<div><div>Widespread dissemination of antibiotic resistance genes (ARGs) in the aquatic environment has become a concern for public health. This study evaluated the performance of UV light emitting diodes (UV-LEDs) based advanced oxidation processes (AOPs) such as the simultaneous application of UV-LEDs (265 and 285 nm) and oxidants (chlorine and persulfate) to degrade ARGs. Persulfate (PS)-based treatment systems showed lower log-removals than chlorine (Cl<sub>2</sub>) to degrade extracellular ARGs (e-ARGs), with the molar absorption coefficients (ɛ) for PS being 13.66 and 66.4 times lower than those for chlorine at 265 nm and 285 nm, respectively. While 285/Cl<sub>2</sub> exhibited stronger synergistic effects achieving an optimal synergy value of 4.02 log, 265/Cl<sub>2</sub> displayed better degradation rates with the maximum degradation rate of 0.117 cm<sup>2</sup>/mJ. Degradation rates induced by 265/PS were 1.2 to 2.2 times higher than 285/PS across all applied concentrations of oxidants. 265/PS also demonstrated a more pronounced synergistic effect than 285/PS with an optimal synergy value of 2.56. Quantum yields (Φ) at 265 nm are ∼1.1 times higher than at 285 nm for both oxidants. Cl<sub>2</sub> has ∼1.7 times higher ɛ-value at 285 nm than at 265 nm, while persulfate's ɛ-value is ∼2.93 times higher at 265 nm than at 285 nm. Thus, the better ɛ-value of Cl<sub>2</sub> at 285 nm improved the performance of 285/Cl<sub>2</sub> over 285/PS than 265 nm-based AOPs. Radical roles were investigated using scavenger studies with nitrobenzene (NB) and ethanol (EtOH) as quenchers. EtOH reacts quickly with hydroxyl radical (HO·), reactive chlorine species (RCS), and sulfate radical (SO<sub>4</sub>·‾), while NB primarily reacts with HO· and shows minimal reactivity with other radicals. The involvement of radicals in different AOPs varied depending on the wavelength. For 265/Cl<sub>2</sub> and 285/PS, HO· was the primary contributor, with minimal contributions from other radicals. Significant contributions from RCS and SO<sub>4</sub>·‾ radicals were observed for 285/Cl<sub>2</sub> and 265/PS, respectively, alongside HO·. Plasmid linearization was observed when the plasmid was subjected to AOPs, confirming the role of radicals in initiating the process of plasmid linearization through their interaction with the sugar-phosphate backbone. Scavenging of radicals by cellular components diminished the synergistic impact of AOPs on intracellular ARGs (i-ARGs) degradation. While AOPs demonstrated a notable degradation of extracellular polymeric substances (EPS), the absence of EPS didn't enhance the degradation of i-ARGs. The overall concentration of free ARGs (f-ARGs) was influenced by the interplay of two factors: the extent of membrane damage and the efficacy of e-ARG degradation. This study offers detailed insights into the effectiveness and mechanisms of UV-LED based AOPs for inactivating various forms of ARGs, as well as the associated challenges. Understan
{"title":"The efficacies of degrading antibiotic resistance genes (ARGs) by applying UV light emitting diodes (UV-LEDs) based advanced oxidation processes (AOPs)","authors":"Shayok Ghosh , Guanghan Zhang , Yiwei Chen , Jiangyong Hu","doi":"10.1016/j.watres.2025.123197","DOIUrl":"10.1016/j.watres.2025.123197","url":null,"abstract":"<div><div>Widespread dissemination of antibiotic resistance genes (ARGs) in the aquatic environment has become a concern for public health. This study evaluated the performance of UV light emitting diodes (UV-LEDs) based advanced oxidation processes (AOPs) such as the simultaneous application of UV-LEDs (265 and 285 nm) and oxidants (chlorine and persulfate) to degrade ARGs. Persulfate (PS)-based treatment systems showed lower log-removals than chlorine (Cl<sub>2</sub>) to degrade extracellular ARGs (e-ARGs), with the molar absorption coefficients (ɛ) for PS being 13.66 and 66.4 times lower than those for chlorine at 265 nm and 285 nm, respectively. While 285/Cl<sub>2</sub> exhibited stronger synergistic effects achieving an optimal synergy value of 4.02 log, 265/Cl<sub>2</sub> displayed better degradation rates with the maximum degradation rate of 0.117 cm<sup>2</sup>/mJ. Degradation rates induced by 265/PS were 1.2 to 2.2 times higher than 285/PS across all applied concentrations of oxidants. 265/PS also demonstrated a more pronounced synergistic effect than 285/PS with an optimal synergy value of 2.56. Quantum yields (Φ) at 265 nm are ∼1.1 times higher than at 285 nm for both oxidants. Cl<sub>2</sub> has ∼1.7 times higher ɛ-value at 285 nm than at 265 nm, while persulfate's ɛ-value is ∼2.93 times higher at 265 nm than at 285 nm. Thus, the better ɛ-value of Cl<sub>2</sub> at 285 nm improved the performance of 285/Cl<sub>2</sub> over 285/PS than 265 nm-based AOPs. Radical roles were investigated using scavenger studies with nitrobenzene (NB) and ethanol (EtOH) as quenchers. EtOH reacts quickly with hydroxyl radical (HO·), reactive chlorine species (RCS), and sulfate radical (SO<sub>4</sub>·‾), while NB primarily reacts with HO· and shows minimal reactivity with other radicals. The involvement of radicals in different AOPs varied depending on the wavelength. For 265/Cl<sub>2</sub> and 285/PS, HO· was the primary contributor, with minimal contributions from other radicals. Significant contributions from RCS and SO<sub>4</sub>·‾ radicals were observed for 285/Cl<sub>2</sub> and 265/PS, respectively, alongside HO·. Plasmid linearization was observed when the plasmid was subjected to AOPs, confirming the role of radicals in