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The chlor-alkali industry (CAI) is crucial for global chemical production; however, its operation has led to widespread heavy metal (HM) contamination at numerous sites, which has not been thoroughly investigated. This study analysed 122 soil and groundwater samples from a typical CAI site in Kaifeng, China. Our aim was to assess the ecological and health risks, identify the sources, and examine the migration characteristics of HMs at this site using Monte Carlo simulation, absolute principal component score-multiple linear regression (APCS-MLR), and the potential environmental risk index (Ei). Our findings revealed that the exceedance rates for Cd, Pb, Hg, and Ni were 71.96%, 45.79%, 49.59%, and 65.42%, respectively. Mercury (Hg) displayed the greatest coefficient of variation across all the soil layers, indicating a significant anthropogenic influence. Cd and Hg were identified as having high and extremely high potential environmental risk levels, respectively. The spatial distributions of the improved Nemerow index (INI), total ecological risk (Ri), and HM content varied considerably, with the most contaminated areas typically associated with the storage of raw and auxiliary materials. Surface aggregation and significant vertical transport were noted for HMs; As and Ni showed substantial accumulation in subsoil layers, severely contaminating the groundwater. Self-organizing maps categorized the samples into two different groups, showing strong positive correlations between Cd, Pb, and Hg. The APCS-MLR model suggested that industrial emissions were the main contributors, accounting for 60.3% of the total HM input. Elevated hazard quotient values for Hg posed significant noncarcinogenic risks, whereas acceptable levels of carcinogenic risk were observed for both adults (96.60%) and children (97.83%). This study significantly enhances historical CAI pollution data and offers valuable insights into ongoing environmental and health challenges.

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Fluoroquinolone (FQ) antibiotics have become a subject of growing concern due to their increasing presence in the environment, particularly in the soil and groundwater. This review provides a comprehensive examination of the attributes, prevalence, ecotoxicity, and remediation approaches associated with FQs in environmental matrices. The paper discusses the physicochemical properties that influence the fate and transport of FQs in soil and groundwater, exploring the factors contributing to their prevalence in these environments. Furthermore, the ecotoxicological implications of FQ contamination in soil and aquatic ecosystems are reviewed, shedding light on the potential risks to environmental and human health. The latter part of the review is dedicated to an extensive analysis of remediation approaches, encompassing both in-situ and ex-situ methods employed to mitigate FQ contamination. The critical evaluation of these remediation strategies provides insights into their efficacy, limitations, and environmental implications. In this investigation, a correlation between FQ antibiotics and climate change is established, underlining its significance in addressing the Sustainable Development Goals (SDGs). The study further identifies and delineates multiple research gaps, proposing them as key areas for future investigational directions. Overall, this review aims to consolidate current knowledge on FQs in soil and groundwater, offering a valuable resource for researchers, policymakers, and practitioners engaged in environmental management and public health.

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Nitrogen fertilizer supports global food production, but its manufacturing results in substantial ammonia nitrogen (AN) contaminated sites which remain largely unexplored. In this study, ten representative AN contaminated sites were investigated, covering a wide range of subsurface pH, temperature, and AN concentration. A total of 7232 soil samples and 392 groundwater samples were collected to determine the concentration levels, migration patterns, and accurate health risks of AN. The results indicated that AN concentrations in soil and groundwater reached 12700 mg/kg and 12600 mg/L, respectively. AN concentrations were higher in production areas than in non-production areas, and tended to migrate downward from surface to deeper soil. Conventional risk assessment based on AN concentration identified seven out of the ten sites presenting unacceptable risks, with remediation costs and CO2 emissions amounting to $1.67 million and 17553.7 tons, respectively. A novel risk assessment model was developed, which calculated risks based on multiplying AN concentration by a coefficient fNH3 (the ratio of NH3 to AN concentration). The mean fNH3 values, primarily affected by subsurface pH, varied between 0.02 and 0.25 across the ten sites. This new model suggested all investigated sites posed acceptable health risks related to AN exposure, leading to their redevelopment without AN-specific remediation. This research offers a thorough insight into AN contaminated site, holds great realistic significance in alleviating global economic and climate pressures, and highlights the need for future research on refined health risk assessments for more contaminants.

