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There is a need to study the spatiotemporal distribution of chlorinated solvent releases in groundwater to understand the risk/threat they pose to human health, water quality, and the environment, which then can be used to prioritize clean-up and evaluate regulatory closure with appropriate risk management controls. This paper provides a statistical analysis of spatiotemporal distribution of perchloroethylene (PCE) (and its degradation products including trichloroethene [TCE]) from eighty-three cases across California for which data were available onthe State Water Resources Control Board's GeoTracker database and the Department of Toxic Substance Control Board's Envirostor database. These cases consisted of seventy-one dry cleaning sites and twelve other similar small solvent release sites. Statistical analyses of available groundwater data were performed to estimate: maximum concentrations at the source area, groundwater plume length, plume stability; and correlations between plume length, concentrations, and plume age. At 90% of the sites, the PCE and TCE plume lengths were less than 1,569 feet (478 meters) and 1,782 feet (543 meters), respectively. The average plume lengths for PCE and TCE were 670 feet (204 meters) and 701 feet (213 meters), respectively. At 90% of the sites that have reached stable conditions, PCE and TCE concentrations at the source areas were less than 2,670 and 660 micrograms per liter (µg/L) respectively. This study for the first time provides key characteristics of small chlorinated-solvent plume behaviors in California that can be used to prioritize management of small chlorinated-solvent release sites and to develop strategies towards achieving closure at these sites. [ABSTRACT FROM AUTHOR]

This study explores the use of pine wood biochar (BC) waste gasified at 950 °C as fillers in polymer matrices to create BC@biopolymer composites with perspectives in groundwater remediation. Four biochar samples underwent different sieving and grinding processes and were extensively characterized via UV–Vis, FTIR, and FESEM–EDS, highlighting the fact that that BCs are essentially graphitic in nature with a sponge-like morphology. The grinding process influences the particle size, reducing the specific surface area by about 30% (evaluated by BET). The adsorption performances of raw BC were validated via an adsorption isotherm using trichloroethylene (TCE) as a model contaminant. A selected BC sample was used to produce hydrophilic, stable polymer composites with chitosan (CS), alginate (ALG), potato starch (PST), and sodium carboxymethylcellulose (CMC) via a simple blending approach. Pilot sedimentation tests over 7 days in water identified BC@PST and BC@CMC as the most stable suspensions due to a combination of both hydrogen bonds and physical entrapment, as studied by FTIR. BC@CMC showed optimal distribution and retention properties without clogging in breakthrough tests. The study concludes that biopolymer-based biochar composites with improved stability in aqueous environments hold significant promise for addressing various groundwater pollution challenges. [ABSTRACT FROM AUTHOR]

Biochar (BC) was used to remove trichloroethylene (TCE) from soil and water phases, and BC modification changed the sorption behavior of pollutants. Microplastics are emerging pollutants in the soil and water phases. Whether microplastics can affect the sorption of TCE by modified BC is not clear. Thus, batch sorption kinetics and isotherm experiments were conducted to elucidate the sorption of TCE on BC, and BC combined with polyethylene (PE) or polystyrene (PS). The results showed that HCl and NaOH modification increased TCE sorption on BC, while HNO3 modification inhibited TCE sorption on BC. When PE/PS and BC coexisted, the TCE sorption capacity decreased significantly on BC-CK + PE, BC-HCl + PE, BC-HNO3 + PE, BC-NaOH + PE, and BC-NaOH + PS, which was likely due to the preferential sorption of PE/PS on BC samples. We concluded that microplastics can change TCE sorption behavior and inhibit TCE sorption on BC samples. Thus, the interaction of BC and microplastics should be considered when BC is used for TCE removal in soil and water remediation. HIGHLIGHTS HCl and NaOH modification increased trichloroethylene (TCE) sorption on biochar.; HNO3 modification inhibited TCE sorption on biochar.; Microplastics could change TCE sorption behavior.; Polyethylene/polystyrene could preferentially adsorb onto biochar and inhibit TCE sorption by biochar samples.;

Less attention was paid to the remediation of volatile organic compounds (VOCs) contaminated soil treated by thermal conduction heating (TCH) coupled with chemical oxidization. In this study, the lab-scale remediation experiments of trichloroethylene (TCE)-contaminated soil by TCH and TCH coupled with persulfate (TCH + PS) were performed to explore the influences of PS usage, temperature, reaction time, and the variation of soil properties. TCE was removed from contaminated soils using TCH with a temperature lower than boiling point, and the removal ratio of TCE reached 78.21% with a reaction time of 6h at 60 °C. In the TCH + PS treatments, the removal ratio increased to 87.60~99.50% when the PS dosage was increased from 7.0 mmol/kg to 17.5 mmol/kg at 60 °C. However, the usage efficiency of PS had no positive relationship with oxidant usage and temperature. The treatment with 14 mmol/kg PS after 3h at 50 °C had the highest PS usage ratio of 3.05. In addition, soil pH and soil organic matter (SOM) did not decrease significantly in the TCH-only treatment, while the content of SOM declined by almost 50% after the TCH + PS treatment. Overall, it was concluded that TCH + PS achieved higher removal efficiency, whereas TCH had less disturbance on soil pH and SOM. As such, the applicability of TCH-only or TCH + PS treatments is site-specific. [ABSTRACT FROM AUTHOR]

