Pub Date : 2024-11-19DOI: 10.1016/j.jconhyd.2024.104468
Zhixin Chen, Yan Tian, Liming Hu
Propylene glycol (PG)-mixed steam enhanced extraction is a promising remediation technique for removing semi-volatile organic compounds (SVOCs) from the unsaturated zone. However, the mechanisms of heat and moisture transfer during PG-mixed steam injection remain unclear. In this study, a 2D experimental system was developed to enable non-invasive monitoring of the spatio-temporal distribution of temperature and degree of saturation during steam injection into porous media. Experiments were conducted to observe the migration of PG-mixed steam in horizontal and vertical planes across three varying particle sizes, while pure superheated steam injection experiments serving as a comparison. Temperature field results show that the addition of PG decreases the zone of influence during steam migration, while significantly enhancing the emergence of the superheated steam zone. The influence of particle size on the area variance of the saturated steam zone is greater than that of the superheated steam zone. The downward migration of the superheated steam front due to density different between PG vapor and air is impeded with decreasing permeability. Furthermore, saturation field results reveal that the condensed liquid within the superheated zone is a PG solution. The downward migration of condensates with high PG concentration might increase the potential risk of beneath groundwater pollution, highlighting the significance of understanding PG migration during PG-mixed steam injection.
{"title":"Experimental investigation on heat and moisture transfer of propylene glycol-mixed steam in porous media","authors":"Zhixin Chen, Yan Tian, Liming Hu","doi":"10.1016/j.jconhyd.2024.104468","DOIUrl":"10.1016/j.jconhyd.2024.104468","url":null,"abstract":"<div><div>Propylene glycol (PG)-mixed steam enhanced extraction is a promising remediation technique for removing semi-volatile organic compounds (SVOCs) from the unsaturated zone. However, the mechanisms of heat and moisture transfer during PG-mixed steam injection remain unclear. In this study, a 2D experimental system was developed to enable non-invasive monitoring of the spatio-temporal distribution of temperature and degree of saturation during steam injection into porous media. Experiments were conducted to observe the migration of PG-mixed steam in horizontal and vertical planes across three varying particle sizes, while pure superheated steam injection experiments serving as a comparison. Temperature field results show that the addition of PG decreases the zone of influence during steam migration, while significantly enhancing the emergence of the superheated steam zone. The influence of particle size on the area variance of the saturated steam zone is greater than that of the superheated steam zone. The downward migration of the superheated steam front due to density different between PG vapor and air is impeded with decreasing permeability. Furthermore, saturation field results reveal that the condensed liquid within the superheated zone is a PG solution. The downward migration of condensates with high PG concentration might increase the potential risk of beneath groundwater pollution, highlighting the significance of understanding PG migration during PG-mixed steam injection.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104468"},"PeriodicalIF":3.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706291","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}
Under persistent hypoxic conditions in the bottom layer of a lake, phosphorus (P) can be released from benthic sediments, significantly impacting the lake ecosystem. Hypoxia reduces iron ions, leading to P release through biogeochemical reactions associated with organic matter degradation, which in turn depletes dissolved oxygen (DO) in the sediment. The application of bubble technology is beneficial, as microbubbles (MBs) effectively remove P and enhance DO levels in both the overlying water and sediment surface. To identify the optimal bubble size for application, we conducted a series of flotation experiments and P fractionation studies using MBs and nanobubbles (NBs). Results indicate that NBs achieved a flotation efficiency of 12 %, MBs reached 44 %, and the combined use of NBs and MBs attained the highest flotation efficiency at 62 %, confirming that a combination of bubble sizes can enhance flotation efficiency. Furthermore, the introduction of air bubbles to mitigate hypoxia in the overlying water increased DO concentrations from 1 to 5 mg/L, followed by a gradual decline. P release in the bubble-injected groups was up to three times lower than in the control group. Water quality profiling of P distribution in sediments revealed a significant increase of approximately 10 % in iron-bound P under aerobic conditions, highlighting its critical role in regulating P release. Our findings suggest that utilizing a combination of bubble sizes, including NBs, enhances P removal efficiency and improves the anaerobic conditions of the lake's bottom layer, thereby further reducing P release from sediments.