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Assessing human health risks associated with inhalation exposure of volatile chemical substances (VCSs) volatilized from contaminated soil requires quantitative evaluation of volatilization fluxes (VFs) and an understanding of how environmental factors impact VF generation. We developed a numerical model that considers advection-dispersion and VCSs volatilization in unsaturated soil, enabling VF prediction through parameter optimization using soil column tests. We conducted parametric analyses to assess how key parameters, such as soil particle size, contamination depth, temperature, and surface soil thickness affect VF generation. By analyzing VCS transport near the ground surface, we uncovered the mechanisms underlying VF generation. We also identified characteristic differences in VF generation behavior linked to soil particle size and gas saturation at the ground surface. Under specific soil particle size conditions, significant VF generation occurred even when contamination was deep underground. This was primarily observed when capillary effect was pronounced, and VCSs continued to be supplied to the ground surface through upward advection. Considering the significant impact of VF generation on human health, our parametric study provides valuable insights into relationships between different parameters and VF behavior, especially under varying ground surface temperatures and surface soil thicknesses. This study contributes to developing effective remediation and risk-reduction strategies. ENVIRONMENTAL IMPLICATION: This research examines the environmental implications of volatile chemical substances (VCSs), including hazardous materials like benzene and trichloroethylene, in contaminated soil. VCSs pose health risks when they volatilize from soil. The study quantifies volatilization fluxes (VF) and elucidates the environmental factors affecting VF generation. These findings are vital for effective environmental management. By comprehending the mechanisms governing VF generation, particularly regarding soil properties like particle size, this research enhances the effectiveness of soil contamination remediation and risk reduction. It emphasizes the essential need for a comprehensive VCS assessment in contaminated soils to protect both human health and the environment.

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Biochar-supported nano zero-valent iron (BC@nZVI) is a novel and efficient non-homogeneous activator for persulfate (PS). This study aimed to identify the primary pathways, the degradation mechanism and the performance of phenanthrene (PHE) with PS activated by BC@nZVI (BC@nZVI/PS). BC@nZVI as an activator for PS was prepared by liquid phase reduction method. BC@nZVI was characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffractometer and Fourier transform infrared spectroscopy. The effects of the iron-carbon mass ratio and BC@nZVI dosage were investigated, and a pseudo-first-order kinetic model was used to evaluate the PHE degradation. The results showed that BC supported nZVI and inhibited the agglomeration of nZVI, improving PS's activation efficiency. The optimal iron-carbon mass ratio was determined to be 1:4, accompanied by a dosage of 0.6 g/L of BC@nZVI. During PS activation, nZVI was transformed to Fe2+ and Fe3+, with the majority being Fe3+. The reducibility of nZVI in BC@nZVI enabled the reduction of Fe3+ to Fe2+ to activate PS. Radical quenching and electron paramagnetic resonance (EPR) revealed that the oxidative radicals in the BC@nZVI/PS system were mainly SO4-· and ·OH, where SO4-· was the primary free radical under acidic and neutral conditions and ·OH in alkaline conditions. Additionally, BC@nZVI adsorption had a limited role in PHE removal. This study can provide mechanism insights of PHE degradation in water with BC@nZVI activation of the Na2S2O8 system.

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Sustained-release materials are increasingly being used in the delivery of oxidants for in situ chemical oxidation (ISCO) for groundwater remediation. Successful implementation of sustained-release materials depends on a clear understanding of the mechanism and kinetics of sustained release. In this research, a columnar sustained-release material (PS@PW) was prepared with paraffin wax and sodium persulfate (PS), and column experiments were performed to investigate the impacts of the PS@PW diameter and PS/PW mass ratio on PS release. The results demonstrated that a reduction in diameter led to an increase in both the rate and proportion of PS release, as well as a diminished lifespan of release. The release process followed the second-order kinetics, and the release rate constant was positively correlated with the PS@PW diameter. A matrix boundary diffusion model was utilized to determine the PS@PW diffusion coefficient of the PS release process, and the release lifespan of a material with a length of 500 mm and a diameter of 80 mm was predicted to be more than 280 days. In general, this research provided a better understanding of the release characteristics and kinetics of persulfate from a sustained-release system and could lead to the development of columnar PS@PW as a practical oxidant for in situ chemical oxidation of contaminated aquifers.