Abstract Background Advanced understanding of tumor biology has recently revealed the complexity of cancer genetics, intra/inter-tumor heterogeneity, and diverse mechanisms of resistance to cancer treatment. In turn, there has been a growing interest in cancer prevention and minimizing exposure to potential environmental carcinogens that surround us. In the 1980s, several chemical carcinogens, including perchloroethylene (PCE), trichloroethylene (TCE), and benzene, were detected in water systems supplying Camp Lejeune, a US Marine Corps Base Camp located in North Carolina. Case presentation This article presents three cases of cancer patients who have lived at Camp Lejeune, and, decades later, came to our clinic located 1000 miles from the original exposure site. The first patient is a young Caucasian man who was diagnosed with T cell acute lymphoblastic leukemia at the age of 37, and the second patient is a Caucasian man who had multiple types of cancer in the prostate, lung, and colon as well as chronic lymphocytic leukemia in his 60s and 70s. The third patient is another Caucasian man who had recurrent skin cancers of different histology, namely basal cell carcinomas, squamous cell carcinomas, and melanoma, from his 50s to 70s. Conclusions The US Congress passed the Honoring America’s Veterans and Caring for Camp Lejeune Families Act in 2012, which covers appropriate medical care for the people affected by the contamination. We hope that this article raises awareness about the history of Camp Lejeune’s water contamination among cancer care providers, so the affected patients can receive appropriate medical coverage and cancer screening across the country.

Asphalt industries are actively pursuing the integration of recycled asphalt pavement (RAP) into their constructions to promote sustainable pavement solutions amidst resource scarcity. However, challenges persist in the extraction and recovery processes, potentially affecting asphalt pavement performance assessments. This study investigates the impact of three common solvents—n-propyl bromide (nPB), trichloroethylene (TCE), and a toluene-ethanol blend (85 %/15 %)—on the rheological properties of recovered binders, particularly aiming to identify a substitute for TCE in light of its proposed ban by the Environmental Protection Agency (EPA) in the USA. Tests were conducted on six different performance-graded (PG) binders from diverse sources, assessing high-temperature properties using Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests, as well as low-temperature properties via Bending Beam Rheometer (BBR). Fourier Transform Infrared (FTIR) spectroscopy confirmed the absence of solvents in the recovered binders. Although minor variations were observed in measured properties between original and recovered binders due to solvent use, these differences did not affect the resulting performance grades. Thus, the toluene-ethanol blend can potentially substitute for TCE. However, it is noteworthy that the toluene-ethanol blend (85 %/15 %) displayed a slower solubility rate compared to nPB and TCE, underscoring the need for caution in its usage. • TCE, nPB, and Toluene didn't impact the resulting performance grade of the recovered asphalt binder. • Toluene exhibited lower solubility in the asphalt binder. • Rheological tests (DSR and MSCR) evaluate the rheological properties of the recovered binder. • FTIR detects the solvent in recovered binders. • Environmental Protection Agency (EPA) proposed a ban on TCE in the USA. [ABSTRACT FROM AUTHOR]

Background: Advanced understanding of tumor biology has recently revealed the complexity of cancer genetics, intra/inter-tumor heterogeneity, and diverse mechanisms of resistance to cancer treatment. In turn, there has been a growing interest in cancer prevention and minimizing exposure to potential environmental carcinogens that surround us. In the 1980s, several chemical carcinogens, including perchloroethylene (PCE), trichloroethylene (TCE), and benzene, were detected in water systems supplying Camp Lejeune, a US Marine Corps Base Camp located in North Carolina.Case Presentation: This article presents three cases of cancer patients who have lived at Camp Lejeune, and, decades later, came to our clinic located 1000 miles from the original exposure site. The first patient is a young Caucasian man who was diagnosed with T cell acute lymphoblastic leukemia at the age of 37, and the second patient is a Caucasian man who had multiple types of cancer in the prostate, lung, and colon as well as chronic lymphocytic leukemia in his 60s and 70s. The third patient is another Caucasian man who had recurrent skin cancers of different histology, namely basal cell carcinomas, squamous cell carcinomas, and melanoma, from his 50s to 70s.Conclusions: The US Congress passed the Honoring America's Veterans and Caring for Camp Lejeune Families Act in 2012, which covers appropriate medical care for the people affected by the contamination. We hope that this article raises awareness about the history of Camp Lejeune's water contamination among cancer care providers, so the affected patients can receive appropriate medical coverage and cancer screening across the country. [ABSTRACT FROM AUTHOR]

Residential and occupational exposures to the industrial solvents perchloroethylene (PERC) and trichloroethylene (TCE) present public health concerns. In humans, maternal PERC and TCE exposures can be associated with adverse birth outcomes. Because PERC and TCE are biotransformed to toxic metabolites and placental dysfunction can contribute to adverse birth outcomes, the present study compared the toxicity of key PERC and TCE metabolites in three in vitro human placenta models. We measured cell viability and caspase 3 + 7 activity in the HTR-8/SVneo and BeWo cell lines, and caspase 3 + 7 activity in first trimester villous explant cultures. Cultures were exposed for 24 h to 5–100 µM S -(1,2-dichlorovinyl)- L -cysteine (DCVC) and S -(1,2,2-trichlorovinyl)- L -cysteine (TCVC), or 5–200 µM trichloroacetate (TCA) and dichloroacetate (DCA). DCVC significantly reduced cell viability and increased caspase 3 + 7 activity in HTR-8/SVneo cells at a lower concentration (20 µM) compared with concentrations toxic to BeWo cells and villous explants. Similarly, TCVC reduced cell viability and increased caspase 3 + 7 activity in HTR-8/SVneo cells but not in BeWo cells. TCA and DCA had only negligible effects on HTR-8/SVneo or BeWo cells. This study advances understanding of potential risks of PERC and TCE exposure during pregnancy by identifying metabolites toxic in placental cells and tissues. [Display omitted] • DCVC (20 µM) reduced viability and elevated caspase 3 + 7 activity in HTR-8/SVneo cells. • DCVC (50 µM) reduced viability and elevated caspase 3 + 7 activity in BeWo cells. • DCVC (50 µM) elevated caspase 3 + 7 activity in placental villous explants. • TCVC (50 µM) reduced viability and elevated caspase 3 + 7 activity in HTR-8/SVneo cells. • TCA and DCA had only negligible effects on HTR-8/SVneo and BeWo cells. [ABSTRACT FROM AUTHOR]

