Journal of contaminant hydrology最新文献

{"title":"Microplastic contamination across trophic levels in a lowland spring watercourse of Northwestern Italy: New insights and biomonitoring implications","authors":"Marco Bertoli ,&nbsp;Paolo Pastorino ,&nbsp;Serena Anselmi ,&nbsp;Tecla Bentivoglio ,&nbsp;Giuseppe Esposito ,&nbsp;Giorgia Goriup ,&nbsp;Antonia Concetta Elia ,&nbsp;Marino Prearo ,&nbsp;Monia Renzi ,&nbsp;Elisabetta Pizzul","doi":"10.1016/j.jconhyd.2025.104726","DOIUrl":"10.1016/j.jconhyd.2025.104726","url":null,"abstract":"<div><div>Microplastic (MP) pollution is an emerging environmental threat, with freshwater ecosystems acting as both transport pathways and accumulation zones for these synthetic particles. Despite growing research, data on MP contamination in small, lowland spring watercourses remain scarce. This study investigates MP distribution in the Sacchetti Ditch, a lowland spring-fed stream in Northwestern Italy, through by-monthly sampling over one year, leading to insights about seasonal trends. MP occurrence was analyzed in water, sediment, and biotic compartments, including fish, macroinvertebrates, and bivalves. MP concentrations in water ranged from 27.2 ± 47.1 MP L⁻¹ (March) to 61.2 ± 20.4 MP L⁻¹ (May), while sediment levels peaked at 358.6 ± 224.1 MP kg⁻¹ in January. Fragments and fibers dominated across matrices, with black, red, and blue as the most common colors. Statistical analyses revealed no significant temporal trends, suggesting continuous MP inputs from untreated wastewater discharge, urban runoff, and industrial effluents. Biotic samples confirmed MP ingestion across trophic levels. <em>Gambusia affinis</em> and <em>Gammarus fossarum</em> exhibited the highest MP burdens in winter, while <em>Unio elongatulus</em> showed a strong correlation with waterborne MPs. Polymer analysis identified polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polyamide (PA), with PP showing significant selective ingestion by <em>U. elongatulus</em>. Non-Metric Multi-Dimensional Scaling (NMDS) analysis of seasonal MP content in both biotic and abiotic samples indicated no clear seasonal patterns across trophic levels, reinforcing the role of the ditch as a long-term MPs reservoir. These findings highlight the need for urgent mitigation measures to reduce persistent MP pollution in small freshwater ecosystems.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104726"},"PeriodicalIF":4.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047124","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 dissolved oxygen prediction model integrating ChatGPT expert knowledge-driven attention mechanism and normalization","authors":"Xiangfeng Bu ,&nbsp;Li Wang ,&nbsp;Xiaoyi Wang ,&nbsp;Jiping Xu ,&nbsp;Zhiyao Zhao ,&nbsp;Jiabin Yu ,&nbsp;Huiyan Zhang ,&nbsp;Qian Sun ,&nbsp;Yuting Bai","doi":"10.1016/j.jconhyd.2025.104718","DOIUrl":"10.1016/j.jconhyd.2025.104718","url":null,"abstract":"<div><div>Dissolved oxygen (DO) is a key indicator of surface water environmental conditions. However, methods for predicting DO concentrations based on historical data lack domain knowledge guidance, resulting in insufficient prediction accuracy. Therefore, this paper proposes a new DO prediction model (ChatGPT-EK-TabNet). First, an improved normalization method incorporating water quality domain knowledge is proposed. The maximum and minimum values of ChatGPT domain expert knowledge are used to replace sample extremes for normalization, mitigating the interference of outliers and inter-basin distribution differences on the scale. Second, a weighted feature constraint matrix based on ChatGPT domain expert knowledge is proposed and incorporated into the Scaled Dot Product Attention Mechanism to suppress unreasonable feature interactions in terms of knowledge. Finally, we improve the TabNet model while maintaining its sparse adaptive feature selection. Experimental results show that under the Miyun Reservoir data in Beijing, the model performance is <span><math><mi>RMSE</mi></math></span>=0.3349, <span><math><mi>MAE</mi></math></span>=0.2101, and <span><math><msup><mi>R</mi><mn>2</mn></msup></math></span>=0.9388. Additionally, compared to the DO prediction model without incorporating water quality domain knowledge, the proposed model reduces <span><math><mi>RMSE</mi></math></span> and <span><math><mi>MAE</mi></math></span> by 0.1222 and 0.2187, respectively, and improves <span><math><msup><mi>R</mi><mn>2</mn></msup></math></span> by 0.1120. Generalization experiments demonstrate that the proposed model achieves excellent prediction performance on the Xiaoxingkai Lake, Ussuri River, and Muling River datasets. Reliability validation further indicates that ChatGPT-derived domain expert knowledge achieves higher numerical accuracy than data-driven correlation matrices. Its fine-grained representation and cross-domain generalization match or even exceed those of theoretical expert methods. The proposed approach supports sustainable management of surface water environments and can be extended to other water bodies and water-quality indicators.