在湖泊底层持续缺氧的条件下,磷(P)会从底栖沉积物中释放出来,对湖泊生态系统产生重大影响。缺氧会减少铁离子,导致磷通过与有机物降解相关的生物地球化学反应释放出来,进而消耗沉积物中的溶解氧(DO)。气泡技术的应用是有益的,因为微气泡(MBs)能有效去除 P 并提高上覆水体和沉积物表面的溶解氧水平。为了确定应用的最佳气泡尺寸,我们使用微气泡和纳米气泡(NBs)进行了一系列浮选实验和 P 分馏研究。结果表明,NBs 的浮选效率为 12%,MBs 为 44%,而结合使用 NBs 和 MBs 的浮选效率最高,达到 62%,这证实了气泡大小的组合可提高浮选效率。此外,通过引入气泡来缓解上层水的缺氧状况,溶解氧浓度从 1 毫克/升上升到 5 毫克/升,随后逐渐下降。气泡注入组的 P 释放量是对照组的三倍。沉积物中 P 分布的水质剖面图显示,在有氧条件下,铁结合的 P 显著增加了约 10%,突出了其在调节 P 释放中的关键作用。我们的研究结果表明,利用包括 NBs 在内的多种气泡尺寸组合可提高对 P 的去除效率,改善湖泊底层的厌氧条件,从而进一步减少沉积物中 P 的释放。
{"title":"Experimental application of micro/nano bubbles to control P release and separate P particles from benthic lake sediment","authors":"Yong-Ho Choi , Yong-Hoon Jeong , Hong-Hue Thi Nguyen , Dong-Heui Kwak","doi":"10.1016/j.jconhyd.2024.104466","DOIUrl":"10.1016/j.jconhyd.2024.104466","url":null,"abstract":"<div><div>Under persistent hypoxic conditions in the bottom layer of a lake, phosphorus (P) can be released from benthic sediments, significantly impacting the lake ecosystem. Hypoxia reduces iron ions, leading to P release through biogeochemical reactions associated with organic matter degradation, which in turn depletes dissolved oxygen (DO) in the sediment. The application of bubble technology is beneficial, as microbubbles (MBs) effectively remove P and enhance DO levels in both the overlying water and sediment surface. To identify the optimal bubble size for application, we conducted a series of flotation experiments and P fractionation studies using MBs and nanobubbles (NBs). Results indicate that NBs achieved a flotation efficiency of 12 %, MBs reached 44 %, and the combined use of NBs and MBs attained the highest flotation efficiency at 62 %, confirming that a combination of bubble sizes can enhance flotation efficiency. Furthermore, the introduction of air bubbles to mitigate hypoxia in the overlying water increased DO concentrations from 1 to 5 mg/L, followed by a gradual decline. P release in the bubble-injected groups was up to three times lower than in the control group. Water quality profiling of P distribution in sediments revealed a significant increase of approximately 10 % in iron-bound P under aerobic conditions, highlighting its critical role in regulating P release. Our findings suggest that utilizing a combination of bubble sizes, including NBs, enhances P removal efficiency and improves the anaerobic conditions of the lake's bottom layer, thereby further reducing P release from sediments.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104466"},"PeriodicalIF":3.5,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142693027","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}
Pub Date : 2024-11-12DOI: 10.1016/j.jconhyd.2024.104456
Rozita Soltani Tehrani, Xiaomei Yang, Jos van Dam
Microplastic pollution has become a growing concern in terrestrial ecosystems, with significant implications for environmental and human health. Understanding the fate and transport of microplastics in soil environment is crucial for effective mitigation strategies. This study investigates the dynamics of microplastic (Low-density polyethylene (LDPE), polybutylene adipate terephthalate (PBAT), and starch-based biodegradable plastic) transport in unsaturated soils under varying rainfall intensities and soil types, aiming to elucidate the factors influencing their behavior. Effluent samples were analyzed to measure microplastic transport, with microplastic balance analysis ensuring experimental accuracy. The setup replicated real-world flow conditions, providing insights into microplastic transport in unsaturated porous media. Microplastic balance analysis revealed high recovery factors (between 64 % and 104 %), indicating the reliability of the experimental approach. Microplastic transport varied significantly between sandy loam and loamy sand soils, with loamy sand soils exhibiting higher wash-off rates due to their unique properties. LDPE microplastics showed a higher tendency to detach from soil columns compared to PBAT and starch-based particles. Higher rainfall intensity in loamy sand soil columns resulted in an increased washout of LDPE, PBAT, and starch-based particles by 92 %, 144 %, and 85 %, respectively, compared to low rainfall intensity. In sandy loam soil, increased rainfall intensity resulted in a significantly higher washout of LDPE, PBAT, and starch-based particles with percentages of 93 %, 69 %, and 45 %, respectively. This underscores the important role of water flow in mobilizing microplastics within the soil matrix.