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The global industrial structure had undertaken significant changes since the twenty-first century, making a severe problem of chlorobenzene pollution in soil and groundwater (CBsPSG). CBsPSG receives increasing attention due to the high toxicity, persistence, and bioaccumulation of chlorobenzenes. To date, despite the gravity of this issue, no bibliometric analysis (BA) of CBsPSG does exist. This study fills up the gap by conducting a BA of 395 articles related to CBsPSG from the Web of Science Core Collection database using CiteSpace. Based on a comprehensive analysis of various aspects, including time-related, related disciplines, keywords, journal contribution, author productivity, and institute and country distribution, the status, development, and hotspots of research in the field were shown visually and statistically. Moreover, this study has also delved into the environmental behavior and remediation techniques of CBsPSG. In addition, four challenges (unequal research development, insufficient cooperation, deeply mechanism research, and developing new technologies) have been identified, and corresponding suggestions have been proposed for the future development of research in the field. Afterwards, the limitations of BA were discussed. This work provides a powerful insight into CBsPSG, enabling to quickly identify the hotspot and direction of future studies by relevant researchers.

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With the increasing use of plastics, nano- and micro-plastic (NMP) pollution has become a hot topic in the scientific community. Ubiquitous NMPs, as emerging contaminants, are becoming a global issue owing to their persistence and potential toxicity. Compared with studies of marine and freshwater environments, investigations into the sources, transport properties, and fate of NMPs in soil and groundwater environments remain at a primary stage. Hence, the promotion of such research is critically important. Here, we integrate existing information and recent advancements to compile a comprehensive evaluation of the sources and transport properties of NMPs in soil and groundwater environments. We first provide a systematic description of the various sources and transport behaviors of NMPs. We then discuss the theories (e.g., clean-bed filtration and Derjaguin-Landau-Verwey-Overbeek theories) and models (e.g., single-site and dual-site kinetic retention and transport models) of NMP transport through saturated porous media. Finally, we outline the potential limitations of current research and suggest directions for future research. Overall, this review intends to assimilate and outline current knowledge and provide a useful reference frame to determine the sources and transport properties of NMPs in soil and groundwater environments.

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Soil and groundwater contamination has become a key issue in urban redevelopment. It is particularly difficult to use heavy equipment for the remediation of restricted sites or areas contaminated by factories that are still in operation. In this case, horizontal wells are considered a potentially useful technology as they can potentially remediate contamination areas located below buildings and other surface/subsurface obstacles. This research first introduces the principles and advantages and disadvantages of direct push injection, improved slant well, high-pressure rotary jet technology, horizontal reactive media treatment wells, and horizontal directional drilling well. The key aspects for promising in-situ remediation techniques were summarized as remediation well design, remediation agent injection technology and drill pipe and well wall sealing technology. Based on the requirements for key technologies, a novel multi-branch horizontal well in-situ remediation process was proposed, which integrates vertical/horizontal directional drilling, rotary injection, and expansion sealing techniques, and relevant supporting drilling and injecting equipment were developed. A bench test and field test were conducted to test drilling tool performance, drilling accuracy, and injection radius of influence. The results showed that the developed supporting drilling tool met the process requirements and could complete multi-branch horizontal well remediation engineering construction. The deviation between the measured depth and the design depth of the multi-branch horizontal well constructed using this technology was less than 9%, and the deviation between the depth displayed by the guidance instrument and the measured depth was less than 1%. The injection radius of influence in the test field measured from the monitoring wells was greater than or equal to 5 m. The results of this research can provide an effective method for the remediation of contaminated sites.

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Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFSAs), which are the most commonly regulated and most widely concerned per- and polyfluoroalkyl substances (PFAS) have received increasing attention on a global scale due to their amphiphilicity, stability, and long-range transport. Thus, understanding the typical PFAS transport behavior and using models to predict the evolution of PFAS contamination plumes is important for evaluating the potential risks. In this study, the effects of organic matter (OM), minerals, water saturation, and solution chemistry on the transport and retention of PFAS were investigated, and the interaction mechanism between long-chain/short-chain PFAS and the surrounding environment was analyzed. The results revealed that high content of OM/minerals, low saturation, low pH, and divalent cation had a great retardation effect on long-chain PFAS transport. The retention caused by hydrophobic interaction was the prominent mechanism for long-chain PFAS, whereas, the retention caused by electrostatic interaction was more relevant for short-chain PFAS. Additional adsorption at the air-water and nonaqueous-phase liquids (NAPL)-water interface was another potential interaction for retarding PFAS transport in the unsaturated media, which preferred to retard long-chain PFAS. Furthermore, the developing models for describing PFAS transport were investigated and summarized in detail, including the convection-dispersion equation, two-site model (TSM), continuous-distribution multi-rate model, modified-TSM, multi-process mass-transfer (MPMT) model, MPMT-1D model, MPMT-3D model, tempered one-sided stable density transport model, and a comprehensive compartment model. The research revealed PFAS transport mechanisms and provided the model tools, which supported the theoretical basis for the practical prediction of the evolution of PFAS contamination plumes.