The remediation of sites contaminated with chlorinated hydrocarbons (CHCs) poses a challenge, especially in built up areas. Nanoscale zero-valent iron (nZVI) can reduce CHCs to nontoxic compounds. Jet grouting and deep soil mixing is used to overcome the difficulty of homogeneous distribution of nZVI in heterogeneous soils. Because these techniques facilitate a synergistic contaminant treatment and installation of construction elements, it is important to know the reactive interactions among involved compounds. In this study six binder materials [bentonite and ordinary portland cement (OPC), among others] have been investigated for interactions with the reductive dechlorination of trichloroethylene (TCE) by nZVI. The installation process was simulated in batch experiments, and the reaction products (CHC, intermediate products, and hydrogen) were observed using headspace gas chromatography. None of the binders inhibited dechlorination of TCE compared to a control experiment, and the two clay materials even catalyzed the reaction by a factor of up to 12.9. Hydrogen evolution was determined as a sensible indicator for the suitability of a particular binder, ranging from 12.8 to 4,400 mmol. [ABSTRACT FROM AUTHOR]

Groundwater at trichloroethylene (TCE)-contaminated sites lacks electron donors, which prolongs TCE's natural attenuation process and delays treatment. Although adding electron donors, such as emulsified oil, accelerates TCE degradation, it also causes the accumulation of hazardous metabolites such as dichloroethylene (DCE) and vinyl chloride (VC). This study combined in situ chemical reduction using organo-iron compounds with enhanced in situ bioremediation using emulsified oil to accelerate TCE removal and minimize the accumulation of DCE and VC in groundwater. A self-made soybean oil emulsion (SOE) was used as the electron donor and was added to liquid ferrous lactate (FL), the chemical reductant. The combined in situ chemical reduction and enhanced in situ bioremediation achieved favorable results in a laboratory microcosm test and in an in situ biological field pilot test. Both tests revealed that SOE+FL accelerated TCE degradation and minimized the accumulation of DCE and VC to a greater extent than SOE alone after 160 days of observation. When FL was added in the microcosm test, the pH value decreased from 6.0 to 5.5; however, during the in situ biological pilot test, the on-site groundwater pH value did not exhibit obvious changes. Given the geology of the in situ pilot test site, the SOE+FL solution that was injected underground continued to be released for at least 90 days, suggesting that the solution's radius of influence was at least 5 m. [ABSTRACT FROM AUTHOR]

Exposure to the industrial solvent trichloroethylene (TCE) has been associated with adverse pregnancy outcomes in humans and decreased fetal weight in rats. TCE kidney toxicity can occur through formation of reactive metabolites via its glutathione (GSH) conjugation metabolic pathway, largely unstudied in the context of pregnancy. To investigate the contribution of the GSH conjugation pathway and oxidative stress to TCE toxicity during pregnancy, we exposed rats orally to 480 mg TCE/kg/day from gestational day (GD) 6 to GD 16 with and without N-acetyl-l-cysteine (NAC) at 200 mg/kg/day or aminooxyacetic acid (AOAA) at 20 mg/kg/day as pre/co-treatments from GD 5–16. NAC is a reactive oxygen species scavenger that modifies the GSH conjugation pathway, and AOAA is an inhibitor of cysteine conjugate β-lyase (CCBL) in the GSH conjugation pathway. TCE decreased fetal weight, and this was prevented by AOAA but not NAC pre/co-treatment to TCE. Although AOAA inhibited CCBL activity in maternal kidney, it did not inhibit CCBL activity in maternal liver and placenta, suggesting that AOAA prevention of TCE-induced decreased fetal weight was due to CCBL activity inhibition in the kidneys but not liver or placenta. Unexpectedly, NAC pre/co-treatment with TCE, relative to TCE treatment alone, altered placental morphology consistent with delayed developmental phenotype. Immunohistochemical staining revealed that the decidua basale, relative to basal and labyrinth zones, expressed the highest abundance of CCBL1, flavin-containing monooxygenase 3, and cleaved caspase-3. Together, the findings show the differential effects of NAC and AOAA on TCE-induced pregnancy outcomes are likely attributable to TCE metabolism modulation. [ABSTRACT FROM AUTHOR]

In addition to providing a physical compartment for gestation, the fetal membranes (FM) are an active immunological barrier that provides defense against pathogenic microorganisms that ascend the gravid reproductive tract. Pathogenic infection of the gestational tissues (FM and placenta) is a leading known cause of preterm birth (PTB). Some environmental toxicants decrease the capacity for organisms to mount an immune defense against pathogens. For example, the immunosuppressive effects of the widespread environmental contaminant trichloroethylene (TCE) are documented for lung infection with Streptococcus zooepidemicus. Group B Streptococcus (GBS; Streptococcus agalactiae) is a bacterial pathogen that is frequently found in the female reproductive tract and can colonize the FM in pregnant women. Work in our laboratory has demonstrated that a bioactive TCE metabolite, S-(1, 2-dichlorovinyl)-L-cysteine (DCVC), potently inhibits innate immune responses to GBS in human FM in culture. Despite these provocative findings, little is known about how DCVC and other toxicants modify the risk for pathogenic infection of FM. Infection of the gestational tissues (FM and placenta) is a leading known cause of PTB, therefore toxicant compromise of FM ability to fight off infectious microorganisms could significantly contribute to PTB risk. This Perspective provides the current status of understanding of toxicant-pathogen interactions in FM, highlighting knowledge gaps, challenges, and opportunities for research that can advance protections for maternal and fetal health.