{"title":"Rainfall-induced microplastic fate and transport in unsaturated Dutch soils","authors":"Rozita Soltani Tehrani, Xiaomei Yang, Jos van Dam","doi":"10.1016/j.jconhyd.2024.104456","DOIUrl":"10.1016/j.jconhyd.2024.104456","url":null,"abstract":"<div><div>Microplastic pollution has become a growing concern in terrestrial ecosystems, with significant implications for environmental and human health. Understanding the fate and transport of microplastics in soil environment is crucial for effective mitigation strategies. This study investigates the dynamics of microplastic (Low-density polyethylene (LDPE), polybutylene adipate terephthalate (PBAT), and starch-based biodegradable plastic) transport in unsaturated soils under varying rainfall intensities and soil types, aiming to elucidate the factors influencing their behavior. Effluent samples were analyzed to measure microplastic transport, with microplastic balance analysis ensuring experimental accuracy. The setup replicated real-world flow conditions, providing insights into microplastic transport in unsaturated porous media. Microplastic balance analysis revealed high recovery factors (between 64 % and 104 %), indicating the reliability of the experimental approach. Microplastic transport varied significantly between sandy loam and loamy sand soils, with loamy sand soils exhibiting higher wash-off rates due to their unique properties. LDPE microplastics showed a higher tendency to detach from soil columns compared to PBAT and starch-based particles. Higher rainfall intensity in loamy sand soil columns resulted in an increased washout of LDPE, PBAT, and starch-based particles by 92 %, 144 %, and 85 %, respectively, compared to low rainfall intensity. In sandy loam soil, increased rainfall intensity resulted in a significantly higher washout of LDPE, PBAT, and starch-based particles with percentages of 93 %, 69 %, and 45 %, respectively. This underscores the important role of water flow in mobilizing microplastics within the soil matrix.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104456"},"PeriodicalIF":3.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142643982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-11-10DOI: 10.1016/j.jconhyd.2024.104458
Mengyao Jing , Jianping Zhang , Guijuan Li , Dan Zhang , Fengjia Liu , Shengke Yang
The phenomenon of antibiotic pollution has emerged as a significant global environmental concern. However, there is a lack of technical research on the effective removal of antibiotics based on the characteristics of the groundwater environment. This paper used micro-nano bubbles (MNBs) enhanced immobilized Chlorella technology to remove ofloxacin (OFLX) from groundwater. The study discussed the impact of initial antibiotic concentration (5–30 mg/mL), algae concentration (0.25–4 bead/mL), aeration time (5–30 min), and coexisting ions on the antibiotic removal rate and analyzed the removal mechanism by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The results showed that MNBs increased Chlorella vulgaris biomass by 2.48 times and significantly improved OFLX removal efficiency. The removal rate of OFLX exhibited a significant positive correlation with the algal concentration and coexisting ions and a significant negative correlation with the aeration time and the initial concentration of antibiotics. Enhanced immobilization of Chlorella vulgaris by MNBs for OFLX removal may involve -NH, -OH, -C=O, -CH2, and -C-O-C groups. Degradation (including biodegradation and non-biodegradation) is the primary mechanism of antibiotic removal. Overall, intensive immobilization of Chlorella by MNBs promises to be a technically feasible method for removing antibiotics from groundwater.