initiating the process of plasmid linearization through their interaction with the sugar-phosphate backbone. Scavenging of radicals by cellular components diminished the synergistic impact of AOPs on intracellular ARGs (i-ARGs) degradation. While AOPs demonstrated a notable degradation of extracellular polymeric substances (EPS), the absence of EPS didn't enhance the degradation of i-ARGs. The overall concentration of free ARGs (f-ARGs) was influenced by the interplay of two factors: the extent of membrane damage and the efficacy of e-ARG degradation. This study offers detailed insights into the effectiveness and mechanisms of UV-LED based AOPs for inactivating various forms of ARGs, as well as the associated challenges. Understan","PeriodicalId":443,"journal":{"name":"Water Research","volume":"276 ","pages":"Article 123197"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.watres.2025.123207
Yussi M. Palacios Delgado , Maghfira Saifuddaolah , Rebekah Henry , Kerrie Burge , David Thomas McCarthy , S. Fiona Barker , Christelle Schang , Vinaina Waqa , Brandon Winfrey , Karin Leder
Quantification of faecal indicator organism (FIO) is essential for surveillance monitoring, performance compliance and public health interventions. IDEXX's automated FIO detection technique, TECTATM, and IDEXX Colilert offer greater efficiency than traditional methods but have not been critically compared across diverse levels of faecal contamination or evaluated against key practical requirements and cost factors. This study compared the use of IDEXX Colilert and TECTA™ for measuring indicative contamination in 785 samples from drinking water, wells, surface water, greywater and a constructed wetland system, collected from Fijian and Indonesian informal settlements. Both methods ranked sample types in the same order in terms of indicative faecal contamination, and at Escherichia coli (E. coli) concentrations between <1–105 CFU or MPN/100 mL (municipal, shallow and deep well samples), both methods were highly correlated. However, at 102–109 CFU/100 mL (TECTA™) or 102–106 MPN/100 mL (IDEXX Colilert) E. coli (surface water samples), a moderate positive correlation was observed (R = 0.56, p = 2.2−13), and a high proportion of samples exceeded the detection limit of the IDEXX Colilert method. Greywater and septic tank samples exhibited total coliform mean values greater than 106 CFU/100 mL, with no correlation between IDEXX Colilert and TECTA™ results. TECTA™ required only one dilution for returning specific E. coli values, ideal for performance compliance and faecal contamination assessments, while IDEXX Colilert often needed two levels of dilution. For surveillance purposes, IDEXX Colilert may be more cost-effective given the higher initial setup costs of TECTA™; however, TECTA™’s faster turnaround times and automated results may offset expenses. This study presents a versatile decision analysis that enables laboratories worldwide to customise method comparisons based on their unique requirements, driving more effective implementation and global standardisation of these methods.
{"title":"Evaluating analytical approaches for smarter decision-making in faecal contamination monitoring and assessment","authors":"Yussi M. Palacios Delgado , Maghfira Saifuddaolah , Rebekah Henry , Kerrie Burge , David Thomas McCarthy , S. Fiona Barker , Christelle Schang , Vinaina Waqa , Brandon Winfrey , Karin Leder","doi":"10.1016/j.watres.2025.123207","DOIUrl":"10.1016/j.watres.2025.123207","url":null,"abstract":"<div><div>Quantification of faecal indicator organism (FIO) is essential for surveillance monitoring, performance compliance and public health interventions. IDEXX's automated FIO detection technique, TECTA<sup>TM</sup>, and IDEXX Colilert offer greater efficiency than traditional methods but have not been critically compared across diverse levels of faecal contamination or evaluated against key practical requirements and cost factors. This study compared the use of IDEXX Colilert and TECTA™ for measuring indicative contamination in 785 samples from drinking water, wells, surface water, greywater and a constructed wetland system, collected from Fijian and Indonesian informal settlements. Both methods ranked sample types in the same order in terms of indicative faecal contamination, and at <em>Escherichia coli</em> (<em>E. coli</em>) concentrations between <1–10<sup>5</sup> CFU or MPN/100 mL (municipal, shallow and deep well samples), both methods were highly correlated. However, at 10<sup>2</sup>–10<sup>9</sup> CFU/100 mL (TECTA™) or 10<sup>2</sup>–10<sup>6</sup> MPN/100 mL (IDEXX Colilert) <em>E. coli</em> (surface water samples), a moderate positive correlation was observed (<em>R</em> = 0.56, <em>p</em> = 2.2<sup>−13</sup>), and a high proportion of samples exceeded the detection limit of the IDEXX Colilert method. Greywater and septic tank samples exhibited total coliform mean values greater than 10<sup>6</sup> CFU/100 mL, with no correlation between IDEXX Colilert and TECTA™ results. TECTA™ required only one dilution for returning specific <em>E. coli</em> values, ideal for performance compliance and faecal contamination assessments, while IDEXX Colilert often needed two levels of dilution. For surveillance purposes, IDEXX Colilert may be more cost-effective given the higher initial setup costs of TECTA™; however, TECTA™’s faster turnaround times and automated results may offset expenses. This study presents a versatile decision analysis that enables laboratories worldwide to customise method comparisons based on their unique requirements, driving more effective implementation and global standardisation of these methods.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123207"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1016/j.watres.2025.123198