As one of the remediation reagents, potassium permanganate (KMnO4) is injected to the aquifer, degrading trichloroethylene (TCE) by chemical oxidation. This study investigated the kinetics of TCE degradation by series of batch experiments, as well as the influence of medium size. Moreover, phase-transfer catalyst (PTCs), such as pentyltriphenylphosphonium bromide (PTPP) and sodium hexametaphosphate (SHMP) were used for enhancing oxidation. The batch experimental results showed that in the absence of PTC, the removal efficiency of TCE was 36.14% and 86.79% within 4 and 30 min, respectively. However, the removal rate of TCE was up to 67.48% and 49.90% within 4 min for 15 mol% PTPP- and SHMP-added system, respectively. The results indicated that PTPP and SHMP promoted the depletion of M n O 4 − to oxidize DNAPL TCE, but its effectiveness varied with the addition ratio of PTPP or SHMP. Its promotion was more remarkable when PTC added with a higher proportion. The alleviation of MnO2 by phosphates ( P O 4 3 − , H P O 4 2 − and H 2 P O 4 − ) or PTC in the presence of media was qualitatively investigated. Results showed that the content of MnO2 in the dissolved phase during the same reaction period decreased by PTC. Moreover, H P O 4 2 − and SHMP have apparent beneficial effects of reducing MnO2 formation. The presence of aquifer media has a pH buffer and a negative influence on the reaction between TCE and the oxidant; moreover, as particle size of media decreased, the negative effect increased. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE) is the most ubiquitous halogenated organic pollutant in the environment, it is one of the 129 priority control pollutants. In order to clarify the influence of TCE on microorganisms and nitrogen transformation in Mollisol is the core purpose of this study. Results showed that 10 mg kg−1 TCE is the concentration limit of ammonification in Mollisol. When the concentration of TCE reached 10 mg kg−1 and the effect lasted for over 7 days, the process of ammonia oxidation to nitric acid in Mollisol will be affected. TCE affected the process of nitrate (NO3−) transformation into nitrite (NO2−) by affecting the activity of nitrate reductase, thereby affected the denitrification process in soil. When the concentration of TCE is more than 10 mg kg−1 it reduced the ability of soil microorganisms to obtain nitrogen, thereby affecting soil nitrogen transformation. RDA (Redundancy analysis) showed that the activity of nitrate reductase and the number of nitrifying bacteria and denitrifying bacteria in soil was negatively correlated with the incubation of TCE. In addition, soil nitrate reductase, nitrite reductase, peroxidase activity, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria were negatively correlated with TCE concentration. Beyond that PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) of functional gene structure depend on KEGG (Kyoto Encyclopedia of Genes and Genomes) showed that 20 mg kg−1 TCE significantly inhibited the metabolism of energy and other substances in Mollisol. Based on the above, it is found that TCE significantly affected nitrification and denitrification in Mollisol, thus the nitrogen transformation in Mollisol was affected by TCE contamination. Highlights: 10 mg kg−1 TCE is the concentration limit of ammonification in Mollisol. TCE significantly affected nitrification and denitrification in Mollisol. Enzymes and bacteria related to nitrogen transformation are negatively correlated with TCE concentration. 20 mg kg−1 TCE inhibited the abundance of Amino Acid Metabolism genes and Energy Metabolism genes. Nitrogen transformation and microbial community structure in Mollisol was affected by TCE contamination. [ABSTRACT FROM AUTHOR]

In addition to providing a physical compartment for gestation, the fetal membranes (FM) are an active immunological barrier that provides defense against pathogenic microorganisms that ascend the gravid reproductive tract. Pathogenic infection of the gestational tissues (FM and placenta) is a leading known cause of preterm birth (PTB). Some environmental toxicants decrease the capacity for organisms to mount an immune defense against pathogens. For example, the immunosuppressive effects of the widespread environmental contaminant trichloroethylene (TCE) are documented for lung infection with Streptococcus zooepidemicus. Group B Streptococcus (GBS; Streptococcus agalactiae) is a bacterial pathogen that is frequently found in the female reproductive tract and can colonize the FM in pregnant women. Work in our laboratory has demonstrated that a bioactive TCE metabolite, S-(1, 2-dichlorovinyl)-L-cysteine (DCVC), potently inhibits innate immune responses to GBS in human FM in culture. Despite these provocative findings, little is known about how DCVC and other toxicants modify the risk for pathogenic infection of FM. Infection of the gestational tissues (FM and placenta) is a leading known cause of PTB, therefore toxicant compromise of FM ability to fight off infectious microorganisms could significantly contribute to PTB risk. This Perspective provides the current status of understanding of toxicant-pathogen interactions in FM, highlighting knowledge gaps, challenges, and opportunities for research that can advance protections for maternal and fetal health. [ABSTRACT FROM AUTHOR]

Groundwater at trichloroethylene (TCE)-contaminated sites lacks electron donors, which prolongs TCE’s natural attenuation process and delays treatment. Although adding electron donors, such as emulsified oil, accelerates TCE degradation, it also causes the accumulation of hazardous metabolites such as dichloroethylene (DCE) and vinyl chloride (VC). This study combined in situ chemical reduction using organo-iron compounds with enhanced in situ bioremediation using emulsified oil to accelerate TCE removal and minimize the accumulation of DCE and VC in groundwater. A self-made soybean oil emulsion (SOE) was used as the electron donor and was added to liquid ferrous lactate (FL), the chemical reductant. The combined in situ chemical reduction and enhanced in situ bioremediation achieved favorable results in a laboratory microcosm test and in an in situ biological field pilot test. Both tests revealed that SOE+FL accelerated TCE degradation and minimized the accumulation of DCE and VC to a greater extent than SOE alone after 160 days of observation. When FL was added in the microcosm test, the pH value decreased from 6.0 to 5.5; however, during the in situ biological pilot test, the on-site groundwater pH value did not exhibit obvious changes. Given the geology of the in situ pilot test site, the SOE+FL solution that was injected underground continued to be released for at least 90 days, suggesting that the solution’s radius of influence was at least 5 m.