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104718"},"PeriodicalIF":4.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060706","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":"Occurrence, distribution, and risk assessment of antibiotics in post-harvest and drained ponds of Sheyang River estuary in Jiangsu Province: Implications for sustainable aquaculture management","authors":"Wenqian Shan ,&nbsp;Shiya Gu ,&nbsp;Wangrong Cui ,&nbsp;Xinyun Feng ,&nbsp;Xin Song ,&nbsp;Jianwei Dong ,&nbsp;Hui Xie ,&nbsp;Da Li","doi":"10.1016/j.jconhyd.2025.104720","DOIUrl":"10.1016/j.jconhyd.2025.104720","url":null,"abstract":"<div><div>Antibiotic contamination in aquaculture has long been a critical problem, jeopardizing aquatic ecosystems, food security, and human health. However, the post-harvest antibiotic residues in drained ponds, critical for guiding subsequent farming cycles, remain poorly understood. This study systematically investigated 20 target antibiotics in white shrimp aquaculture ponds at the Sheyang Estuary, Jiangsu Province, China, focusing on sediments and the low-lying area residual water sampled three months after harvest and drainage. Sixteen antibiotics were detected in residual water at total concentrations ranging from 19.3 ng/L to 28.4 ng/L and ten antibiotics were detected in sediments at total concentrations ranging from 9.49 ng/g to 65.9 ng/g. Tetracyclines (TCs) were the dominant antibiotic class, with chlortetracycline (CTC) prevalent in water and doxycycline (DXC) dominant in sediments. Notably, prohibited antibiotics were detected, with ofloxacin (OFX) posing medium ecological risk. Furthermore, 80 % of ponds showed medium ecological risk from antibiotic mixtures. Ciprofloxacin (CLX) was identified as the sole priority antibiotic posing both ecological and resistance risks. Rewatering ponds for subsequent cycles may trigger sediment-water exchange, remobilizing sediment-bound antibiotics into the water column. In this study, pre-cycle sediment screening is proposed to quantify residual antibiotic levels. Adaptive dosing strategies should prioritize reducing inputs of antibiotics exhibiting significant residual concentrations from previous cycles. This research, focusing on post-drainage residues in a typical estuarine aquaculture area, provides novel scientific guidance for sustainable antibiotic use and supports the long-term health of aquaculture systems.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104720"},"PeriodicalIF":4.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145080541","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":"Porous hydroxyapatite synthesized from discarded oyster shells via pseudomorphic replacement: A novel adsorbent for humic acid removal","authors":"Jianan Guo ,&nbsp;Xinying Zhang ,&nbsp;Lina Chen ,&nbsp;Sudan Chen ,&nbsp;Heshan Lv ,&nbsp;Yaran Song","doi":"10.1016/j.jconhyd.2025.104719","DOIUrl":"10.1016/j.jconhyd.2025.104719","url":null,"abstract":"<div><div>Humic acid (HA) is a major precursor to harmful disinfection by-products in water treatment systems. While hydroxyapatite (HAP) is a promising adsorbent for HA removal, its practical application is often limited by nanoparticle aggregation, which hinders separation and filtration. To overcome this challenge, this study presents a novel method to synthesize a structured, porous HAP adsorbent (OSPP) via a simple pseudomorphic replacement reaction using waste oyster shells as a template. The resulting OSPP exhibited a specific surface area of 55.7 m²/g, an 11.2-fold increase over the original oyster shell powder (OSP, 4.97 m²/g). This enhanced structure led to superior performance in both batch and continuous-flow systems. In batch experiments, OSPP's HA adsorption capacity was 18.04 mg C/g, 2.9 times higher than that of OSP (6.13 mg C/g). More significantly, in fixed-bed column experiments with real surface water, OSPP achieved a practical capacity of 4.48 mg C/g, outperforming OSP (0.22 mg C/g) by a factor of 20.4. Spectroscopic analysis indicated that HA adsorption was driven by a combination of electrostatic attraction and surface complexation. This work demonstrates an approach to upcycling biowaste into a highly effective adsorbent for water remediation, offering a sustainable solution for both waste management and water purification.