Zhiqin Jiang , Yanan Liang , Shu Zhu , Kai Zheng , Yingjie Zhu , Danhui Yang , Hualin Wang , Pengbo Fu
The challenges faced by sludge pyrolysis units, including poor heat transfer efficiency and uneven heating of material groups, significantly hinder the green and low-carbon transformation and sustainable development of sludge treatment. The suspension self-rotation of sludge particles in a cyclone enhances particle heat transfer, thereby improving the pyrolysis process. In this study, we developed a novel method for sludge pyrolysis using Cyclone Suspension Self-Rotation Pyrolysis Reactor (CSSPR). Through numerical simulation and high-speed camera visualization, we analyzed the effects of cyclone cone angle, particle size, and inlet flow rate on particle suspension self-rotation. A systematic investigation was conducted into the mechanisms by which “particle suspension self-rotation” enhances “sludge particle pyrolysis”. Consequently, an effective method for utilizing hydrogen-rich gas produced by sludge suspension self-rotation pyrolysis was developed. The results showed that CSSPR with a 9° cone angle achieved optimal suspension autorotation efficiency. Under optimal conditions—sludge particle moisture content of 31.89% and particle suspension rotation rate of 100%, the hydrogen production per unit of sludge reached up to 265.78 mL/g, which is 1.3 times higher than that produced in a static state. Compared to traditional fixed-bed pyrolysis technology, CSSPR demonstrated superior pyrolysis performance, achieving a 155.78 mL/g higher hydrogen yield per unit of sludge. This study offers a novel approach to developing sludge resource pyrolysis technology, thereby providing an effective pathway for addressing climate change and advancing environmental governance.
{"title":"Hydrogen production by suspension self-rotation enhanced pyrolysis of sludge particles in cyclone","authors":"Zhiqin Jiang , Yanan Liang , Shu Zhu , Kai Zheng , Yingjie Zhu , Danhui Yang , Hualin Wang , Pengbo Fu","doi":"10.1016/j.watres.2025.123198","DOIUrl":"10.1016/j.watres.2025.123198","url":null,"abstract":"<div><div>The challenges faced by sludge pyrolysis units, including poor heat transfer efficiency and uneven heating of material groups, significantly hinder the green and low-carbon transformation and sustainable development of sludge treatment. The suspension self-rotation of sludge particles in a cyclone enhances particle heat transfer, thereby improving the pyrolysis process. In this study, we developed a novel method for sludge pyrolysis using Cyclone Suspension Self-Rotation Pyrolysis Reactor (CSSPR). Through numerical simulation and high-speed camera visualization, we analyzed the effects of cyclone cone angle, particle size, and inlet flow rate on particle suspension self-rotation. A systematic investigation was conducted into the mechanisms by which “particle suspension self-rotation” enhances “sludge particle pyrolysis”. Consequently, an effective method for utilizing hydrogen-rich gas produced by sludge suspension self-rotation pyrolysis was developed. The results showed that CSSPR with a 9° cone angle achieved optimal suspension autorotation efficiency. Under optimal conditions—sludge particle moisture content of 31.89% and particle suspension rotation rate of 100%, the hydrogen production per unit of sludge reached up to 265.78 mL/g, which is 1.3 times higher than that produced in a static state. Compared to traditional fixed-bed pyrolysis technology, CSSPR demonstrated superior pyrolysis performance, achieving a 155.78 mL/g higher hydrogen yield per unit of sludge. This study offers a novel approach to developing sludge resource pyrolysis technology, thereby providing an effective pathway for addressing climate change and advancing environmental governance.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123198"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-27DOI: 10.1016/j.watres.2025.123191
Run Su , Litong Shi , Yan Wei , Bin Ma
Nitrification is a central process in the global nitrogen cycle, yet the ecological niches and growth strategies of ammonia-oxidizing microorganisms in oligotrophic environments remain poorly understood. To investigate the ecological responses of complete ammonia oxidizers (Comammox) and ammonia-oxidizing archaea (AOA), a membrane bioreactor (MBR) system with two distinct ammonia loading rates (ALRs) was employed in this study. Metagenomic and meta-transcriptomic analyses showed that Comammox species—including Candidatus Nitrospira nitrosa and Candidatus Nitrospira inopinata—underwent a pronounced “bloom” only at high ALR, where their DNA and mRNA relative abundances reached 4.7 % and 5.63 %, respectively. Meanwhile, AOA steadily increased under both high and low ALR in oligotrophic environments. Network analysis further indicated stronger cooperative interactions between Comammox and AOA in higher ALR, highlighting distinct ecological strategies that underpin ammonia oxidation in oligotrophic environments. These findings not only support the development of low-carbon nitrogen removal processes in wastewater treatment but also clarify the impact of nitrogen loading on the distribution of ammonia-oxidizing microorganisms in natural ecosystems and provide insights into the origin and evolutionary pathways of these essential microbes.
