Journal of contaminant hydrology最新文献

{"title":"Insight into the relationship between similarity and the degree of equilibrium of contaminant release curves through numerical simulations","authors":"Yukari Imoto","doi":"10.1016/j.jconhyd.2024.104451","DOIUrl":"10.1016/j.jconhyd.2024.104451","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104451"},"PeriodicalIF":3.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142545793","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":"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 ,&nbsp;Xiaoqing Shi ,&nbsp;André Revil ,&nbsp;Xueyuan Kang ,&nbsp;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}

{"title":"Characterization of microplastics in soil, leachate and groundwater at a municipal landfill in Rayong Province, Thailand","authors":"Wanlapa Wisitthammasri ,&nbsp;Phatchareeporn Promduang ,&nbsp;Srilert Chotpantarat","doi":"10.1016/j.jconhyd.2024.104455","DOIUrl":"10.1016/j.jconhyd.2024.104455","url":null,"abstract":"<div><div>Recent years have witnessed a dramatic increase in global plastic production, leading to heightened concerns over microplastics (MPs) contamination as a significant environmental challenge. MP particles are ubiquitously distributed across both continental and marine ecosystems. Given the paucity of research on MPs in Thailand, particularly regarding MPs contamination in terrestrial environments, this study focused on investigating the distribution and characteristics of MPs in a landfill area. We collected 15 soil samples, 2 leachate samples, and 7 groundwater samples from both inside and outside a municipal landfill situated in the urbanized coastal region of Rayong Province. Our findings revealed variability in MPs concentration across different sample types. In soil, the MP count ranged from 240 to 26,100 pieces per kg of dry soil, 58.71 % of all sample sizes are lower than 0.5 mm. Similarly, the size found in the leachate sample, and the average MP in the leachate samples was 139 pieces per liter of MPs. The groundwater samples showed a fluctuation in MPs count from 18 to 94 pieces per liter, and the size of MPs ranged mostly from 0.5 to 1 mm. The predominant forms of MPs identified were sheets, followed by fragments, fibers, and granules. According to μ-FTIR analysis, the majority of the MPs were composed of polyethylene and polypropylene, commonly used in plastic packaging and ropes. The observed high concentrations and extensive distribution of MP contamination underscore the urgency for further studies and effective management strategies to mitigate the adverse impacts of this pollution on various organisms and ecosystems.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104455"},"PeriodicalIF":3.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142604971","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 semi-probabilistic Bayesian method to identify the number and location of potential sources in 3D unconfined aquifer using limited observed concentration","authors":"Bandaru Goutham Rajeev Gandhi ,&nbsp;Rajib Kumar Bhattacharjya","doi":"10.1016/j.jconhyd.2024.104447","DOIUrl":"10.1016/j.jconhyd.2024.104447","url":null,"abstract":"<div><div>Source identification of a contaminant has always been challenging for accurately modeling groundwater transport. Source identification problems are classified into several parts, such as identifying the location of contamination, the strength of contamination, the time the contaminant is introduced into the groundwater, and the duration of its activity. Identifying the sources considering all the parts as variables increases the computational complexity. Reducing the number of variables in source identification problems is necessary for a swift solution through optimization approaches. The most challenging variable in source identification modeling is the location of contamination, as it is a discrete variable for almost all the numerical solutions of groundwater models. In this research study, we have created a methodology to narrow the location of contamination from a random distribution throughout the aquifer to a reasonable number of probable locations. Although methods to identify the location of contamination were devised earlier, we have attempted an approach of combining a particle tracking approach with Bayesian method of updating the probabilities as a novel approach, where the observation data is limited. We have considered the aquifer parameters and observation well data and devised a method with a Lagrangian approach to particle movement to identify the potential source locations. We have refined the source locations to a narrower probability distribution using the Bayesian method of updating the probability through new information of refined grid space. We have tested the models to identify the potential sources with different hypothetical problems and identified the sources in advective dominant transport with an average probability of 0.53, diffusion dominant transport with an average probability of 0.62, heterogenous soils with an average probability of 0.99, anisotropic aquifer with an average probability of 0.91, and aquifer with irregular boundary with an average probability of 0.96 to identify the location nearest to the actual contaminant source. The results are satisfactory in identifying the number of potential sources with an accuracy of 88 % (15 identified out of 17 sources with a probability greater than 0.4) and their locations in the aquifer with a probability of 0.223 for exact location identification. The probability of finding a source nearest to the actual location is 0.745 at an average distance of 11.6 m from the actual source location.