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The mechanistic study of soil and groundwater remediation in petroleum contaminated lands significantly demands rapid qualitative and quantitative identification of petroleum substances. However, most traditional detection methods cannot provide the on-site or in-situ information of petroleum compositions and contents simultaneously even with multi-spot sampling and complex sample preparation. In this work, we developed a strategy for the on-site detection of petroleum compositions and in-situ monitoring of petroleum contents in soil and groundwater using dual-excitation Raman spectroscopy and microscopy. The detection time was 0.5 h for the Extraction-Raman spectroscopy method and one minute for the Fiber-Raman spectroscopy method. The limit of detection was 94 ppm for the soil samples and 0.46 ppm for the groundwater samples. Meanwhile, the petroleum changes at the soil-groundwater interface were successfully observed by Raman microscopy during the in-situ chemical oxidation remediation processes. The results revealed that hydrogen peroxide oxidation released petroleum from the interior to the surface of soil particles and then to groundwater during the remediation process, while persulfate oxidation only degraded petroleum on the soil surface and in groundwater. This Raman spectroscopic and microscopic method can shed light on the petroleum degradation mechanism in contaminated lands, and facilitate the selection of suitable soil and groundwater remediation plans.

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An experimental and computational investigation of in situ chemical oxidation (ISCO) of weathered diesel fuel in soil columns was undertaken to validate a reactive-transport model capable of predicting contaminant mass reduction from a residual source zone. Reactivity tests with contaminated groundwater in batch reactors were used to estimate a priori the kinetic parameters of a phenomenological model of the oxidation of petroleum hydrocarbon (PHC) mixture fractions. The transport model, which incorporated groundwater flow, dissolution of main PHC fractions, and homogeneous reaction in the aqueous phase, was subsequently validated against experimental data of ISCO in soil columns using repetitive treatments with unactivated and alkaline-activated persulfate. No significant effect of the initial concentration of persulfate on the remediation performance was observed in the batch system, but alkaline activation significantly improved performance. The alkaline-activated persulfate treatment achieved ∼80% removal of the initial NAPL mass in soil columns. The combination of models and experiments described herein should enable the rational design of field-scale advanced oxidation strategies for the removal of weathered petroleum hydrocarbons. This expectation was supported by a comprehensive demonstration study at a historical site contaminated by weathered diesel fuel present as a residual source within the soil and dissolved within groundwater.

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To evaluate the effectiveness of biostimulation in remediating soil-free groundwater and groundwater with soil, experiments were conducted using soil and groundwater samples that were contaminated with sulfolane. The main objective was to characterize the differences in sulfolane removal efficiency and biotoxicity between in situ soil-free groundwater and groundwater with soil and different concentrations of dissolved oxygen (1 mg/L and 5 mg/L) and various nutrient salts (in situ and spiked). Optimizing the nutrient salt conditions improved the removal efficiency of sulfolane by 1.8-6.5 that under in situ nutrient salt conditions. Controlling the dissolved oxygen concentration enhanced the efficiency of removal of sulfolane by 1.5-4.5 times over that at the simulated in situ dissolved oxygen concentration, suggesting that the degradation of sulfolane by indigenous microorganisms requires nutrient salts more than it requires dissolved oxygen. Biotoxicity data showed that the luminescence inhibition of Aliivibrio fischeri by sulfolane was lower in the biostimulated samples than in the pre-treated samples. Biostimulation reduced the biotoxicity of the treated samples by 42-51%, revealing that it was effective in removing sulfolane and reducing biotoxicity. Microbial community analysis showed that the biostimulation did not change the dominant species in the original in situ community, and increased the proportion of sulfolane-degraders. The outcome of this study can be used to set parameters for the remediation of groundwater that is contaminated by sulfolane in oil refineries.