{"title":"Micro-nano bubbles enhanced immobilized Chlorella vulgaris to remove ofloxacin from groundwater","authors":"Mengyao Jing , Jianping Zhang , Guijuan Li , Dan Zhang , Fengjia Liu , Shengke Yang","doi":"10.1016/j.jconhyd.2024.104458","DOIUrl":"10.1016/j.jconhyd.2024.104458","url":null,"abstract":"<div><div>The phenomenon of antibiotic pollution has emerged as a significant global environmental concern. However, there is a lack of technical research on the effective removal of antibiotics based on the characteristics of the groundwater environment. This paper used micro-nano bubbles (MNBs) enhanced immobilized Chlorella technology to remove ofloxacin (OFLX) from groundwater. The study discussed the impact of initial antibiotic concentration (5–30 mg/mL), algae concentration (0.25–4 bead/mL), aeration time (5–30 min), and coexisting ions on the antibiotic removal rate and analyzed the removal mechanism by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The results showed that MNBs increased <em>Chlorella vulgaris</em> biomass by 2.48 times and significantly improved OFLX removal efficiency. The removal rate of OFLX exhibited a significant positive correlation with the algal concentration and coexisting ions and a significant negative correlation with the aeration time and the initial concentration of antibiotics. Enhanced immobilization of <em>Chlorella vulgaris</em> by MNBs for OFLX removal may involve -NH, -OH, -C=O, -CH<sub>2</sub>, and -C-O-C groups. Degradation (including biodegradation and non-biodegradation) is the primary mechanism of antibiotic removal. Overall, intensive immobilization of Chlorella by MNBs promises to be a technically feasible method for removing antibiotics from groundwater.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104458"},"PeriodicalIF":3.5,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142662825","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}
Pub Date : 2024-11-04DOI: 10.1016/j.jconhyd.2024.104454
Swagatam Chakraborty , Fuad Alqrinawi , Jan Willem Foppen , Jack Schijven
Identifying and determining hydraulic parameters of physically heterogeneous aquifers is pivotal for flow field analysis, contaminant migration and risk assessment. In this research, we applied a novel uniquely sequenced DNA tagged superparamagnetic silica microparticles (SiDNAmag) to quantify hydraulic parameters and associated uncertainties of a heterogeneous sand tank. In the sand tank with lens shaped heterogeneity, we conducted three sets of multi – point injection experiments in unconsolidated (1) homogeneous (zone 0), (2) heterogeneous with a no-conductivity-zone (zone 1), and (3) heterogeneous with a high-conductive-zone (zone 2). From the breakthrough curves (BTC), we estimated the parameters distributions of hydraulic conductivity (k), effective porosity (ne), longitudinal dispersivity (αL), transverse vertical (αTV), and transverse horizontal dispersivities (αTH) applying Monte Carlo simulation approach for BTC fitting. The estimated parameters and associated uncertainties for each of the heterogeneous sections were further statistically compared (distribution non-specific Mann Whitney U test) these parameter distributions with parameter distributions estimated from the conservative salt tracer. While the time of arrival and time to peak concentration of SiDNAmag and salt in effluent were comparable, peak concentration of SiDNAmag was 1–3 log reduced as compared to the salt tracer due to first order kinetic attachment. Nonetheless, the parameters and associated uncertainty distributions (5 %–95 %) of K, ne, αL, αTV, and αTH, determined from SiDNAmag BTCs were statistically equivalent to the salt tracer in all three experiment systems. Through our experimental and modelling approach, our work demonstrated that in a coarse to very coarse grain sand medium, with lens shaped heterogeneity, the uniquely sequenced SiDNAmag were a promising tool to identify heterogeneity and determine hydraulic parameters and associated uncertainty distributions.