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104719"},"PeriodicalIF":4.4,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145109786","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":"Divergence in anthropogenic activities contributed to the eutrophication heterogeneity between river and lake at basin scale: new insights from trophic state index in Asia's largest basin (Yangtze River)","authors":"Yan Dai ,&nbsp;Xihua Wang ,&nbsp;Y. Jun Xu ,&nbsp;Qinya Lv ,&nbsp;Xuming Ji ,&nbsp;Boyang Mao ,&nbsp;Shunqing Jia ,&nbsp;Zejun Liu ,&nbsp;Chengming Luo ,&nbsp;Yanxin Rong","doi":"10.1016/j.jconhyd.2025.104717","DOIUrl":"10.1016/j.jconhyd.2025.104717","url":null,"abstract":"<div><div>Eutrophication caused by excessive nutrient inputs from intense anthropogenic activities seriously threatens the ecological health of river and lake systems worldwide. However, previous eutrophication studies have focused mostly on lakes, with little attention paid to rivers, and the anthropogenic driving mechanisms of eutrophication heterogeneity between rivers and lakes within large-scale basins remain unclear. In this study, the seasonal and regional characteristics of eutrophication in rivers and lakes within the Yangtze River Basin were analyzed from 2021 to 2023. The relationship between anthropogenic activities and the eutrophication heterogeneity between rivers and lakes was determined by considering population and land use factors. The results showed that the eutrophication of both rivers and lakes was more severe in the downstream area than upstream and midstream area, and intensified during the wet season compared to the normal and dry seasons. On average, 63.2 % and 20.7 % of the river stations were at eutrophic and meso-eutrophic states, respectively; and an average of 26.3 % and 44.2 % of lake stations were at eutrophic and meso-eutrophic states, respectively. Correlation analysis revealed significant differences in human-driven eutrophication mechanisms between rivers and lakes. The trophic states of river systems acutely reflected short-term anthropogenic pressures, while lake systems predominantly manifest the long-term cumulative effects of nutrients generated by land use within the watershed. This study can provide reliable support for targeted management of eutrophication in different water bodies in large-scale basins.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104717"},"PeriodicalIF":4.4,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026329","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":"Oxidative dissolution of nano- and microparticles of lead in water","authors":"Gennadii L. Bykov,&nbsp;Vadim A. Ershov,&nbsp;Boris G. Ershov","doi":"10.1016/j.jconhyd.2025.104709","DOIUrl":"10.1016/j.jconhyd.2025.104709","url":null,"abstract":"<div><div>Lead is an extremely hazardous pollutant that poses a severe threat to the ecosystem. It enters the atmosphere in the form of nano- and microparticles and is then carried by wind and water. These particles easily dissolve in water, turning into ions which are easily absorbed by living organisms. Thus, lead quickly spreads throughout the environment, harming the ecosystem. This paper explores the state and transformation of nano- and microparticles of lead, focusing on the formation and properties of their dispersions in water, both deaerated and aerated. In deaerated water, the metal dispersion is unstable; microparticles agglomerate and eventually settle. When exposed to air, lead microparticles undergo rapid oxidation and dissolution. Oxidative dissolution accelerates with increasing acidity. The dissolution process follows an electrochemical mechanism: first, a poorly soluble oxide forms, which then reacts with hydrogen ions to dissolve. The calculated activation energy for the oxidative dissolution of lead microparticles in water is 41.6 ± 3.1 kJ mol⁻¹.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104709"},"PeriodicalIF":4.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005153","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":"Modeling the fate of engineered titanium dioxide nanoparticles from an industrial effluent to a river","authors":"Raphael di Chiara Roupert ,&nbsp;Gaetana Quaranta ,&nbsp;Véronique Adam ,&nbsp;Philippe Ackerer ,&nbsp;Stéphanie Loyaux-Lawniczak","doi":"10.1016/j.jconhyd.2025.104705","DOIUrl":"10.1016/j.jconhyd.2025.104705","url":null,"abstract":"<div><div>Understanding the environmental fate of engineered titanium dioxide nanoparticles (TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> NPs) is essential due to their increasing industrial use and potential ecological risks. This study presents <span>SAPaTin</span> (<strong>S</strong>moluchowski <strong>A</strong>ggregation of nano-<strong>Pa</strong>rticle of <strong>Ti</strong>ta<strong>n</strong>ium), a mechanistic modeling framework based on Smoluchowski aggregation kinetics, to simulate the transport and transformation of TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> NPs discharged from an industrial effluent into a river system. The model integrates experimental data and field observations to account for the spatial variability in water chemistry, particle size distribution, and aggregation behavior. Results show that while the fractal dimension of aggregates (<span><math><mrow><msub><mrow><mi>D</mi></mrow><mrow><mi>f</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>5</mn></mrow></math></span> or 2.3) does not affect the initial size distribution at the pipe inlet due to the dominance of Brownian motion, it significantly influences the concentration of particles within size classes. In the river, heteroaggregation between TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> NPs and suspended particulate matter (SPM) is found to be primarily driven by differential settling rather than Brownian or shear-induced collisions. The residence time of aggregates in the river exponentially increases the fraction of sedimented heteroaggregates, a process controlled largely by SPM density. This study highlights the critical role of heteroaggregation and aggregate structure in predicting nanoparticle behavior in fluvial environments and offers a validated modeling tool for environmental risk assessment of nano-enabled industrial discharges.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104705"},"PeriodicalIF":4.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145080320","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":"Enhanced effect and mechanism of biochar on the nitrogen removal of low C/N wastewater by cold-tolerant heterotrophic nitrifying–aerobic denitrifying bacterium","authors":"Xiaoyu Li,&nbsp;Meizhen Tang,&nbsp;Jie Jiang,&nbsp;Shiqiang Ma,&nbsp;Shumin Yao,&nbsp;Yuewei Yang","doi":"10.1016/j.jconhyd.2025.104708","DOIUrl":"10.1016/j.jconhyd.2025.104708","url":null,"abstract":"<div><div>Biological denitrification is an essential method for sewage treatment, though its efficiency is often constrained by low temperatures and insufficient organic carbon sources. In this study, a novel cold-tolerant heterotrophic nitrification–aerobic denitrification bacterium, <em>Pseudomonas fluorescens</em> sp. Z03, was isolated from activated sludge, and its denitrification performance was evaluated. Meanwhile the effect and mechanism of biochar in enhancing denitrification of low C/N wastewater by <em>P. fluorescens</em> Z03 were also investigated. The results showed that <em>P. fluorescens</em> Z03 effectively removed various nitrogen species at 10 °C, with maximum removal rates of ammonia, nitrite, and nitrate being 1.75 mg/(L·h), 1.63 mg/(L·h), and 1.67 mg/(L·h), respectively. The NH₄⁺-N removal efficiency of Z03 was significant enhanced by 3:1 mixed biochar, reaching 92.79 % at 48 h, which was 66.18 % higher than that of R_CK. The reason for this can be attributed to the mixed biochar combined the beneficial properties of both BC400 and BC700, including a large surface area and pore size, a high concentration of active functional groups, a relatively high dissolved organic carbon content, and favorable oxidation-reduction potential. Therefore, R_M31 exhibited the most significant enhancement, and the NH₄⁺-N removal efficiency was 92.79 % at 48 h, which was 66.18 % and 8.55 % - 35.78 % higher than that of R_CK and other biochar groups. In addition, the 3:1 mixed biochar coupled with <em>P. fluorescens</em> Z03 has a long – term and high - efficiency effect on improving the nitrogen removal efficiency of piggery sewage. These findings highlight the potential of combining 3:1 mixed biochar with <em>P. fluorescens</em> Z03 for the treatment of low C/N wastewater at low temperatures. These findings have confirmed the feasibility of using 3:1 mixed biochar combined strain Z03 for low C/N wastewater treatment at low temperature, and have important practical significance.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104708"},"PeriodicalIF":4.