{"title":"Comammox and AOA responses to ammonia loading rate in oligotrophic environments","authors":"Run Su , Litong Shi , Yan Wei , Bin Ma","doi":"10.1016/j.watres.2025.123191","DOIUrl":"10.1016/j.watres.2025.123191","url":null,"abstract":"<div><div>Nitrification is a central process in the global nitrogen cycle, yet the ecological niches and growth strategies of ammonia-oxidizing microorganisms in oligotrophic environments remain poorly understood. To investigate the ecological responses of complete ammonia oxidizers (Comammox) and ammonia-oxidizing archaea (AOA), a membrane bioreactor (MBR) system with two distinct ammonia loading rates (ALRs) was employed in this study. Metagenomic and meta-transcriptomic analyses showed that Comammox species—including <em>Candidatus Nitrospira nitrosa</em> and <em>Candidatus Nitrospira inopinata</em>—underwent a pronounced “bloom” only at high ALR, where their DNA and mRNA relative abundances reached 4.7 % and 5.63 %, respectively. Meanwhile, AOA steadily increased under both high and low ALR in oligotrophic environments. Network analysis further indicated stronger cooperative interactions between Comammox and AOA in higher ALR, highlighting distinct ecological strategies that underpin ammonia oxidation in oligotrophic environments. These findings not only support the development of low-carbon nitrogen removal processes in wastewater treatment but also clarify the impact of nitrogen loading on the distribution of ammonia-oxidizing microorganisms in natural ecosystems and provide insights into the origin and evolutionary pathways of these essential microbes.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123191"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-27DOI: 10.1016/j.watres.2025.123193
Yang Wang , Ziyuan Huang , Zhang Yan , Zhenchao Lei , Huanxin Ma , Chunhua Feng
Acid mine drainage (AMD) is characterized by high concentrations of Fe(II) and Fe(III), which can be harnessed for the in-situ formation of schwertmannite, enabling the efficient immobilization of toxic heavy metals. However, existing biological and chemical methods for schwertmannite synthesis face significant challenges, including low Fe(II) oxidation rates and particularly limited Fe(III) precipitation efficiency in acidic environments. In this study, we develop a visible light-assisted photo-electrochemical (PEC) system that effectively overcomes these barriers. By leveraging anodically evolved O2 and cathodically generated OH−, we achieved facile Fe(II) oxidation at pH 3.0, and an impressive Fe(III) precipitation efficiency of 82.8 %, significantly exceeding the < 30 % efficiency reported by other methods. Mössbauer spectroscopy and X-ray diffraction confirmed that the generated minerals are high-purity schwertmannite. Experimental and theoretical analyses revealed that in the presence of cathodic alkalinity, Fe(III) undergoes further hydrolysis to form [(H₂O)3Fe(OH)2(SO4)]− species, which are thermodynamically capable of spontaneous polymerization and mineralization. Furthermore, the photoreduction of [(H₂O)4Fe(SO4)2]− within the PEC system, followed by subsequent oxidation, plays a crucial role in facilitating Fe(III) mineralization. The PEC system also effectively transformed As(III) to As(V) and Cr(VI) to Cr(III) in AMD, promoting their immobilization in the resultant schwertmannite.