Sulfide-modified nanoscale zero-valent iron (S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles (NPs) easily agglomerate and have poor contact with organic contaminants. Herein, we propose a new S-nZVI/graphene aerogel (S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene (TCE) from water. Three-dimensional porous graphene aerogel (GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs. The TCE removal rates of FeS, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively. Furthermore, TCE was completely removed within 50 min by S-nZVI/GA. The TCE removal rate increased with increasing pH and temperature, and TCE removal followed the pseudo-first-order kinetic model. The results demonstrate the great potential of S-nZVI/GA composite as a low-cost, easily separated and superior monolithic adsorbent for removal of organic pollutants. Unlabelled Image [ABSTRACT FROM AUTHOR]

Dispersants including Tween 20, Tween 40, Tween 60, and polyacrylic acid (PAA) were used to modify nanoscale zero-valent iron (nZVI). All dispersants dispersed nZVI effectively. PAA-modified nZVI was more stable than nZVI that was modified with Tween surfactant. Iron nanoparticles that were prepared using 0.5–5.0% (vol%) of PAA remained in suspension for more than 2 h. nZVI that was modified using Tween surfactant remained in suspension for 30–60 min, and there was complete sedimentation of bare iron in 10 min. When 2.0–5.0% (vol%) of Tween surfactant was used, the stability of the nZVI that was modified using Tween 20 was much better than that for nZVI that was modified using Tween 40 or Tween 60. The results for the transportation test show that nZVI that was prepared using 2% (vol%) of Tween 20 exhibited the best mobility in porous media. Approximately 83–90% of TCE was degraded by bare, PAA-modified, and Tween 20-modified nZVI, and about 63–67% of TCE was removed by nZVI that was modified using Tween 40 and Tween 60 during 20 days of reaction. The production of cis-dichloroethene (DCE) and 1,1-DCE demonstrates that TCE is removed via reductive dechlorination. The results of this study show that PAA- and Tween 20-modified nZVI are more practical for in situ remediation because they exhibit good mobility and degrade TCE effectively. [ABSTRACT FROM AUTHOR]

• nCaO 2 performed better for TCE degradation than conventional CaO 2. • Citric acid significantly enhanced TCE degradation. • HO was the primary ROSs in CaO 2 /Fe(II) and CaO 2 /Fe(II)–CA systems. • Cl− and HCO 3 − inhibited TCE degradation at different levels. • Effective degradation of TCE in actual groundwater was achieved. In this study, nCaO 2 was synthesized successfully and applied in the Fe(II)-based catalytic environments in investigating trichloroethylene (TCE) removal performance. nCaO 2 with the particle sizes in the range of 50–200 nm was prepared, and it performed better for TCE removal when compared to the conventional CaO 2. Further experimental results showed that 70.4% of TCE could be removed in 180 min at the nCaO 2 /Fe(II)/TCE molar ratio of 1/2/1, while this data was elevated to 86.1% in the presence of citric acid (CA) at the nCaO 2 /Fe(II)/CA/TCE molar ratio of 1/2/2/1 in the same test period. Probe compound tests, specifically designed for free radicals confirmation, demonstrated the presence of HO and O 2 − . Moreover, scavenging tests indicated that HO was the major radical responsible for TCE degradation but O 2 − promoted the removal of TCE in both nCaO 2 /Fe(II) and nCaO 2 /Fe(II)-CA system. In addition, the effects of initial solution pH and anions (Cl−, HCO 3 −) were also evaluated. The performance of TCE degradation in actual groundwater demonstrated that both nCaO 2 /Fe(II) and nCaO 2 /Fe(II)-CA systems can be applicable for TCE removal in ISCO practice and the nCaO 2 /Fe(II)-CA system is much promising technique. These fundamental data strongly confirmed the feasibility and potential of nCaO 2 based technique in the remediation of TCE contaminated groundwater. [ABSTRACT FROM AUTHOR]

The objectives of this research are to investigate the effect of solvent in asphalt binder, and to propose a method to determine the actual performance of asphalt binder extracted from asphalt mixture thus improving the efficiency of using RAP. The Fourier-transform infrared spectroscopy (FTIR) test was used to analyze the functional groups of trichloroethylene (TCE) and asphalt binder with TCE. This test also qualitatively and quantitatively evaluated the influence of solvent in asphalt binder. Dynamic Shear Rheometer (DSR) test was employed to measure the complex shear modulus (|G∗|) of asphalt binder with different TCE contents and to establish the relationship between the TCE contents and the |G∗| of asphalt binder. Based on the testing results, functional group = C–H of TCE can be used as an indicator to verify the existence of TCE in the extracted asphalt binder. Both band areas 834-848 cm-1 and 918-938 cm-1 changed for PG 58–28 and Pressure Aging Vessel (PAV) aged PG 58-28 binder after the addition of TCE. Band area 918-938 cm-1 can better reflect the influence of TCE in asphalt binder. Band area 834-848 cm-1 did not change when TCE content was at a low level. Both the existence of TCE and the content of TCE had a significant influence on the |G*| of unaged and PAV aged PG 58–28 asphalt binder. A regression function was built to establish the relationship between the TCE content and |G*|. With the method developed in this study, the correlation between the TCE amount and the FTIR spectrum area was quantified. The actual |G∗| of asphalt binder without TCE can be back calculated. The method used in this study provided guidance for the determination of asphalt binder performance extracted from RAP, which can be beneficial to the design of asphalt mixtures with RAP. [ABSTRACT FROM AUTHOR]