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104447"},"PeriodicalIF":3.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142501312","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":"Microplastics in wastewater plants: A review of sources, characteristics, distribution and removal technologies","authors":"Zhihao Hu,&nbsp;Yongjun Sun,&nbsp;Jun Zhou,&nbsp;Wenquan Sun,&nbsp;Kinjal J. Shah","doi":"10.1016/j.jconhyd.2024.104448","DOIUrl":"10.1016/j.jconhyd.2024.104448","url":null,"abstract":"<div><div>Microplastics (MPs) are widespread in everyday life, and since wastewater treatment plants (WWTPs) serve as an important route for MPs to enter natural water bodies, a thorough understanding of the distribution and removal of MPs in wastewater treatment plants is of great importance. This article provides a comprehensive overview of the measured distribution of MPs and the current status of their removal in wastewater treatment plants. The main sources of MPs in wastewater treatment plants are personal care products in domestic wastewater, textile clothing and industrial wastewater made from plastics, textile factories and the friction of road tires. The MPs that entered the sewage treatment plant were predominantly in the form of fibers, fragments, granular MPs and other types of MPs. The size of MPs is divided into three categories: &lt;0.5 mm, 0.5–1 mm and 1–5 mm. At all treatment stages in wastewater plants, 56.8–88.4 % of MPs are removed in primary treatment, but the primary sedimentation and degreasing stages remove most MPs. The efficiency of the activated sludge process for secondary treatment is inconsistent and is generally between 42.1 and 99.2 %. The coagulation, filtration and disinfection stages of tertiary treatment all have some MPs removal capacity. In addition, novel removal technologies are also described, such as modified filtration technology, membrane separation technology, electroflocculation, sol-gel and photocatalysis. These novel removal technologies can further limit the entry of microplastics into natural water bodies through sewage treatment plants and improved sewage treatment processes help reduce the risk of MPs entering the natural environment through sewage treatment plants. This article will provide reference for the distribution and removal of microplastics in various levels of WWTPs.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104448"},"PeriodicalIF":3.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142501314","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":"Patterns of spatiotemporal variations in the hydrochemistry and controlling factors of bedrock aquifers in the northern region of the Linhuan mining area","authors":"Miao Zhang ,&nbsp;Luwang Chen ,&nbsp;Xiaowei Hou ,&nbsp;Yongsheng Hu ,&nbsp;Jie Zhang ,&nbsp;Jun Li ,&nbsp;Xiaoxi Yin ,&nbsp;Xiaoping Shi ,&nbsp;Xinyue Cai","doi":"10.1016/j.jconhyd.2024.104450","DOIUrl":"10.1016/j.jconhyd.2024.104450","url":null,"abstract":"<div><div>Systematically studying the hydrochemical evolution of bedrock groundwater in mining areas during mining process is crucial for effective groundwater resource management and coal mine production. The spatiotemporal characteristics and hydrochemical evolution patterns of the Permian fractured sandstone aquifer (PA) and the Carboniferous Taiyuan Formation limestone aquifer (CTA), both of which are directly associated with coal mining in the northern Linhuan mining area, China, were investigated using multivariate statistical analyses, hydrochemical graphical methods, ion ratio analysis, and a conceptual model. 72 groundwater samples, collected before and after mining, were classified into four groups by hierarchical cluster analysis (HCA). Principal component analysis (PCA) and ion ratio analysis indicated that water-rock interactions involve mineral dissolution (carbonates, gypsum, dolomite, silicates), cation exchange, and common ion effects. Hydrochemical evolution is influenced by bedrock paleotopography, aquifer hydraulic conductivity, and mining drainage. Paletopographic differences significantly influence water-rock interactions and spatial variability in hydrochemistry, with ion concentrations in groundwater increasing as paleotopographic elevation decreases. The pattern of hydraulic conductivity reflects the control exerted by variations in aquifer characteristics on mineral dissolution, leading to minor changes in hydrochemical characteristics. Mining activities disrupt the aquifer's reducing environment, resulting in a significant increase in groundwater SO₄²⁻ concentration. These findings provide insights and a solid theoretical foundation for studying the hydrochemical variations patterns of groundwater and these control mechanisms in the hidden coal fields of North China.