{"title":"Quantifying aquifer heterogeneity using superparamagnetic DNA particles","authors":"Swagatam Chakraborty , Fuad Alqrinawi , Jan Willem Foppen , Jack Schijven","doi":"10.1016/j.jconhyd.2024.104454","DOIUrl":"10.1016/j.jconhyd.2024.104454","url":null,"abstract":"<div><div>Identifying and determining hydraulic parameters of physically heterogeneous aquifers is pivotal for flow field analysis, contaminant migration and risk assessment. In this research, we applied a novel uniquely sequenced DNA tagged superparamagnetic silica microparticles (SiDNAmag) to quantify hydraulic parameters and associated uncertainties of a heterogeneous sand tank. In the sand tank with lens shaped heterogeneity, we conducted three sets of multi – point injection experiments in unconsolidated (1) homogeneous (zone 0), (2) heterogeneous with a no-conductivity-zone (zone 1), and (3) heterogeneous with a high-conductive-zone (zone 2). From the breakthrough curves (BTC), we estimated the parameters distributions of hydraulic conductivity (k), effective porosity (n<sub>e</sub>), longitudinal dispersivity (α<sub>L</sub>), transverse vertical (α<sub>TV</sub>), and transverse horizontal dispersivities (α<sub>TH</sub>) applying Monte Carlo simulation approach for BTC fitting. The estimated parameters and associated uncertainties for each of the heterogeneous sections were further statistically compared (distribution non-specific Mann Whitney <em>U</em> test) these parameter distributions with parameter distributions estimated from the conservative salt tracer. While the time of arrival and time to peak concentration of SiDNAmag and salt in effluent were comparable, peak concentration of SiDNAmag was 1–3 log reduced as compared to the salt tracer due to first order kinetic attachment. Nonetheless, the parameters and associated uncertainty distributions (5 %–95 %) of K, n<sub>e</sub>, α<sub>L</sub>, α<sub>TV</sub>, and α<sub>TH</sub>, determined from SiDNAmag BTCs were statistically equivalent to the salt tracer in all three experiment systems. Through our experimental and modelling approach, our work demonstrated that in a coarse to very coarse grain sand medium, with lens shaped heterogeneity, the uniquely sequenced SiDNAmag were a promising tool to identify heterogeneity and determine hydraulic parameters and associated uncertainty distributions.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104454"},"PeriodicalIF":3.5,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142687231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-11-03DOI: 10.1016/j.jconhyd.2024.104453
A. Bøllingtoft , P.L. Bjerg , V. Rønde , N. Tuxen , W. Nowak , M. Troldborg
Contaminant mass discharge (CMD) estimation involves combining multilevel concentration and flow measurements to quantify the contaminant mass passing through a control plane downgradient of a point source. However, geological heterogeneities and limited data introduce uncertainties that complicate CMD estimation and risk assessment. Although CMD is increasingly used in groundwater management, methods for quantifying and handling these uncertainties are still needed. This study develops and tests a CMD estimation method based on Bayesian geostatistics to quantify CMD uncertainties using data from a control plane perpendicular to the contaminant plume.
By combining geostatistical conditional simulations of the spatial concentration distribution with the flow, an ensemble of CMD realizations is generated, from which a cumulative distribution function is derived. A key element of this approach is the use of a macrodispersive transport model to simulate the spatial concentration trend. This ensures that the estimated concentration reflects the expected physical behavior of the contaminant plume while also allowing the integration of site-specific conceptual information.
The method is applicable to plumes with dissolved contaminants, such as chlorinated solvents, petroleum hydrocarbons, Per- and polyfluoroalkyl substances (PFAS) and pesticides. Site-specific conceptual understanding is used to inform the prior probability density functions of the structural model parameters and to define acceptable simulated concentration limits. We applied the method at three sites contaminated with chlorinated ethenes, demonstrating its robustness across varying information levels and data availability.
Our results shows that strong site-specific conceptual knowledge and high sampling density constrain the CMD uncertainty (CV = 21 %) and results in estimated model parameters and a spatial concentration distribution that agrees well with the conceptual model. For a site with less data and limited conceptual knowledge, CMD and concentration distribution estimates are still feasible, though with higher uncertainty (CV = 41 %). Extending the method to account for multiple source zones and complex plume migration improved parameter identification and reduced the 95 % CMD confidence interval by 11 % ([4950–8750] to [5090–8480] g yr−1), while also providing a spatial concentration distribution in better agreement with the plume conceptualization.
This study highlights the importance of integrating site-specific conceptual knowledge in CMD estimation, particularly for less-sampled sites. The method can furthermore assist in identifying remediation targets, evaluating remedial effectiveness, and optimizing sampling strategies.