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020300","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 non–equilibrium effects (DNEs) of imbibition processes in an air-water two-phase fine sandy medium- a laboratory-scale experimental study","authors":"Yuhao Ai ,&nbsp;Lihua Yang ,&nbsp;Yijia Sun ,&nbsp;Xiaoyi Wu ,&nbsp;Jingya Xi ,&nbsp;Hongfan Hou ,&nbsp;Yihang Yang ,&nbsp;Pengfei Wu ,&nbsp;Yan Li","doi":"10.1016/j.jconhyd.2025.104707","DOIUrl":"10.1016/j.jconhyd.2025.104707","url":null,"abstract":"<div><div>We systematically investigated DNEs throughout imbibition processes, specifically evaluating: (1) the temporal correspondence between DNE development and changes in water saturation/capillary pressure, and (2) the dominant factors governing DNE magnitude during imbibition. The signal drift during extended testing, and the gravitational effect on both the capillary pressure and water saturation were eliminated. The results indicate that, when water saturation was below a threshold value (∼0.43), the maximum difference between static and dynamic capillary pressures (DPMAX) occurred first, followed sequentially by: the maximum rate of water saturation change over time (RSMAX), minimum capillary pressure in an imbibition step (PMIN), and maximum water saturation (SMAX). In subsequent imbibition steps, this sequence shifted to: RSMAX, DPMAX, PMIN, and SMAX. For smooth imbibition processes, the order of events was: RSMAX, SMAX, PMIN and DPMAX (occurring nearly simultaneously). The imbibition process demonstrated no systematic correlation between the extremum values of capillary pressure (PMIN), water saturation (SMAX), and their respective derivatives (DPMAX, RSMAX). Lag times between consecutive parameter pairs (DPMAX, RSMAX, PMIN, and SMAX) exhibited decreasing trends as the water saturation change rate (<em>ΔSw/Δt</em>) increased. Therefore, in stepwise imbibition processes, DNEs are primarily characterized by: (1) the lag time between initial response points of capillary pressure and water saturation (<em>Δt₁</em>), (2) the lag time between PMIN and SMAX (<em>Δt₂</em>), (3) DPMAX, and (4) the dynamic coefficient <em>τ</em> (<span><span>Hassanizadeh and Gray, 1990</span></span>). While <em>Δt₁</em> and <em>Δt₂</em> are clearly observable in both stepwise and smooth imbibition processes, they become negligible above 0.43 water saturation. Notably, the maximum dynamic effect (DPMAX) increased with increasing water saturation while τ decreased with increasing water saturation. Furthermore, results confirmed that DNE magnitudes correlated more strongly with water saturation and its rate of change (<em>ΔSw/Δt</em>) than with capillary number, consistent with previous findings. Lag times (<em>Δt₁, Δt₂</em>), τ, and DPMAX constitute meaningful quantitative parameters for characterizing DNEs in stepwise imbibition processes.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"276 ","pages":"Article 104707"},"PeriodicalIF":4.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005154","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":"Unraveling nitrogen evolution characteristics and driving mechanisms of estuarine alluvial islands","authors":"Xihua Wang ,&nbsp;Yanxin Rong ,&nbsp;Y. Jun Xu ,&nbsp;Qinya lv ,&nbsp;Xuming Ji ,&nbsp;Boyang Mao ,&nbsp;Shunqing Jia ,&nbsp;Zejun Liu ,&nbsp;Chengming Luo ,&nbsp;Yan Dai","doi":"10.1016/j.jconhyd.2025.104706","DOIUrl":"10.1016/j.jconhyd.2025.104706","url":null,"abstract":"<div><div>Nitrogen pollution has long been a major threat to river and estuarine ecosystems around the world. However, at present, most of the research focuses on rivers and attached freshwater lakes, and the research on the nitrogen evolution characteristics and driving mechanisms of estuarine alluvial islands at river estuaries remains poorly understood. In this study, four cross-sections in Chongming District from 2021 to 2023, including Qixiaogang West Bridge, Qianweicun Bridge, Wuxiao, and Sanshahong Intersection were Sampled. Using Pearson correlation analysis, regression analysis and other methods to explore the correlation and trend of water quality indicators, and then reveal the spatiotemporal changes of nitrogen and its influencing factors. Our results showed that the statistical analysis revealed no significant fluctuations in ammonia nitrogen (NH₄⁺) and total nitrogen (TN) during the study period; specifically (NH₄⁺ reached 0.65 mg/L in June, while TN reached 4.36 mg/L in December). Correlation analysis revealed a negative correlation between TN, NH₄⁺, and pH, a positive correlation with dissolved oxygen (DO), and notable correlations between NH₄⁺ and turbidity and electric conductivity (EC). In addition, natural factors (rainfall) and human activities were important factors affecting nitrogen, with agricultural cultivation leading to a reduction of 78.92 km² in the study area. These results will help reveal the characteristics and driving mechanisms of nitrogen concentration in estuarine alluvial islands, propose targeted measures for future water pollution control, and provide valuable references for similar studies.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"275 ","pages":"Article 104706"},"PeriodicalIF":4.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988063","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}