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104450"},"PeriodicalIF":3.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142501315","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":"Determining the evaporation and evolution of surface water in a large catchment using isotopes and multiple models","authors":"Xiang Dong ,&nbsp;Xing Chen ,&nbsp;Fazhi Xie ,&nbsp;Liugen Zheng ,&nbsp;Zihan Zhang ,&nbsp;Xinyi Fu ,&nbsp;Tianqi Ma","doi":"10.1016/j.jconhyd.2024.104446","DOIUrl":"10.1016/j.jconhyd.2024.104446","url":null,"abstract":"<div><div>The evolution and formation mechanisms of chemical components in surface water can reflect changes in the geological background of a basin and the extent of human interference. The Yangtze River basin is the largest water source area in China, yet its main ion sources and formation mechanisms are not fully understood. This study uses a combination of hydrochemistry, stable isotopes (δ¹⁸O, δD), the Craig-Gordon model, and the APCS-MLR model to quantitatively assess the water source replenishment and evaporation intensity of surface water in the Yangtze River. The study reveals the primary ion sources and controlling factors of surface water in the Yangtze River. The results show that the hydrochemical type in the upstream is mainly HCO₃⁻-Ca²⁺ and Na⁺-K⁺, while in the midstream and downstream it is primarily HCO₃⁻-Ca²⁺ and SO₄²⁻-Ca²⁺. The evolution of hydrochemical types is mainly controlled by rock weathering and human inputs. The surface water sources in the Yangtze River are directly replenished by precipitation, with the evaporation ratio in the upstream (0.66) being higher than in the midstream (0.63) and downstream (0.47). The lc-excess in the upstream (−0.32 ‰) is lower than in the midstream (1.21 ‰) and downstream (−0.27 ‰), indicating more intense evaporation in the upstream. The hydrochemical composition of the Yangtze River surface water mainly comes from geological factors (80.5 %), industrial factors (11.1 %), agricultural factors (6.4 %), and unknown factors (2.0 %). This study enhances the understanding of the chemical composition, water source replenishment, ion sources, and evolution mechanisms of the Yangtze River surface water, providing a basis for maintaining water quality and sustainable development in the Yangtze River basin.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104446"},"PeriodicalIF":3.5,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142501313","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":"Feasibility evaluation of a blended cover with activated carbon for in-situ stabilization of DDT in sediment","authors":"Yeo-Myoung Cho,&nbsp;Brooke J. Pauken,&nbsp;Anna E. Tovkach,&nbsp;Oliver B. Fringer,&nbsp;Stephen G. Monismith,&nbsp;Richard G. Luthy","doi":"10.1016/j.jconhyd.2024.104445","DOIUrl":"10.1016/j.jconhyd.2024.104445","url":null,"abstract":"<div><div>Activated carbon (AC) sediment amendment is an in-situ remediation technology in which the applied AC immobilizes organic contaminant flux from sediments, thereby reducing contaminant bioavailability and associated risks. While various studies have demonstrated the feasibility of in-situ AC treatment, hesitation to apply this technology exists due to limited experience under field-specific scour conditions and hydrodynamic forces. To address this concern, we conducted a feasibility study for an AC-blended cover at the Lauritzen Channel of the United Heckathorn Superfund Site in Richmond, California, United States, which was contaminated with dichlorodiphenyltrichloroethane and its metabolites (DDx) as well as dieldrin. Vessel activities causing sediment disturbance were identified as key factors for remedy selection. A blended cover with AC and coarse materials was designed to withstand varied hydrodynamic conditions and AC stability was tested in a current flume. The cover comprised medium-size gravel (D₅₀ = 15 mm, D₉₀ = 19 mm) with 4 % granular AC by weight. Flume erosion studies showed minimal AC loss (1–2 % of total AC) under shear forces of 9–31 Pa, which was equivalent to or exceeded the estimated worst-case erosional conditions in the channel induced by a hypothetical, stationary tugboat propelling at high power thrust. The treatability performance of the engineered blended cover design was evaluated through mesocosm studies using site sediment and various cover options. Post-treatment assessments on days 5 and 145 showed rapid reductions in freely dissolved (C_free) DDx and dieldrin in the blended cover layers and surface water. For example, by day 145, C_free DDx was reduced by over 98 %, meeting US EPA remedial goals for the site. It is concluded that the combination of both stability and performance testing demonstrates that an engineered blended cover-AC design would be a feasible remedial option at the site, and that this testing approach can be applied to evaluate in-situ treatment in other sediment cleanup activities.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104445"},"PeriodicalIF":3.5,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446447","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}