{"title":"Quantification of contaminant mass discharge and uncertainties: Method and challenges in application at contaminated sites","authors":"A. Bøllingtoft , P.L. Bjerg , V. Rønde , N. Tuxen , W. Nowak , M. Troldborg","doi":"10.1016/j.jconhyd.2024.104453","DOIUrl":"10.1016/j.jconhyd.2024.104453","url":null,"abstract":"<div><div>Contaminant mass discharge (CMD) estimation involves combining multilevel concentration and flow measurements to quantify the contaminant mass passing through a control plane downgradient of a point source. However, geological heterogeneities and limited data introduce uncertainties that complicate CMD estimation and risk assessment. Although CMD is increasingly used in groundwater management, methods for quantifying and handling these uncertainties are still needed. This study develops and tests a CMD estimation method based on Bayesian geostatistics to quantify CMD uncertainties using data from a control plane perpendicular to the contaminant plume.</div><div>By combining geostatistical conditional simulations of the spatial concentration distribution with the flow, an ensemble of CMD realizations is generated, from which a cumulative distribution function is derived. A key element of this approach is the use of a macrodispersive transport model to simulate the spatial concentration trend. This ensures that the estimated concentration reflects the expected physical behavior of the contaminant plume while also allowing the integration of site-specific conceptual information.</div><div>The method is applicable to plumes with dissolved contaminants, such as chlorinated solvents, petroleum hydrocarbons, <em>Per</em>- and polyfluoroalkyl substances (PFAS) and pesticides. Site-specific conceptual understanding is used to inform the prior probability density functions of the structural model parameters and to define acceptable simulated concentration limits. We applied the method at three sites contaminated with chlorinated ethenes, demonstrating its robustness across varying information levels and data availability.</div><div>Our results shows that strong site-specific conceptual knowledge and high sampling density constrain the CMD uncertainty (CV = 21 %) and results in estimated model parameters and a spatial concentration distribution that agrees well with the conceptual model. For a site with less data and limited conceptual knowledge, CMD and concentration distribution estimates are still feasible, though with higher uncertainty (CV = 41 %). Extending the method to account for multiple source zones and complex plume migration improved parameter identification and reduced the 95 % CMD confidence interval by 11 % ([4950–8750] to [5090–8480] g yr<sup>−1</sup>), while also providing a spatial concentration distribution in better agreement with the plume conceptualization.</div><div>This study highlights the importance of integrating site-specific conceptual knowledge in CMD estimation, particularly for less-sampled sites. The method can furthermore assist in identifying remediation targets, evaluating remedial effectiveness, and optimizing sampling strategies.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"268 ","pages":"Article 104453"},"PeriodicalIF":3.5,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142621372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-11-01DOI: 10.1016/j.jconhyd.2024.104457
Riyanto Haribowo , Rizky Almarendra Wirawan Putra , Muchammad Ja'far Shiddik , Tsabita Putri Anggani , Ramizah Rifdah , Sri Wahyuni , Emma Yuliani , Arriel Fadhilah
Increasing human activities and improper waste disposal will cause microplastic pollution in surface water. This study analyzed the abundance and characteristics of microplastics, pollution index based on water quality and its relationship with microplastic pollution, and the potential ecological risk of microplastics along the Tambakoso River which is influenced by various land uses of housing, industry, agriculture, and ponds from 16 sampling points. The average abundance of microplastics in the river was 91.80 particles/L. The Kruskal Wallis test showed that there were significant differences between microplastic pollution at each sampling location (Pvalue <0.05). In general, microplastics were mostly found in the form of fragments (48.36 %), transparent color (73.81 %), SMP size (<1 mm) (81.6 %), and dominated by PVC and nylon polymers. However, the characteristics of microplastics at each sampling location varied. The water quality pollution index value showed a slightly polluted category at most points. Redundancy analysis (RDA) showed that the characteristics of the shape and color of microplastics correlated with water quality parameters. The potential ecological risk based on microplastic pollution showed minor, moderate, and high categories at points with industrial land use. This indicates that the distribution of microplastics is closely related to human activities in the area. The level of ecological risk from microplastics depends on the percentage of each plastic polymer, along with its abundance in the environment. This study offers an important basis for designing efficient countermeasures to reduce microplastic pollution and improve water quality in surface waters.