{"title":"Overcoming Fe(III) precipitation barrier in acid mine drainage via a visible light-assisted photo-electrochemical system","authors":"Yang Wang , Ziyuan Huang , Zhang Yan , Zhenchao Lei , Huanxin Ma , Chunhua Feng","doi":"10.1016/j.watres.2025.123193","DOIUrl":"10.1016/j.watres.2025.123193","url":null,"abstract":"<div><div>Acid mine drainage (AMD) is characterized by high concentrations of Fe(II) and Fe(III), which can be harnessed for the in-situ formation of schwertmannite, enabling the efficient immobilization of toxic heavy metals. However, existing biological and chemical methods for schwertmannite synthesis face significant challenges, including low Fe(II) oxidation rates and particularly limited Fe(III) precipitation efficiency in acidic environments. In this study, we develop a visible light-assisted photo-electrochemical (PEC) system that effectively overcomes these barriers. By leveraging anodically evolved O<sub>2</sub> and cathodically generated OH<sup>−</sup>, we achieved facile Fe(II) oxidation at pH 3.0, and an impressive Fe(III) precipitation efficiency of 82.8 %, significantly exceeding the < 30 % efficiency reported by other methods. Mössbauer spectroscopy and X-ray diffraction confirmed that the generated minerals are high-purity schwertmannite. Experimental and theoretical analyses revealed that in the presence of cathodic alkalinity, Fe(III) undergoes further hydrolysis to form [(H₂O)<sub>3</sub>Fe(OH)<sub>2</sub>(SO<sub>4</sub>)]<sup>−</sup> species, which are thermodynamically capable of spontaneous polymerization and mineralization. Furthermore, the photoreduction of [(H₂O)<sub>4</sub>Fe(SO<sub>4</sub>)<sub>2</sub>]<sup>−</sup> within the PEC system, followed by subsequent oxidation, plays a crucial role in facilitating Fe(III) mineralization. The PEC system also effectively transformed As(III) to As(V) and Cr(VI) to Cr(III) in AMD, promoting their immobilization in the resultant schwertmannite.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123193"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-27DOI: 10.1016/j.watres.2025.123209
Qingfei Chen , Heng Yang , Rongyang Cui , Wanli Hu , Chi Wang , Anqiang Chen , Dan Zhang
The accumulation of phosphorus (P) in soil profiles of intensive cropland and the losses caused by runoff and leaching have been widely concerned. However, the loss of soil P due to shallow groundwater table (SGT) fluctuations driven by seasonal changes is often neglected, and the migration and transformation mechanisms of soil P are still unclear. On the basis of the long-term monitoring of cropland soil P accumulation and SGT fluctuations around Erhai Lake, the characteristics of soil P loss driven by SGT fluctuations and the corresponding mechanisms were investigated through a 260-day microcosm experiment. The results revealed that the fluctuations in SGT significantly changed the content and form of P in the soil profile. The soil P loss mainly occurred in dissolved form, mainly involving inorganic P, accounting for 75 %. Compared with those under continuous saturated conditions, soil total P (TP) release during SGT fluctuations significantly increased by 9.5 %, and soil TP storage was reduced by 2 %. SGT fluctuations increased the complexity of microbial networks in the soil profile, stimulated the expression of functional genes for soil P cycling, and promoted soil organic P mineralization. The SGT fluctuations caused an increase in the soil TP loss from cropland to 88.5 kg/ha, which was 70 and 25 times greater than that via leaching and runoff, respectively. These results indicated that SGT fluctuations accelerated the P loss from soil profile of cropland. Therefore, some measures should be comprehensively applied to prevent its loss, such as reducing external P input, improving surface soil P storage capacity and soil P utilization efficiency, reducing surface P leaching into deep soil, and reducing P accumulation in deep soil profiles.
{"title":"Shallow groundwater table fluctuations: A driving force for accelerating the migration and transformation of phosphorus in cropland soil","authors":"Qingfei Chen , Heng Yang , Rongyang Cui , Wanli Hu , Chi Wang , Anqiang Chen , Dan Zhang","doi":"10.1016/j.watres.2025.123209","DOIUrl":"10.1016/j.watres.2025.123209","url":null,"abstract":"<div><div>The accumulation of phosphorus (P) in soil profiles of intensive cropland and the losses caused by runoff and leaching have been widely concerned. However, the loss of soil P due to shallow groundwater table (SGT) fluctuations driven by seasonal changes is often neglected, and the migration and transformation mechanisms of soil P are still unclear. On the basis of the long-term monitoring of cropland soil P accumulation and SGT fluctuations around Erhai Lake, the characteristics of soil P loss driven by SGT fluctuations and the corresponding mechanisms were investigated through a 260-day microcosm experiment. The results revealed that the fluctuations in SGT significantly changed the content and form of P in the soil profile. The soil P loss mainly occurred in dissolved form, mainly involving inorganic P, accounting for 75 %. Compared with those under continuous saturated conditions, soil total P (TP) release during SGT fluctuations significantly increased by 9.5 %, and soil TP storage was reduced by 2 %. SGT fluctuations increased the complexity of microbial networks in the soil profile, stimulated the expression of functional genes for soil P cycling, and promoted soil organic P mineralization. The SGT fluctuations caused an increase in the soil TP loss from cropland to 88.5 kg/ha, which was 70 and 25 times greater than that via leaching and runoff, respectively. These results indicated that SGT fluctuations accelerated the P loss from soil profile of cropland. Therefore, some measures should be comprehensively applied to prevent its loss, such as reducing external P input, improving surface soil P storage capacity and soil P utilization efficiency, reducing surface P leaching into deep soil, and reducing P accumulation in deep soil profiles.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123209"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-27DOI: 10.1016/j.watres.2025.123177
Daoxi Zhang , Zhiyong Zhang , Jan-Peter Muller , Liming Zhu , Sanfeng Zhang , Ji Wan , Fang Shi , Xi Zou , Yulong Shi
The upstream cascade reservoirs and the implementation of soil and water conservation practices have effectively mitigated sediment inflow to the Three Gorges Reservoir (TGR) since it was fully operational in 2010. However, total deposited sediments and algal blooms in its tributaries have increased during the post-TGR period. To investigate the spatial distribution characteristics of deposited fractional phosphorus in sediments and its influencing factors, column sediment and overlying water datasets collected from field campaigns were analysed using the multivariate statistical approaches by Partial Triadic Analysis (PTA) and Redundancy Analysis (RDA). The results revealed that fractional phosphorus within the top 20 cm of the column sediment exhibited a distinct vertical structure, and the mean contents of total phosphorus (TP), inorganic phosphorus (Inorg-P) and calcium-bound phosphorus (Ca-P) contents were significantly higher than those measured in the deeper layer. Additionally, fractional phosphorus in the mainstream and estuary sections showed longitudinal distribution patterns. Inorg-P and Ca-P were prevalent in the upstream reaches, while the organic phosphorus (Org-P) and iron-aluminium-bound phosphorus (Fe/Al-P) were enriched in the lower mainstream and estuary regions. Sediment TP reached the highest level in the middle river reach. Multivariate regression via the RDA and variance partitioning indicated that environmental factors of the overlying water were significantly correlated with surface sediment phosphorus levels (, ). Physicochemical variables, particularly water temperature, exerted a stronger influence on the spatial allocation of sediment phosphorus fractions compared to water phosphorus content during the flood season. These findings highlight the need to address nutrients introduced from the mainstream to tributaries via backwater intrusion before implementing flood operation approaches for algal bloom mitigation. Furthermore, biomanipulation-based schemes may represent a promising strategy for improving water quality in TGR tributaries.