{"title":"Impact of humic acid on iron (oxyhydr)oxide transport in the presence of phosphate in saturated porous media","authors":"Tufail Shah ,&nbsp;Kang Zhao ,&nbsp;Yingjie Yin ,&nbsp;Jianying Shang","doi":"10.1016/j.jconhyd.2024.104444","DOIUrl":"10.1016/j.jconhyd.2024.104444","url":null,"abstract":"<div><div>The subsurface flow of particular phosphate (P) has been recently regarded as a vital P transport path. Humic acid (HA) and P usually coexist in the natural environment and show a strong affinity to iron (Fe) (oxyhydr)oxide. The impact of P and HA on Fe (oxyhydr)oxide stability and transport is critical for evaluating the vertical transport of particular P and biogeochemical processes of Fe and P. This study investigated the effect of inorganic (IP) and organic (OP) phosphate on the stability and transport of ferrihydrite and goethite with HA through stability tests and column experiments. The adsorption of IP or OP on Fe (oxyhydr)oxide enhanced the stability and transport of Fe (oxyhydr)oxide, and OP showed a stronger enhancement than IP due to its stronger binding capacity and more negative surface. Compared with ferrihydrite, goethite had fewer adsorption sites for IP or OP and showed strong stability and transport at low IP (50 μM) or OP (10 μM) concentration. HA decreased IP or OP adsorption on Fe (oxyhydr)oxide through competition adsorption and electrostatic repulsion. The formed ternary phosphate-Fe (oxyhydr)oxide-HA complex showed a more negative surface and strong stability and transport. Our findings provide direct insights into the distinct role of IP and OP on Fe (oxyhydr)oxide stability and transport in the presence of HA, which provides essential information for evaluating the transport of particular Fe (oxyhydr)oxide-facilitated P in soils and subsurface environments rich in iron, phosphate, and dissolved carbon.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104444"},"PeriodicalIF":3.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441899","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":"Time-lapse dielectric properties monitoring of the flow cell during DNAPL contamination and remediation processes by full-waveform inversion of GPR data using particle swarm optimization: A laboratory study","authors":"İsmail Kaplanvural ,&nbsp;Ertan Pekşen ,&nbsp;Nihat Hakan Akyol ,&nbsp;Doğukan Durdağ","doi":"10.1016/j.jconhyd.2024.104443","DOIUrl":"10.1016/j.jconhyd.2024.104443","url":null,"abstract":"<div><div>This study presents the monitoring of the contamination and remediation processes of an aquifer system using the ground-penetrating radar (GPR) method. To achieve this, periodic GPR measurements were performed on a flow cell, which was established to simulate aquifer contamination and remediation scenarios. The exterior of the flow cell was made of plexiglas, and a small hole was created at the top center to inject Dense Non-aqueous Phase Liquid (DNAPL) contamination. To study contaminant distribution and remediation processes, DNAPL Trichloroethylene (TCE) was used as the groundwater contaminant. Methyl-beta-cyclodextrin (MCD) was used as remediation agent. The interior of the flow cell was packed with two different sand grain size distributions: low permeability sand along the bottom and a higher permeability sand along the top. Common offset GPR measurements were performed along the top plane of the flow cell. The GPR measurements were conducted periodically over a total duration of 66 days, encompassing the phases prior to injecting DNAPL TCE, after injection of DNAPL TCE, and during the remediation process using MCD. Time-lapse GPR data were analyzed using 1D and 2D plots. In addition, to evaluate and monitor the contamination and remediation processes within the flow cell, central traces of the time-lapse GPR dataset were inverted by full-waveform inversion to estimate the dielectric properties of the layers and the depth by Particle Swarm Optimization (PSO). To utilize PSO, a forward model calculation using 1D finite difference in time domain adapted to PSO algorithm to generate theoretical GPR traces to compare the theoretical model GPR traces to the measured GPR traces as a “goodness of fit” metric. The electrical conductivity, relative dielectric permittivity, relative magnetic permeability, and depth of the layer were estimated by PSO of the GPR data. The results of the inversion process indicated a significant change in the estimated electrical conductivity values for the post TCE DNAPL contamination stage and the remediation stage. In addition, to support the inversion results, contaminant mass removal was quantified using moment analysis from dissolved-phase contaminant concentrations collected from the flow cell over time. According to the mass recovery calculation by moment analysis, which was collected via an outlet from the flow cell, approximately 38 % of the injected DNAPL TCE mass was removed by enhanced dissolution from the representative aquifer domain of the flow cell during the remediation stage of the experiment.</div></div>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"267 ","pages":"Article 104443"},"PeriodicalIF":3.5,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142417645","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}