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The radioactive contamination has been reported frequently from agricultural lands and ground water. The main reason behind the radioactive pollution is unprotected mining of radioactive elements, unsafe discard of nuclear industrial waste, military applications, dumping of medically used radioisotopes, globally situated (>400) nuclear power plants and use of phosphate fertilizers in farming. Radionuclides are well known potent carcinogens that may cause the various types of cancers to human and animals due to the long exposure to radioactive contaminated sites. To get rid of from the radioactive pollution there is a need of practically successful and cost effective bioremediation technologies that should able to decontaminate the effected lands and water to benefit the mankind. Microbial and phytoremediation are well studied methods for decreasing or gradually eliminating the radioactive contaminants. In this review, we discussed the different strategies of microbial and phytoremediation of radionuclides and recent advancements, that can play the major role in bioremediation of soil and water.

Different remediation technologies based on physical (precipitation, extraction and membrane separation technologies) and chemical (chemical extraction and leaching, hydrolysis, etc.) methods to remediate the radioactive compounds from soils and water are being developed and evaluated. Most of these technologies are cost intensive and only applicable to little contaminated sites. On the other hand phytoremediation and microbial bioremediation are scientifically proven for applying at large scale and economical. Phytoremediation is one of the bioengineering treatments in which terrestrial and aquatic plants have been successfully used for cleaning the radioactive pollutants from diverse environments. Present review article is a updating the recent developments came in the different bioremediation methods. Moreover aim of this manuscript is also emerging the research gaps and identified the future research frontiers to unlock the complexity of phyto and microbial remediation advancements. Although several plants and numerous bacteria and fungi have been identified as the potential radioactive accumulator but their complete mechanism of bioremediation is still unknown. Present article will help the researchers to understand the process of bioremediation of radionuclides in more depths and will aware about the requirements of the coming future.HighlightsPhyto and microbial bioremediation of radioactive elements, possibilities and challenges.Causes of radioactive contamination in soil and water.Nanophytoremediation is an advanced technology of phytoremediation.Drawbacks of phytoremediation.

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Layered double hydroxides (LDH) are the cost-effective and high-efficiency materials for remediation of potentially toxic elements (PTEs) in contaminated soil and groundwater. Herein, the effectiveness and mechanisms of a ternary Ca-Mg-Al LDH (CMAL) for the synergistic remediation of As, Cd, and Pb were investigated in contaminated soils and simulative groundwaters for the first time. The immobilization efficiencies of As, Cd, and Pb in both black soil (BS) and red soil (RS) amended by CMAL at 5 wt% were all > 75%. CMAL amendment transferred more mobile As, Cd, and Pb fractions in soils to immobile species than did Ca-Al LDH and Mg-Al LDH treatments. Furthermore, using a pump-and-treat technology, 82-98% of these 3 PTEs from contaminated groundwater were successfully immobilized in both CMAL treated BS and RS top-soils. Meanwhile, leaching of Ca, Mg, and Al from CMAL was minimal indicating the material was stable. The excellent immobilization performance of CMAL for these PTEs was attributed to the coating of soil microparticles by CMAL nanosheets that allowed complexation of Ca-O-As/Cd or Mg-O-As/Cd/Pb formation, co-precipitation of Ca/Fe-As and Cd(OH)2, and formation of Ca-bridged ternary complex (FeO-Ca-As/Cd). The adverse effect of oppositive pH/Eh-dependence between As and Cd/Pb was overshadowed by these mechanisms and thus allowed As immobilization. Immobilization of As, Cd, and Pb by CMAL amendment was more favorable for RS soil due to its lower reduction potential and more participation of metal-(hydr)oxides for complexation. Overall, the ternary-LDH is a promising synergistic remediation strategy for multi-PTEs contaminated soil and groundwater.