{"title":"Water temperature exhibits an overwhelming effect on the spatial allocation of sediment phosphorus fractions in the permanent backwater area of the Three Gorges Reservoir, China","authors":"Daoxi Zhang , Zhiyong Zhang , Jan-Peter Muller , Liming Zhu , Sanfeng Zhang , Ji Wan , Fang Shi , Xi Zou , Yulong Shi","doi":"10.1016/j.watres.2025.123177","DOIUrl":"10.1016/j.watres.2025.123177","url":null,"abstract":"<div><div>The upstream cascade reservoirs and the implementation of soil and water conservation practices have effectively mitigated sediment inflow to the Three Gorges Reservoir (TGR) since it was fully operational in 2010. However, total deposited sediments and algal blooms in its tributaries have increased during the post-TGR period. To investigate the spatial distribution characteristics of deposited fractional phosphorus in sediments and its influencing factors, column sediment and overlying water datasets collected from field campaigns were analysed using the multivariate statistical approaches by Partial Triadic Analysis (PTA) and Redundancy Analysis (RDA). The results revealed that fractional phosphorus within the top 20 cm of the column sediment exhibited a distinct vertical structure, and the mean contents of total phosphorus (TP), inorganic phosphorus (Inorg-P) and calcium-bound phosphorus (Ca-P) contents were significantly higher than those measured in the deeper layer. Additionally, fractional phosphorus in the mainstream and estuary sections showed longitudinal distribution patterns. Inorg-P and Ca-P were prevalent in the upstream reaches, while the organic phosphorus (Org-P) and iron-aluminium-bound phosphorus (Fe/Al-P) were enriched in the lower mainstream and estuary regions. Sediment TP reached the highest level in the middle river reach. Multivariate regression via the RDA and variance partitioning indicated that environmental factors of the overlying water were significantly correlated with surface sediment phosphorus levels (<span><math><mrow><msubsup><mrow><mi>R</mi></mrow><mrow><mi>a</mi><mi>d</mi><mi>j</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>=</mo><mn>0</mn><mo>.</mo><mn>33</mn></mrow></math></span>, <span><math><mrow><mi>p</mi><mo><</mo><mn>0</mn><mo>.</mo><mn>05</mn></mrow></math></span>). Physicochemical variables, particularly water temperature, exerted a stronger influence on the spatial allocation of sediment phosphorus fractions compared to water phosphorus content during the flood season. These findings highlight the need to address nutrients introduced from the mainstream to tributaries via backwater intrusion before implementing flood operation approaches for algal bloom mitigation. Furthermore, biomanipulation-based schemes may represent a promising strategy for improving water quality in TGR tributaries.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"276 ","pages":"Article 123177"},"PeriodicalIF":11.4,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-26DOI: 10.1016/j.watres.2025.123210
Nuoxiao Yan , Zhiqiang Qiu , Chenxue Zhang , Yao Yan , Dong Liu
River organic pollution exhibits pronounced spatiotemporal dynamics in response to environmental changes. However, the traditional method of tracking chemical oxygen demand (COD) and/or other organic pollution indicators at fixed locations over expansive regions is labor-intensive, time-consuming, and inadequate for achieving full spatial coverage. To address this limitation, here we developed a Random Forest algorithm using Landsat satellite data in conjunction with sub-daily (every 4 h) COD data at 1,997 sites across China. The proposed model achieved high accuracy, with a root mean square error of 0.52 mg/L and a mean absolute percent difference of 13.01 %. Additionally, the model was robust across clear, algae-laden, turbid, and black-smelling waters. Then, the algorithm was applied to investigate the spatiotemporal variations of COD concentration in Chinese rivers during 1984–2023. Across China, high river COD concentrations were observed in the eastern Songliao (3.56 ± 1.11 mg/L), Haihe (3.00 ± 0.89 mg/L), and Huaihe (3.57 ± 0.67 mg/L) basins. Anthropogenic activities could explain 79.39 % of the spatial variability in COD concentrations, and the cropland distribution had a significant impact. During 1984–2023, 73.58 % of China's rivers exhibited significant changes in COD concentrations (p < 0.05). With respect to the 800 mm isoprecipitation line, 56.62 % of the southeastern rivers showed decreasing trends; in contrast, 84.25 % of the northwestern rivers displayed increasing trends in COD concentrations. The temporal variations in COD concentrations were driven by the combined effects of factors including rainfall, vegetation coverage, and human activities; their relative contributions were 0.02 – 42.45 %, 0.07 – 68.76 %, and 0.06 – 90.31 % for COD changes in different provinces. This study underscores the feasibilities of using long-term Landsat data to efficiently and dynamically monitor organic pollution in rivers on a large scale, providing crucial implications for spatiotemporal monitoring of other water quality indicators.
