whereas the remaining two systems showed limited performance. The limited removal of short-chain PFAS confirmed their lower adsorption affinity for hydrophobic sorbents, a pattern consistent with previous studies. Leaching analyses showed that some devices released manufacturing additives, including organophosphate esters, benzothiazole, and PFAS. From a toxicological perspective, PFAS released from certain devices contributed measurably to overall PFAS exposure, particularly in children, although calculated margins of exposure remained above safety thresholds. In addition, BPA was detected in one filtrate, indicating that filter materials can act as secondary contamination sources. Overall, the findings demonstrate that while household filters can effectively reduce chemical exposure, their performance is highly variable and may involve trade-offs between contaminant removal and material-related release. These results emphasize the need to expand certification standards.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100489"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2025.100471
Shimon Komarovsky , Raghad Shamaly , Gopinathan R. Abhijith , Andrea Cominola , Avi Ostfeld
Accurate water quality modeling in water distribution systems (WDS) is essential for ensuring safe and reliable drinking water. While numerical solvers such as EPANET provide robust simulations, their computational cost increases substantially for real-time or large-scale applications, particularly when boundary and initial conditions vary over time. Existing Physics-Informed Neural Network (PINN) approaches face limitations in handling such changing conditions, despite their prevalence in real WDS operations. This study focuses on enhancing the adaptability of PINNs for chlorine modeling under diverse and dynamic scenarios. The proposed framework embeds the governing Advection–Reaction (AR) equation into a deep learning architecture and introduces targeted modifications to the formulation of boundary and initial condition losses. Training data are generated using EPANET simulations, and the framework is evaluated under multiple scenarios, including constant and time-varying velocities as well as fixed and dynamic boundary and initial conditions. Results demonstrate that a PINN model explicitly designed for boundary-condition adaptability can accurately reproduce EPANET water quality simulations while reducing computational demands. Key factors influencing performance, such as proper PDE specification, loss balancing, and data preprocessing, are identified. Although the analysis is conducted on a single-pipe testbed to isolate these effects, the findings establish an essential foundation for extending adaptive PINNs to full WDS networks. The primary contribution of this work is the development and demonstration of a PINN architecture capable of reliably adapting to varying boundary and initial conditions, addressing a critical gap in current PINN-based water quality modeling research.
{"title":"Comparing different Physics-Informed Neural Network models for chlorine modeling in EPANET under varying initial and boundary conditions","authors":"Shimon Komarovsky , Raghad Shamaly , Gopinathan R. Abhijith , Andrea Cominola , Avi Ostfeld","doi":"10.1016/j.wroa.2025.100471","DOIUrl":"10.1016/j.wroa.2025.100471","url":null,"abstract":"<div><div>Accurate water quality modeling in water distribution systems (WDS) is essential for ensuring safe and reliable drinking water. While numerical solvers such as EPANET provide robust simulations, their computational cost increases substantially for real-time or large-scale applications, particularly when boundary and initial conditions vary over time. Existing Physics-Informed Neural Network (PINN) approaches face limitations in handling such changing conditions, despite their prevalence in real WDS operations. This study focuses on enhancing the adaptability of PINNs for chlorine modeling under diverse and dynamic scenarios. The proposed framework embeds the governing Advection–Reaction (AR) equation into a deep learning architecture and introduces targeted modifications to the formulation of boundary and initial condition losses. Training data are generated using EPANET simulations, and the framework is evaluated under multiple scenarios, including constant and time-varying velocities as well as fixed and dynamic boundary and initial conditions. Results demonstrate that a PINN model explicitly designed for boundary-condition adaptability can accurately reproduce EPANET water quality simulations while reducing computational demands. Key factors influencing performance, such as proper PDE specification, loss balancing, and data preprocessing, are identified. Although the analysis is conducted on a single-pipe testbed to isolate these effects, the findings establish an essential foundation for extending adaptive PINNs to full WDS networks. The primary contribution of this work is the development and demonstration of a PINN architecture capable of reliably adapting to varying boundary and initial conditions, addressing a critical gap in current PINN-based water quality modeling research.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100471"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100496
Xiao Sun , Lin Shi , Huang Zhang , Fangfang Li , Yanjin Long , Di Zhang
The environmental fate of extracellular DNA is significantly influenced by its interaction with widely used biochar. However, a systematic understanding of how DNA chain length and biochar properties jointly govern the adsorption process, mechanism, and subsequent DNA stability remains limited. This study systematically investigated the adsorption behaviors and mechanisms of short-stranded (sDNA) and long-stranded DNA (LDNA) on biochars produced at 300 – 600°C under neutral pH conditions. sDNA exhibited a higher adsorption capacity (5.91 mg g-1 on BC600) by accessing internal mesopores on biochar, whereas LDNA showed a lower adsorption (2.22 mg g-1 on BC600) and a stronger desorption hysteresis, resulting from multisite anchoring with biochars. The release rate values of sDNA and LDNA were 5 – 20% and 4 – 13% respectively on BC300. Correlation studies and desorption experiments revealed that π-π interactions and hydrophobic forces were the primary adsorption mechanisms. Spectroscopic analyses and molecular dynamic simulation confirmed conformational changes in the adsorbed DNA but showed no chain fragmentation. These findings underscore that DNA chain length and biochar properties jointly govern the sequestration and stability of DNA, providing essential mechanistic insights for assessing the role of biochar in the persistence and mobility of genetic material in the environment.