{"title":"Assessment of the water quality pollution index and ecological risk of microplastic pollution along the Tambakoso River in Surabaya, Indonesia","authors":"Riyanto Haribowo , Rizky Almarendra Wirawan Putra , Muchammad Ja'far Shiddik , Tsabita Putri Anggani , Ramizah Rifdah , Sri Wahyuni , Emma Yuliani , Arriel Fadhilah","doi":"10.1016/j.jconhyd.2024.104457","DOIUrl":"10.1016/j.jconhyd.2024.104457","url":null,"abstract":"<div><div>Increasing human activities and improper waste disposal will cause microplastic pollution in surface water. This study analyzed the abundance and characteristics of microplastics, pollution index based on water quality and its relationship with microplastic pollution, and the potential ecological risk of microplastics along the Tambakoso River which is influenced by various land uses of housing, industry, agriculture, and ponds from 16 sampling points. The average abundance of microplastics in the river was 91.80 particles/L. The Kruskal Wallis test showed that there were significant differences between microplastic pollution at each sampling location (Pvalue <0.05). In general, microplastics were mostly found in the form of fragments (48.36 %), transparent color (73.81 %), SMP size (<1 mm) (81.6 %), and dominated by PVC and nylon polymers. However, the characteristics of microplastics at each sampling location varied. The water quality pollution index value showed a slightly polluted category at most points. Redundancy analysis (RDA) showed that the characteristics of the shape and color of microplastics correlated with water quality parameters. The potential ecological risk based on microplastic pollution showed minor, moderate, and high categories at points with industrial land use. This indicates that the distribution of microplastics is closely related to human activities in the area. The level of ecological risk from microplastics depends on the percentage of each plastic polymer, along with its abundance in the environment. This study offers an important basis for designing efficient countermeasures to reduce microplastic pollution and improve water quality in surface waters.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104457"},"PeriodicalIF":3.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142604969","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}
Pub Date : 2024-11-01DOI: 10.1016/j.jconhyd.2024.104449
V.C. Deivayanai, S. Karishma, P. Thamarai, R. Kamalesh, A. Saravanan, P.R. Yaashikaa, A.S. Vickram
Plastic pollution is an extreme environmental threat, necessitating novel restoration solutions. The present investigation investigates the integration of machine learning (ML) techniques with catalytic degradation processes to improve plastic waste management. Catalytic degradation is emphasized for its efficiency and selectivity, while several machine learning techniques are assessed for their capacity to enhance these processes. The review goes into ML applications for forecasting catalyst performance, determining appropriate reaction conditions, and refining catalyst design to improve overall process performance. Briefing about the reinforcement, supervised, and unsupervised learning algorithms that handle all complex data and parameters is explained. A techno-economic study is provided, evaluating these ML-driven system's performance, affordability, and environmental sustainability. The paper reviews how the novel method integrating ML with catalytic degradation for plastic cleanup might alter the process, providing new insights into scalable and sustainable solutions. This review emphasizes the usefulness of these modern strategies in tackling the urgent problem of plastic pollution by offering a comprehensive examination.
塑料污染是一种极端的环境威胁,需要新颖的修复解决方案。本研究调查了机器学习(ML)技术与催化降解过程的整合,以改善塑料废物管理。本研究强调催化降解的效率和选择性,同时对几种机器学习技术进行了评估,看它们是否有能力加强这些过程。综述深入探讨了机器学习在预测催化剂性能、确定合适的反应条件以及改进催化剂设计以提高整体工艺性能方面的应用。还简要介绍了处理所有复杂数据和参数的强化学习、监督学习和无监督学习算法。论文还提供了一项技术经济研究,对这些 ML 驱动系统的性能、经济性和环境可持续性进行了评估。论文回顾了将 ML 与塑料净化催化降解相结合的新方法如何改变工艺,为可扩展和可持续的解决方案提供了新的见解。本综述通过全面考察,强调了这些现代策略在解决塑料污染这一紧迫问题方面的实用性。
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Pub Date : 2024-11-01DOI: 10.1016/j.jconhyd.2024.104451
Yukari Imoto
The assumption of local equilibrium, especially in test standards for assessing the leaching of hazardous substances from materials, is crucial for the use of test results and the robustness of testing. However, previous studies of contact time conditions in percolation test standard have evaluated equilibrium and robustness separately. Therefore, this study tests the assumption of local equilibrium in the up-flow percolation test, standardized as ISO 21268-3 in 2019, and discusses the relationship between the similarity of test results and degree of equilibrium. Thus, we conducted approximately 6000 numerical simulations in total with varying leaching parameters to determine breakthrough curves (BTCs) for the substances investigated by the test standard. The results showed that the two BTCs for the longest and shortest contact time conditions within the standard test were identical over a wide range of parameters, supporting the robustness of the standard test. Interestingly, identical BTCs occur in equilibrium or near-equilibrium and nonequilibrium leaching. This finding indicates the need to reconsider the conventional interpretation that equilibrium is reached when test results with different contact time conditions appear identical and encourages efforts to develop procedures to verify equilibrium leaching.