Trichloroethylene, a chlorinated solvent widely used as a degreasing agent, is a common environmental contaminant. Emerging evidence suggests that chronic exposure to trichloroethylene (TCE) contributes to the development of Parkinson's disease (PD). TCE induced LRRK2 kinase activity in the rat brain and produced a significant dopaminergic lesion in the nigrostriatal tract with elevated oxidative stress. Here we have utilized TCE-induced PD model for the assessment of test drug. Oral gavage administration of TCE at a dose of 1000 mg/kg/day for 6 weeks was utilized to induced PD. Muscle grip strength was estimated by rotarod and grid performance test. Motor activity by actophotometer and locomotor stability were assessed by forelimb locomotor scale (FLS) and forelimb step alternation test (FSAT). However, the postural stability was assessed by postural stability test (PST). Biochemical estimation consists of determination of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), GSH level (reduced glutathione), and nitrite concentration., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

A novel hybrid system constituting of La–Mn-based perovskite-type catalyst with nonthermal plasma (NTP) is developed and evaluated for the removal of trichloroethylene (TCE) from gas streams. Ce and Ni were used as promoter for modification LaMnO3 because addition of Ce and Ni could enhance redox property and activity of catalyst. First, the activities of various perovskites including LaMnO3, La0.8Ce0.2MnO3, and La0.8Ce0.2Mn0.8Ni0.2O3 were evaluated for TCE removal via catalysis, and the results indicate that La0.8Ce0.2Mn0.8Ni0.2O3 has the highest activity for TCE removal among three perovskites prepared. The three perovskites are individually combined with NTP to form various plasma catalysis systems for TCE removal. Experimental results indicate that 100% TCE removal efficiency can be achieved with plasma catalysis (La0.8Ce0.2Mn0.8Ni0.2O3) when the system is operated with the applied voltage of 16 or 17 kV. On the other hand, the highest TCE removal efficiency achieved with NTP alone is 73.2% with the applied voltage of 17 kV. In addition, CO2 mineralization efficiencies achieved with plasma catalysis combined with La0.8Ce0.2Mn0.8Ni0.2O3 (31.1%–46.6%) are significantly higher than that of NTP alone (8.4%–13.1%). It is worth noting that concentrations of O3 and NOx generated with plasma catalysis are significantly lower than that of NTP alone, implying that formation of O3 and NOx could be effectively decomposed as plasma catalysis is applied for TCE removal. Overall, perovskite-type catalyst can be integrated with NTP to form plasma catalysis system for effective removal of TCE from gas streams. [ABSTRACT FROM AUTHOR]