{"title":"Chain-length-dependent adsorption of extracellular DNA on biochar: Behaviors, mechanisms, and structural Stability","authors":"Xiao Sun , Lin Shi , Huang Zhang , Fangfang Li , Yanjin Long , Di Zhang","doi":"10.1016/j.wroa.2026.100496","DOIUrl":"10.1016/j.wroa.2026.100496","url":null,"abstract":"<div><div>The environmental fate of extracellular DNA is significantly influenced by its interaction with widely used biochar. However, a systematic understanding of how DNA chain length and biochar properties jointly govern the adsorption process, mechanism, and subsequent DNA stability remains limited. This study systematically investigated the adsorption behaviors and mechanisms of short-stranded (sDNA) and long-stranded DNA (LDNA) on biochars produced at 300 – 600°C under neutral pH conditions. sDNA exhibited a higher adsorption capacity (5.91 mg g<sup>-1</sup> on BC600) by accessing internal mesopores on biochar, whereas LDNA showed a lower adsorption (2.22 mg g<sup>-1</sup> on BC600) and a stronger desorption hysteresis, resulting from multisite anchoring with biochars. The release rate values of sDNA and LDNA were 5 – 20% and 4 – 13% respectively on BC300. Correlation studies and desorption experiments revealed that π-π interactions and hydrophobic forces were the primary adsorption mechanisms. Spectroscopic analyses and molecular dynamic simulation confirmed conformational changes in the adsorbed DNA but showed no chain fragmentation. These findings underscore that DNA chain length and biochar properties jointly govern the sequestration and stability of DNA, providing essential mechanistic insights for assessing the role of biochar in the persistence and mobility of genetic material in the environment.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100496"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100494
Kaidi Li , Junjun Deng , Hao Ma , Ziye Huang , Zanfang Jin , Wei Hu , Libin Wu , Pingqing Fu
Understanding the composition, sources, and transformation of rainwater dissolved organic matter (DOM) is critical for elucidating surface-atmosphere material transport and associated ecosystem impacts. This three-year (2020–2022) Hangzhou study characterized anthropogenically influenced rainwater DOM via integrated spectroscopic and modeling approaches. Results revealed strong anthropogenic imprints, with mean dissolved organic carbon (DOC) of 2.9 mg C L–1 and secondary ions dominating rainwater chemistry. Post-pandemic economic recovery in 2022 amplified fossil-fuel-combustion signatures and sulfate dominance, alongside a doubled DOC deposition flux (1.0 g C m⁻ (Iavorivska et al., 2016)). Summer DOC flux peaked at 0.32 g C m–2, driven by increased rainfall and secondary processes. Rainwater DOM featured optical indices FI, BIX, and HIX of 1.75 ± 0.17, 1.09 ± 0.31, and 1.32 ± 0.80, indicating low humification and aging degrees with anthropogenic and biological contributions. Parallel Factor Analysis (PARAFAC) identified two humic-like substances (HULIS) and two protein-like substances (PRLIS) with distinct oxidation states. Intense oxidation drove summer peaks of highly oxidized HULIS/PRLIS, with the contribution of oxidized PRLIS increasing from 10% (2020–2021) to 26% (2022). Principal Component Analysis (PCA) emphasized strengthened fossil-fuel emissions and ozone oxidation impacts in 2022, while Positive Matrix Factorization (PMF) modeling confirmed secondary processes as dominant DOM sources, with ozone oxidation accounting for 60.7% in 2022, inducing molecular condensation and fluorescence spectrum redshift. These findings advance understanding of wet-deposition DOM in megacities, clarify the dual influences of anthropogenic activities and environmental processes, and provide quantitative constraints to inform air quality management strategies in anthropogenically perturbed regions.