{"title":"Landsat monitoring reveals the history of river organic pollution across China during 1984–2023","authors":"Nuoxiao Yan , Zhiqiang Qiu , Chenxue Zhang , Yao Yan , Dong Liu","doi":"10.1016/j.watres.2025.123210","DOIUrl":"10.1016/j.watres.2025.123210","url":null,"abstract":"<div><div>River organic pollution exhibits pronounced spatiotemporal dynamics in response to environmental changes. However, the traditional method of tracking chemical oxygen demand (COD) and/or other organic pollution indicators at fixed locations over expansive regions is labor-intensive, time-consuming, and inadequate for achieving full spatial coverage. To address this limitation, here we developed a Random Forest algorithm using Landsat satellite data in conjunction with sub-daily (every 4 h) COD data at 1,997 sites across China. The proposed model achieved high accuracy, with a root mean square error of 0.52 mg/L and a mean absolute percent difference of 13.01 %. Additionally, the model was robust across clear, algae-laden, turbid, and black-smelling waters. Then, the algorithm was applied to investigate the spatiotemporal variations of COD concentration in Chinese rivers during 1984–2023. Across China, high river COD concentrations were observed in the eastern Songliao (3.56 ± 1.11 mg/L), Haihe (3.00 ± 0.89 mg/L), and Huaihe (3.57 ± 0.67 mg/L) basins. Anthropogenic activities could explain 79.39 % of the spatial variability in COD concentrations, and the cropland distribution had a significant impact. During 1984–2023, 73.58 % of China's rivers exhibited significant changes in COD concentrations (<em>p</em> < 0.05). With respect to the 800 mm isoprecipitation line, 56.62 % of the southeastern rivers showed decreasing trends; in contrast, 84.25 % of the northwestern rivers displayed increasing trends in COD concentrations. The temporal variations in COD concentrations were driven by the combined effects of factors including rainfall, vegetation coverage, and human activities; their relative contributions were 0.02 – 42.45 %, 0.07 – 68.76 %, and 0.06 – 90.31 % for COD changes in different provinces. This study underscores the feasibilities of using long-term Landsat data to efficiently and dynamically monitor organic pollution in rivers on a large scale, providing crucial implications for spatiotemporal monitoring of other water quality indicators.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123210"},"PeriodicalIF":11.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-26DOI: 10.1016/j.watres.2025.123171
Andrew Murray , Alexander Hall , Diego Riveros-Iregui
In the United States, people obtain water for household use from one of two sources. Public water systems, which are subject to rules and regulations under the Safe Drinking Water Act, or private sources such as domestic wells, which are not subject to federal regulation and are generally the responsibility of the homeowner or occupant. Public water systems are required to treat their drinking water and conduct regular testing to ensure the delivery of safe water to consumers. From a public health perspective, it is essential to know who is drinking what water to determine risk and impacts from water-borne disease and contamination. We present a new machine-learning approach to estimating water supply source (public or private) at the census block level for the year 2020. While previous studies have largely focused on spatially delineating either public or private water supply, our method incorporates data from both universes, resulting in more accurate modeling results. The utilization of machine learning and additional explanatory data that have not been considered in prior studies results in the most accurate and up-to-date estimate of the count and location of users supplying household water from either a private source or a public water supply. We estimate that 14.1 % of US housing units are supplied by private wells and 84.9 % of housing units are served by a public water system as of 2020.