Three perovskite-type catalysts including LaMnO3, La0.8Ce0.2MnO3, and La0.8Ce0.2 Mn0.8Ni0.2O3 are prepared using citric acid sol-gel method and evaluated as catalyst for the oxidation of trichloroethylene (TCE) in air with temperature ranging from 100 to 600 °C. The physicochemical properties of three perovskite-type catalysts were characterized by SEM, EDS, XRD, BET, and XPS to investigate the relationship with catalytic activities. The results show that the removal efficiency of TCE achieved with La0.8Ce0.2Mn0.8Ni0.2O3 (the best one) reaches 100% at 400 °C and the mineralization efficiency reaches 100% at 600 °C. The enhanced activity can be attributed to the addition of Ce and Ni which increases the surface areas, active oxygen species, and the redox ability of the Mn4+/Mn3+ ratio on the catalyst surface. As La0.8Ce0.2Mn0.8Ni0.2O3 is applied for TCE oxidation, the main intermediate chlorinated byproduct detected is tetrachloroethylene (C2Cl4) which is generated by the reaction of TCE and chlorine (Cl2). The activation energy for the TCE oxidation with La0.8Ce0.2Mn0.8Ni0.2O3 catalyst is 51 kJ/mol using kinetic models of power-law type. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE) commonly exists in contaminated water as a persistent toxic pollutant. The advanced oxidation of persulfate (PS) is a promising method for degrading organic pollutants. Heterogeneous Fe-carbon composites prepared by pyrolysis with metal–organic frameworks (MOFs) have attracted attention. However, the intrinsic relationship between the physicochemical properties and catalytic performance of MOF-derived carbon compounds via PS is unclear. This study investigates TCE removal by Fe-MOF-derived carbon (MFC) with PS. The effects of the precursor template structure, pyrolysis temperature, and coexisting substances on TCE removal over the MFC/PS system are examined. Fe-MOF-derived from different precursor templates presented different TCE removal rates of 75.2–85.0%. The pyrolysis temperature of MFC alters the pore size, phase composition, and other properties, thereby affecting electron transport in the materials and catalyzing the degradation process. The total TCE removal reached 85.8% with MFC600, derived from MF88B and pyrolyzed at 600 ℃. This catalyst demonstrated excellent performance for PS degradation over a wide pH range (3−9). Moreover, free-radical and nonradical pathways coexist in the MFC600/PS system. During the TCE degradation process, oxygen vacancies, Fe species (Fe0, Fe 3 N, Fe 3 C, and Fe 3 O 4), and N species (pyridinic N and graphitic N) were active centers in the material and played a major role in catalytic degradation. They participated in the subsequent generation of HO•, SO 4 •-, and •O 2 -, and 1O 2. Furthermore, a possible degradation mechanism is proposed. This study elucidates the control of the physicochemical properties of carbon-based catalysts by exploiting MOF diversity. [Display omitted] • TCE removal (75.2–85.0%) varied with Fe-MOF-derived carbon types. • MF88B-derived carbon pyrolyzed at 600 ℃ gave a TCE removal of 85.8%. • Oxygen vacancies, Fe species, and N species were the catalytic active sites for PS. • Radical and non-radical processes coexist in MFC600/persulfate system. • MFC600 exhibits an excellent catalytic performance for a wide pH range. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO) is a promising support for electrochemical and environmental applications. However, the role of rGO in dechlorination of chlorinated hydrocarbon by zerovalent iron-based nanoparticles remains unclear. Herein, the rGO-supported bimetallic Fe/Ni nanocomposites were fabricated by chemical reduction method and the microstructures as well as the electrochemical properties of rGO/Fe/Ni, were investigated to elucidate the dechlorination behaviors of trichloroethylene (TCE) under various environmental conditions. Results show that the 10–60 nm Fe/Ni nanoparticles with average particle size of 32 nm are homogeneously dispersed onto the rGO surface. The rGO/Fe/Ni exhibits excellent dechlorination efficiency and rate of TCE is 2.4 times higher than that of free Fe/Ni nanoparticles. Cyclic voltammetric curves and electrochemical impedance spectra indicate that the superior dechlorination activity is attributed to the strong interaction between Fe/Ni and rGO, low internal resistance and rapid diffusion rate of electrons and ions. In addition, the capacitive behavior of rGO can store and transfer 2.7–3.4 electrons produced from Fe 0 to the adsorbed TCE more readily, and then converts TCE to non-toxic ethane via hydrodechlorination in the presence of Ni nanoparticles. The rGO/Fe/Ni can be recycled for at least 8 times to effective dechlorinate TCE. Moreover, the reaction rate of TCE dechlorination can be enhanced 1.26–1.49 times when 5–10 mg L −1 humic acid are added. Results obtained in this study have clearly unveiled the role of rGO in hydrodechlorination of TCE and can provide a new insight into the development of rGO−supported bimetallic Fe/Ni nanoparticles for the enhanced removal of chlorinated pollutants in water and wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, factors that influenced the process of trichloroethylene (TCE) degradation using the sulfite/UV-L Advanced Reduction Process (ARP) were analyzed, as well as the interrelation of these factors, the correlation between factors, and the trichloroethylene (TCE) degradation efficiency. Four factors were evaluated: pH, reductive reagent (sulfite) concentration, UV254 intensity, and trichloroethylene (TCE) concentration. The efficiency of trichloroethylene (TCE) degradation by the sulfite/UV-L Advanced Reduction Process (ARP) increased as the initial pH increased. Considering economy, pH 10 was decided as the optimum condition. The trichloroethylene (TCE) degradation efficiency by sulfite/UV-L Advanced Reduction Process (ARP) also increased with increasing sulfite concentration. According to the experimental results, the optimum sulfite concentration to treat 10 mM of the trichloroethylene (TCE) was 10 mg/L. The degradation efficiency of the trichloroethylene (TCE) also increased as the intensity of UV254 radiation was increased. Higher initial concentrations of trichloroethylene (TCE) resulted in decreased degradation efficiency. All the factors also been analyzed using multiple regression carried out by the program SPSS (ver. 22). The pH seemed to have a high correlation with looking pearson coefficient. It is most important to consider the influence of pH when using sulfite/UVL Advanced Reduction Process (ARP). The initial concentration of trichloroethylene (TCE) seemed to have the most relevance by looking pearson coefficient, followed by pH and UV254. The regression model seemed to be appropriate, having a value (0.000), which was much lower than the significance level (0.05), and the correlation coefficient (R2) of 0.816 describes the power elimination rate of trichloroethylene (TCE). [ABSTRACT FROM AUTHOR]