了解雨水溶解有机质（DOM）的组成、来源和转化对阐明地表-大气物质运移及其对生态系统的影响至关重要。这项为期三年（2020-2022）的杭州研究通过综合光谱和建模方法表征了人为影响的雨水DOM。结果表明，雨水化学成分中存在明显的人为影响，平均溶解有机碳（DOC）为2.9 mg cl - 1，次生离子占主导地位。2022年大流行后的经济复苏放大了化石燃料燃烧特征和硫酸盐的主导地位，同时DOC沉积通量增加了一倍（1.0克立方米毒血症（Iavorivska et al., 2016））。夏季DOC通量峰值为0.32 g C m-2，受降雨增加和二次过程的驱动。雨水DOM的光学指数FI、BIX和HIX分别为1.75±0.17、1.09±0.31和1.32±0.80，表明雨水DOM的腐殖化和老化程度较低，受人为和生物因素的影响。平行因子分析（PARAFAC）鉴定出两种腐殖质样物质（HULIS）和两种蛋白样物质（PRLIS）具有不同的氧化态。强烈氧化驱动了夏季高氧化的HULIS/PRLIS峰值，氧化PRLIS的贡献从10%（2020-2021）增加到26%（2022）。主成分分析（PCA）强调2022年化石燃料排放和臭氧氧化的影响增强，而正矩阵分解（PMF）模型证实次级过程是主要的DOM源，臭氧氧化在2022年占60.7%，引起分子缩聚和荧光光谱红移。这些发现促进了对特大城市湿沉降DOM的理解，阐明了人为活动和环境过程的双重影响，并为人为扰动地区的空气质量管理策略提供了定量约束。
{"title":"Pivotal role of oxidation processes in rainwater dissolved organic matter: A three-year study","authors":"Kaidi Li , Junjun Deng , Hao Ma , Ziye Huang , Zanfang Jin , Wei Hu , Libin Wu , Pingqing Fu","doi":"10.1016/j.wroa.2026.100494","DOIUrl":"10.1016/j.wroa.2026.100494","url":null,"abstract":"<div><div>Understanding the composition, sources, and transformation of rainwater dissolved organic matter (DOM) is critical for elucidating surface-atmosphere material transport and associated ecosystem impacts. This three-year (2020–2022) Hangzhou study characterized anthropogenically influenced rainwater DOM via integrated spectroscopic and modeling approaches. Results revealed strong anthropogenic imprints, with mean dissolved organic carbon (DOC) of 2.9 mg C L<sup>–1</sup> and secondary ions dominating rainwater chemistry. Post-pandemic economic recovery in 2022 amplified fossil-fuel-combustion signatures and sulfate dominance, alongside a doubled DOC deposition flux (1.0 g C m⁻ (Iavorivska et al., 2016)). Summer DOC flux peaked at 0.32 g C m<sup>–2</sup>, driven by increased rainfall and secondary processes. Rainwater DOM featured optical indices FI, BIX, and HIX of 1.75 ± 0.17, 1.09 ± 0.31, and 1.32 ± 0.80, indicating low humification and aging degrees with anthropogenic and biological contributions. Parallel Factor Analysis (PARAFAC) identified two humic-like substances (HULIS) and two protein-like substances (PRLIS) with distinct oxidation states. Intense oxidation drove summer peaks of highly oxidized HULIS/PRLIS, with the contribution of oxidized PRLIS increasing from 10% (2020–2021) to 26% (2022). Principal Component Analysis (PCA) emphasized strengthened fossil-fuel emissions and ozone oxidation impacts in 2022, while Positive Matrix Factorization (PMF) modeling confirmed secondary processes as dominant DOM sources, with ozone oxidation accounting for 60.7% in 2022, inducing molecular condensation and fluorescence spectrum redshift. These findings advance understanding of wet-deposition DOM in megacities, clarify the dual influences of anthropogenic activities and environmental processes, and provide quantitative constraints to inform air quality management strategies in anthropogenically perturbed regions.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100494"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100483
Talita Marinho , Stephan Berzio , Salahaldeen Dababat , Josivaldo Satiro , Alfredo Quirino , Konrad Koch , Mario T. Kato , Tito Gehring , Lourdinha Florencio , Marc Wichern
This study investigated the performance and nitrous oxide (N₂O) emission dynamics of algal-bacterial granular sludge (ABGS) cultivated in a 40 L sequencing batch photobioreactor (SBPBR) treating real domestic wastewater, without initial external inoculum. ABGS formation was successfully achieved and remained stable over 180 days, with stable granule structure (> 1000 µm), good settling properties (SVI₃₀ of 42 mL· gVSS⁻¹), and chlorophyll-a content of 1.2 ± 0.1 mg· gVSS⁻¹. The system remained resilient to disturbances, including tubifex proliferation, confirming the structural viability of ABGS under non-sterile conditions. Regarding treatment performance, the reactor achieved consistent COD removal (> 80 %) and efficient ammonium removal (> 97 %) after microbial community adaptation. However, phosphorus removal was moderate (52 %), limited by the lack of anaerobic cycling and absence of excess sludge removal. N2O dynamics were monitored under four operational scenarios: low/high dissolved oxygen (DO) (2–3 and 6–7 mg· L⁻¹) and with/without light. N₂O production on liquid phase was mainly influenced by DO concentration, as lower DO levels resulted in higher N₂O emissions, while light had only a minor effect on its dynamics. However, under high DO conditions (10 L· min⁻¹, kLa = 283 h⁻¹), N₂O in the gas phase (emission factor, EF) reached 3.4 %, which was considerably higher than under low DO (3 L· min⁻¹, kLa = 100 h⁻¹), where EF remained below 1 %. This outcome indicates that oxygen availability is the dominant driver of N₂O formation, with light exerting only a secondary influence. These results emphasize the dual control of N₂O by microbial pathways and physical mass transfer, underscoring the need to optimize aeration strategies in ABGS reactors to balance nitrogen removal and greenhouse gas mitigation.
{"title":"Domestic wastewater treatment in a 40 L photobioreactor without sludge inoculum: Process performance and insights into nitrous oxide dynamics","authors":"Talita Marinho , Stephan Berzio , Salahaldeen Dababat , Josivaldo Satiro , Alfredo Quirino , Konrad Koch , Mario T. Kato , Tito Gehring , Lourdinha Florencio , Marc Wichern","doi":"10.1016/j.wroa.2026.100483","DOIUrl":"10.1016/j.wroa.2026.100483","url":null,"abstract":"<div><div>This study investigated the performance and nitrous oxide (N₂O) emission dynamics of algal-bacterial granular sludge (ABGS) cultivated in a 40 L sequencing batch photobioreactor (SBPBR) treating real domestic wastewater, without initial external inoculum. ABGS formation was successfully achieved and remained stable over 180 days, with stable granule structure (> 1000 µm), good settling properties (SVI₃₀ of 42 mL· g<sub>VSS</sub>⁻¹), and chlorophyll-a content of 1.2 ± 0.1 mg· g<sub>VSS</sub>⁻¹. The system remained resilient to disturbances, including <em>tubifex</em> proliferation, confirming the structural viability of ABGS under non-sterile conditions. Regarding treatment performance, the reactor achieved consistent COD removal (> 80 %) and efficient ammonium removal (> 97 %) after microbial community adaptation. However, phosphorus removal was moderate (52 %), limited by the lack of anaerobic cycling and absence of excess sludge removal. N<sub>2</sub>O dynamics were monitored under four operational scenarios: low/high dissolved oxygen (DO) (2–3 and 6–7 mg· L⁻¹) and with/without light. N₂O production on liquid phase was mainly influenced by DO concentration, as lower DO levels resulted in higher N₂O emissions, while light had only a minor effect on its dynamics. However, under high DO conditions (10 L· min⁻¹, k<sub>L</sub>a = 283 h⁻¹), N₂O in the gas phase (emission factor, EF) reached 3.4 %, which was considerably higher than under low DO (3 L· min⁻¹, k<sub>L</sub>a = 100 h⁻¹), where EF remained below 1 %. This outcome indicates that oxygen availability is the dominant driver of N₂O formation, with light exerting only a secondary influence. These results emphasize the dual control of N₂O by microbial pathways and physical mass transfer, underscoring the need to optimize aeration strategies in ABGS reactors to balance nitrogen removal and greenhouse gas mitigation.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100483"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Pub Date : 2026-01-01DOI: 10.1016/j.wroa.2026.100500
Hyun-Ji Kang , Kyoung-Ho Kim , Kanghyun Park , Junseop Oh , Frankline Enow Arrey , Jeong-Woo Kim , Seong-Taek Yun
Intensive livestock farming in volcanic watersheds creates complex nitrogen pollution pathways that remain poorly understood. This study investigated nitrogen transport mechanisms in an ephemeral creek system on Jeju Island, South Korea, using an integrated approach combining hydrochemical analysis, dual isotope tracing, and microbial community profiling of 52 water samples from groundwater, springs, and surface runoff.