在美国，人们从两种水源之一获取家庭用水。一种是公共供水系统，受《安全饮用水法》（Safe Drinking Water Act）的规则和法规约束；另一种是私人水源，如家用水井，不受联邦法规约束，通常由房主或住户负责。公共供水系统必须对饮用水进行处理，并定期进行检测，以确保向消费者提供安全的水。从公共卫生的角度来看，必须了解谁在饮用什么水，以确定水传播疾病和污染的风险和影响。我们提出了一种新的机器学习方法，用于估算 2020 年人口普查区块层面的供水来源（公共或私人）。以往的研究主要集中在公共或私人供水的空间划分上，而我们的方法结合了这两个领域的数据，从而得出了更准确的建模结果。利用机器学习和额外的解释性数据（这些数据在之前的研究中没有考虑过），我们可以对从私人水源或公共水源供应家庭用水的用户数量和位置做出最准确、最新的估计。我们估计，到 2020 年，14.1% 的美国住房单元由私人水井供水，84.9% 的住房单元由公共供水系统供水。
{"title":"A machine learning approach to estimate domestic use of public and private water sources in the United States","authors":"Andrew Murray , Alexander Hall , Diego Riveros-Iregui","doi":"10.1016/j.watres.2025.123171","DOIUrl":"10.1016/j.watres.2025.123171","url":null,"abstract":"<div><div>In the United States, people obtain water for household use from one of two sources. Public water systems, which are subject to rules and regulations under the Safe Drinking Water Act, or private sources such as domestic wells, which are not subject to federal regulation and are generally the responsibility of the homeowner or occupant. Public water systems are required to treat their drinking water and conduct regular testing to ensure the delivery of safe water to consumers. From a public health perspective, it is essential to know who is drinking what water to determine risk and impacts from water-borne disease and contamination. We present a new machine-learning approach to estimating water supply source (public or private) at the census block level for the year 2020. While previous studies have largely focused on spatially delineating either public or private water supply, our method incorporates data from both universes, resulting in more accurate modeling results. The utilization of machine learning and additional explanatory data that have not been considered in prior studies results in the most accurate and up-to-date estimate of the count and location of users supplying household water from either a private source or a public water supply. We estimate that 14.1 % of US housing units are supplied by private wells and 84.9 % of housing units are served by a public water system as of 2020.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"276 ","pages":"Article 123171"},"PeriodicalIF":11.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-01-26DOI: 10.1016/j.watres.2025.123203
Mengkai Li , Yihao Zheng , Yanyan Huang , Jiaying Li , Zhe Sun , Ernest R. Blatchley III , Zhimin Qiang
Quartz sleeve scaling significantly affects the efficacy of ultraviolet (UV) processes for water treatment. Investigating the scaling process and developing prediction methods are important for selecting and optimizing scaling control measures. However, these have been limited by the lack of an appropriate experimental system. Therefore, this study investigated the kinetics, mechanisms, and prediction methods of calcium scaling (a predominant scale compound encountered in drinking water treatment) on quartz sleeves. An on-line experimental system for sleeve scale UV transmittance (UVTSS) was developed based on previously developed micro-fluorescent silica detectors. The scaling process was accelerated by increases in [Ca2+] (100–400 mg L–1), alkalinity (100–400 mg L–1), and pH (6.5–8.5). Furthermore, water temperature (20.0–30.0 °C), sleeve temperature (24.9–31.7 °C), and flow velocity (2.5–10.0 cm s–1) exhibited diverse effects on calcium scaling. By delving into scaling mechanisms such as mass transfer, surface crystallization, and scale stripping processes, we proposed a prediction model. The extinction coefficient and stripping rate of calcium scale were estimated to be 0.80 μm–1 and 0.155 h–1, respectively. Model predictions were validated through both laboratory and field tests. This study provides important methods for ensuring sufficient dose delivery by a UV reactor, enhancing energy efficiency, and improving reliability in UV processes for water treatment.
{"title":"Calcium scaling on the quartz sleeve of ultraviolet reactor: On-line measurement and model prediction","authors":"Mengkai Li , Yihao Zheng , Yanyan Huang , Jiaying Li , Zhe Sun , Ernest R. Blatchley III , Zhimin Qiang","doi":"10.1016/j.watres.2025.123203","DOIUrl":"10.1016/j.watres.2025.123203","url":null,"abstract":"<div><div>Quartz sleeve scaling significantly affects the efficacy of ultraviolet (UV) processes for water treatment. Investigating the scaling process and developing prediction methods are important for selecting and optimizing scaling control measures. However, these have been limited by the lack of an appropriate experimental system. Therefore, this study investigated the kinetics, mechanisms, and prediction methods of calcium scaling (a predominant scale compound encountered in drinking water treatment) on quartz sleeves. An on-line experimental system for sleeve scale UV transmittance (UVT<sub>SS</sub>) was developed based on previously developed micro-fluorescent silica detectors. The scaling process was accelerated by increases in [Ca<sup>2+</sup>] (100–400 mg L<sup>–1</sup>), alkalinity (100–400 mg L<sup>–1</sup>), and pH (6.5–8.5). Furthermore, water temperature (20.0–30.0 °C), sleeve temperature (24.9–31.7 °C), and flow velocity (2.5–10.0 cm s<sup>–1</sup>) exhibited diverse effects on calcium scaling. By delving into scaling mechanisms such as mass transfer, surface crystallization, and scale stripping processes, we proposed a prediction model. The extinction coefficient and stripping rate of calcium scale were estimated to be 0.80 μm<sup>–1</sup> and 0.155 h<sup>–1</sup>, respectively. Model predictions were validated through both laboratory and field tests. This study provides important methods for ensuring sufficient dose delivery by a UV reactor, enhancing energy efficiency, and improving reliability in UV processes for water treatment.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"275 ","pages":"Article 123203"},"PeriodicalIF":11.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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