局部平衡的假设,尤其是在评估材料中有害物质沥滤的测试标准中,对于测试结果的使用和测试的稳健性至关重要。然而,以往对渗滤测试标准中接触时间条件的研究是将平衡和稳健性分开评估的。因此,本研究测试了 2019 年标准化为 ISO 21268-3 的上流式渗滤测试中的局部平衡假设,并讨论了测试结果的相似性与平衡程度之间的关系。因此,我们总共进行了约 6000 次不同浸出参数的数值模拟,以确定测试标准所研究物质的突破曲线(BTC)。结果表明,标准测试中接触时间最长和最短条件下的两条突破曲线在很大的参数范围内是相同的,这证明了标准测试的稳健性。有趣的是,在平衡或接近平衡和非平衡沥滤条件下会出现相同的 BTC。这一发现表明,有必要重新考虑传统的解释,即当不同接触时间条件下的测试结果看起来相同时,就已经达到了平衡,并鼓励人们努力开发验证平衡沥滤的程序。
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Pub Date : 2024-11-01DOI: 10.1016/j.jconhyd.2024.104452
Siyuan Qiang , Xiaoqing Shi , André Revil , Xueyuan Kang , Christopher Power
The combined application of direct current (DC) resistivity and induced polarization (IP) methods, referred to as combined DCIP method, has gained popularity for characterizing the critical zone dynamic processes such as dense non-aqueous phase liquids (DNAPLs) spreading at contaminated sites. Large-scale DCIP surveys typically require considerable durations, necessitating optimized survey designs to enhance survey resolution while controlling time and labor costs. However, to date, approaches to optimize geoelectrical survey design have focused solely on DC applications, and the efficiency of optimized survey designs for combined DCIP is yet to be investigated. Moreover, as subsurface heterogeneity would impact the geophysical observations, most field-scale numerical DCIP studies have still been conducted at artificial sites that lacked realistic aquifer heterogeneity, which could affect the validity of the DCIP survey evaluations. In this work, a virtual geoenvironmental field site based on high-resolution real aquifer analog was created to simulate a DNAPL evolution scenario with simultaneous monitoring by DCIP survey, employing both the optimized survey design and popular non-optimized survey designs (Wenner, Wenner-Schlumberger, Dipole-Dipole arrays). Results show that the optimized survey with prior information improves the monitoring accuracy of DNAPL source zone (SZ) by 8 to 19 % with respect to different DCIP characteristics (conductivity, chargeability, normalized chargeability, and relaxation time). Another ideal numerical test indicates that the optimized survey shows up to an 83 % reduction in measurement time compared to the conventional survey, while maintaining the same subsurface image resolution. Additionally, the optimized surveys designed without or with limited prior information were also shown to be more efficient than conventional survey for imaging the entire subsurface space. The findings in this study highlight the immense potential of optimized survey design methods for enhancing the efficiency of DCIP surveys on subsurface contaminants and hydrological processes.
{"title":"Optimized survey design for the joint use of direct current resistivity and induced polarization: Monitoring of DNAPL source zone evolution at a virtual field site","authors":"Siyuan Qiang , Xiaoqing Shi , André Revil , Xueyuan Kang , Christopher Power","doi":"10.1016/j.jconhyd.2024.104452","DOIUrl":"10.1016/j.jconhyd.2024.104452","url":null,"abstract":"<div><div>The combined application of direct current (DC) resistivity and induced polarization (IP) methods, referred to as combined DCIP method, has gained popularity for characterizing the critical zone dynamic processes such as dense non-aqueous phase liquids (DNAPLs) spreading at contaminated sites. Large-scale DCIP surveys typically require considerable durations, necessitating optimized survey designs to enhance survey resolution while controlling time and labor costs. However, to date, approaches to optimize geoelectrical survey design have focused solely on DC applications, and the efficiency of optimized survey designs for combined DCIP is yet to be investigated. Moreover, as subsurface heterogeneity would impact the geophysical observations, most field-scale numerical DCIP studies have still been conducted at artificial sites that lacked realistic aquifer heterogeneity, which could affect the validity of the DCIP survey evaluations. In this work, a virtual geoenvironmental field site based on high-resolution real aquifer analog was created to simulate a DNAPL evolution scenario with simultaneous monitoring by DCIP survey, employing both the optimized survey design and popular non-optimized survey designs (Wenner, Wenner-Schlumberger, Dipole-Dipole arrays). Results show that the optimized survey with prior information improves the monitoring accuracy of DNAPL source zone (SZ) by 8 to 19 % with respect to different DCIP characteristics (conductivity, chargeability, normalized chargeability, and relaxation time). Another ideal numerical test indicates that the optimized survey shows up to an 83 % reduction in measurement time compared to the conventional survey, while maintaining the same subsurface image resolution. Additionally, the optimized surveys designed without or with limited prior information were also shown to be more efficient than conventional survey for imaging the entire subsurface space. The findings in this study highlight the immense potential of optimized survey design methods for enhancing the efficiency of DCIP surveys on subsurface contaminants and hydrological processes.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104452"},"PeriodicalIF":3.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568108","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}