Results revealed a two-stage nitrogen pollution mechanism: during dry periods, manure-derived nitrogen underwent volatilization, creating accumulated nitrogen reservoirs with enriched δ15N signatures. Rainfall events subsequently triggered rapid mobilization of stored nitrogen through ephemeral creeks and subsurface pathways. Nitrate concentrations in spring water consistently exceeded Korean drinking water standard (44.4 mg/L NO3), with isotopic signatures confirming manure as the primary source. Dual isotope analysis demonstrated that microbial nitrification was the dominant transformation process, supported by key nitrifying bacteria (Acinetobacter, Comamonadaceae) along flow paths. Bayesian mixing models confirmed that runoff became the primary contributor to spring water nitrate during precipitation events. Advanced compositional data analysis validated the mixing of surface-derived nitrogen with groundwater. These findings highlight the vulnerability of spring water systems to delayed nitrogen inputs in fractured volcanic aquifers, emphasizing the need for management strategies that address both immediate and rainfall-triggered transport pathways in agricultural watersheds.
{"title":"Dual-phase nitrogen transport from swine farms in a volcanic watershed of Jeju Island, South Korea: Insights from hydrochemical, isotopic and microbial analyses","authors":"Hyun-Ji Kang , Kyoung-Ho Kim , Kanghyun Park , Junseop Oh , Frankline Enow Arrey , Jeong-Woo Kim , Seong-Taek Yun","doi":"10.1016/j.wroa.2026.100500","DOIUrl":"10.1016/j.wroa.2026.100500","url":null,"abstract":"<div><div>Intensive livestock farming in volcanic watersheds creates complex nitrogen pollution pathways that remain poorly understood. This study investigated nitrogen transport mechanisms in an ephemeral creek system on Jeju Island, South Korea, using an integrated approach combining hydrochemical analysis, dual isotope tracing, and microbial community profiling of 52 water samples from groundwater, springs, and surface runoff.</div><div>Results revealed a two-stage nitrogen pollution mechanism: during dry periods, manure-derived nitrogen underwent volatilization, creating accumulated nitrogen reservoirs with enriched δ<sup>15</sup>N signatures. Rainfall events subsequently triggered rapid mobilization of stored nitrogen through ephemeral creeks and subsurface pathways. Nitrate concentrations in spring water consistently exceeded Korean drinking water standard (44.4 mg/L NO<sub>3</sub>), with isotopic signatures confirming manure as the primary source. Dual isotope analysis demonstrated that microbial nitrification was the dominant transformation process, supported by key nitrifying bacteria (<em>Acinetobacter, Comamonadaceae</em>) along flow paths. Bayesian mixing models confirmed that runoff became the primary contributor to spring water nitrate during precipitation events. Advanced compositional data analysis validated the mixing of surface-derived nitrogen with groundwater. These findings highlight the vulnerability of spring water systems to delayed nitrogen inputs in fractured volcanic aquifers, emphasizing the need for management strategies that address both immediate and rainfall-triggered transport pathways in agricultural watersheds.</div></div>","PeriodicalId":52198,"journal":{"name":"Water Research X","volume":"30 ","pages":"Article 100500"},"PeriodicalIF":8.2,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
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