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The presence of trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) in the subsurface can generate a dissolved phase plume in groundwater. This study developed an alkaline activated sodium persulfate (SPS) sustained release oxidation rod (alkaline SPS SR-Rod) for long-term in situ chemical oxidation accelerated treatment of TCE dissolved from TCE DNAPL, by creating a greater concentration gradient at the TCE DNPL boundary. The dissolution of TCE DNAPL (1 mL) in water (280 mL) generated ~700 mg L-1, with a volumetric mass transfer coefficient (kLa) of 0.0187 d-1. The alkaline SPS SR-Rod system had a kLa of 0.013 d-1 for TCE dissolution at early stage, and thereafter aqueous TCE concentration remained below ~10 mg L-1 over 60 d of reaction. An SPS SR-Rod life-span of 186 d, for 90% of SPS released from the rod, was estimated. In the soil-water system, aqueous TCE was maintained < 3 mg L- 1 throughout the reaction and the soil oxidant demand was determined to be ~4 g-SPS/kg-soil in the alkaline SPS SR-Rod system. These results revealed that the use of the alkaline SPS SR-Rod can be effective as a method of treating dissolved TCE released from DNAPL contamination, and thereby accelerating TCE DNAPL removal.

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Rapid detection methods are needed to investigate the environmental quality risk of soil and groundwater in contaminated lands. Currently there is lack of rapid detection methods to sensitively and accurately analyze contaminations of hexavalent chromium in soil due to the challenge of complex sample pretreatment or expensive instrumentation. Here we report a rapid accurate detection platform for quantifying hexavalent chromium in soil and groundwater with ultrasensitivity. The platform consists of a novel sensor of microProbing beads and a portable microscope. Each microProbing bead was a nanoliter reactor to selectively sequestrate Cr (VI) with the enrichment factor up to 150 ×. The microProbing beads presented the signal uniformity of ~97% for the statistical colorimetric imaging analysis. Combined with a miniaturized microscope, the microProbing beads allowed for detecting aqueous Cr (VI) and soluble Cr (VI) in soil within 45 min. The platform achieved high sensitivity with the detection limits of 0.003 ppb for aqueous Cr (VI) and 0.07 ppm for soil Cr (VI). It accurately detected soil and groundwater samples from a chromium contaminated land in Yangtze River Basin of China. The consistency to the laboratory standard methods was achieved with the low cost of ~0.20 US dollar per test. The microProbing imaging platform with the operational simplicity and device portability is highly promising for the field analysis of Cr (VI) in contaminated lands.

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Thermally enhanced bioremediation (TEB), a new concept proposed in recent years, explores the combination of thermal treatment and bioremediation to address the challenges of the low efficiency and long duration of bioremediation. This study presented a comprehensive review regarding the fundamentals of TEB and its applications in soil and groundwater remediation. The temperature effects on the bioremediation of contaminants were systematically reviewed. The thermal effects on the physical, chemical and biological characteristics of soil, and the corresponding changes of contaminants bioavailability and microbial metabolic activities were summarized. Specifically, the increase in temperature within a suitable range can proliferate enzymes enrichment, extracellular polysaccharides and biosurfactants production, and further enhancing bioremediation. Furthermore, a systematic evaluation of TEB applications by utilizing traditional in situ heating technologies, as well as renewable energy (e.g., stored aquifer thermal energy and solar energy), was provided. Additionally, TEB has been applied as a biological polishing technology post thermal treatment, which can be a cost-effective method to address the contaminants rebounds in groundwater remediation. However, there are still various challenges to be addressed in TEB, and future research perspectives to further improve the basic understanding and applications of TEB for the remediation of contaminated soil and groundwater are presented.

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Permanganate is an oxidant usually applied for in situ soil remediation due to its persistence underground. It has already shown great efficiency for dense nonaqueous phase liquid (DNAPL) degradation under batch experiment conditions. In the present study, experimental permanganate oxidation of a DNAPL - coal tar - sampled in the groundwater of a former coking plant was carried out in a glass bead column. Several glass bead columns were spiked with coal tar using the drainage-imbibition method to mimic on-site pollution spread at residual saturation as best as possible. The leaching of organic pollutants was monitored as the columns were flushed by successive sequences: successive injections of hot water, permanganate solution for oxidation, and ambient temperature water, completed by two injections of a tracer before and after oxidation. Sixteen conventional US-EPA PAHs and selected polar PACs were analyzed in the DNAPL remaining in the columns at the end of the experiment and in the particles collected at several steps of the flushing sequences. Permanganate oxidation of the pollutants was rapidly limited by interfacial aging of the DNAPL drops. Moreover, at the applied flow rate chosen to be representative of in situ injections and groundwater velocities, the reaction time was not sufficient to reach high degradation yields but induced the formation and the leaching of oxygenated PACs.

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