BACKGROUND Zero valent iron (ZVI) has been extensively applied in the remediation of groundwater and wastewater contamination. This study aimed to investigate the depassivation effect of iron-reducing bacterium Shewanella putrefaciens on aged ZVI towards the dechlorination of trichloroethylene in aqueous solutions. RESULTS Both mmZVI and nZVI showed high reactivity towards TCE until they were passivated. Lepidocrocite was identified as the main corrosion product of nZVI, while green rust was identified as the main corrosion product of mmZVI. More importantly, the combination of iron-reducing bacteria with aged mmZVI generated greater enhancement of TCE removal than the combination with nZVI. Better bacterium-mineral association conditions determined by SEM and the release of ZVI in the core of aged mmZVI counted for the depassivation effect of iron-reducing bacterium on aged mmZVI. Moreover, dialysis bag experiments indicated that Shewanella putrefaciens could employ both indirect and direct mechanisms of electron transfer to iron oxide, and the addition of metal chelating agent promoted the iron reducing process greatly. Synergistic mechanisms between dissimilatory iron reducing bacteria (DIRB) and aged ZVI was proposed. CONCLUSION This study demonstrated that the contaminants reduction ability of aged ZVI could be recovered to some extent by DIRB and DIRB influenced the long-term performance of ZVI. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The present study investigated the degradation of trichloroethylene (TCE) in sand suspensions by Fenton-like reaction with magnetite (FeO) in the presence of various chelators at circumneutral pH. The results showed that ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) greatly improved the rate of TCE degradation, while [S,S]-ethylenediaminedisuccinic acid (s,s-EDDS), malonate, citrate, and phytic acid (IP6) have minimal effects on TCE degradation. Quenching tests suggested that TCE was mainly degraded by hydroxyl radical (HO) attack, with about 90% inhibition on TCE degradation by the addition of HO scavenger 2-propanol. The presence of 0.1-0.5% FeO/sand ( w/ w) contributed to 40% increase in TCE degradation rates. In particular, the use of chelators can avoid high concentrations of HO required for the Fenton-like reaction with FeO, and moreover improve the stoichiometric efficiencies of TCE degradation to HO consumption. The suitable concentrations of chelators (EDTA and NTA) and HO were suggested to be 0.5 and 20 mM, respectively. Under the given conditions, degradation rate constants of TCE were obtained at 0.360 h with EDTA and 0.526 h with NTA, respectively. Enhanced degradation of TCE and decreased usage of HO in this investigation suggested that Fenton-like reaction of FeO together with NTA (or EDTA) may be a promising process for remediation of TCE-contaminated groundwater. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE), commonly used as an industrial solvent, is ubiquitous in our living environment. TCE exposure can induce hepatocellular carcinoma (HCC) in mice, but the underlying mechanisms remain elusive. To understand the role of miRNA in the hepatocarcinogenesis of TCE, we examined the miRNA expression profiles by microarray in the liver of B6C3F1 male mice exposed to TCE at 0 or 1000 mg/kg b.w. Nine differentially expressed miRNAs were identified, out of which miR-182-5p exhibited the highest increase in expression. Moreover, the TCE-induced upregulation of miR182-5p in mouse liver was dose dependent and correlated with promoter DNA hypomethylation. Treatment of mouse liver cell lines (BNL CL.2 and Hepa1-6) with TCE at non-toxic doses (0.1 and/or 0.3mM) significantly increased the expression level of miR-182-5p accompanied with elevated cell proliferation. The TCE-induced cell proliferation was further found to be mediated by miR-182-5p overexpression. Additionally, tumor suppressor gene Cited2, which was downregulated in TCE exposed mouse liver cells, was proved to be a direct target of miR-182-5p. In conclusion, TCE might up-regulate miR-182-5p expression by DNA hypomethylation, which could suppress Cited2 and improve cell proliferation rate, resulting in liver tumor. [ABSTRACT FROM AUTHOR]

Groundwater contamination by chlorinated solvents causes potential threats to water resources and human health. Therefore, it is important to develop effective technologies to remediate contaminated groundwater. This study uses biodegradable hydrophilic polymers, hydroxypropyl methylcellulose (HPMC), hydroxyethyl cellulose (HEC) and polyvinyl pyrrolidone (PVP) as binders to manufacture persulfate (PS) tablets for the sustained release of persulfate to treat trichloroethylene (TCE) in groundwater. The release time for different tablets decreases in the order: HPMC (8–15 days) > HEC (7–8 days) > PVP (2–5 days). The efficiency with which persulfate is released is: HPMC (73–79%) > HEC (60–72%) > PVP (12–31%). HPMC is the optimal binder for the manufacture of persulfate tablets and persulfate is released from a tablet of HPMC/PS ratio (wt/wt) of 4/3 for 15 days at a release rate of 1127 mg/day. HPMC/PS/biochar (BC) ratios (wt/wt/wt) between 1/1/0.02 and 1/1/0.0333 are suitable for PS/BC tablets. PS/BC tablets release persulfate for 9–11 days at release rates of 1243 to 1073 mg/day. The addition of too much biochar weakens the structure of the tablets, which results in a rapid release of persulfate. TCE is oxidized by a PS tablet with an efficiency of 85% and a PS/BC tablet eliminates more TCE, with a removal efficiency of 100%, due to oxidation and adsorption during the 15 days of reaction. Oxidation is the predominant mechanism for TCE elimination by a PS/BC tablet. The adsorption of TCE by BC fits well with the pseudo-second-order kinetics and the pseudo-first-order kinetics, which describes the removal of TCE by PS and PS/BC tablets. The results of this study show that a PS/BC tablet can be used in a permeable reactive barrier for long-term passive remediation of groundwater. [Display omitted] • HPMC is an optimal binder for PS tablet manufacturing. • A PS tablet releases persulfate for 15 days at a release rate of 1127 mg/day. • A PS/BC tablet releases persulfate for 11 days at a release rate of 1073 mg/day. • The amount of BC in a PS tablet is controlled to prevent weakness in the tablet. • TCE removal is increased by using a PS/BC tablet due to adsorption and oxidation. [ABSTRACT FROM AUTHOR]

Zeolite supported nano zero valent iron copper bimetallic composite (Z-nZVFe-Cu) was synthesized using an ion exchange method. The morphology and physico-chemical properties of the Z-nZVFe-Cu composite were determined using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), energy dispersive X-ray spectra (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). The results showed that iron and copper nano particles were well dispersed on the zeolite sheet. The degradation efficiency of trichloroethylene (TCE) achieved was more than 95% using Z-nZVFe-Cu as a heterogeneous Fenton like catalyst. An efficient removal of total organic carbon (TOC) was promoted as compared to zeolite supported iron nano composite (Z-nZVFe) and unsupported nano iron (nZVFe). Electron spin resonance (ESR) detection confirmed the intensity of hydroxyl radicals (OH ) in the system. While benzoic acid (BA), a probe indicator for the quantification of OH , demonstrated the higher intensity of hydroxyl radicals in Z-nZVFe-Cu as compared to Z-nZVFe and nZVFe. The less iron and copper leaching of from Z-nZVFe-Cu presented its higher stability and better catalytic activity, displaying its potential long term applications for TCE degradation in groundwater. [ABSTRACT FROM AUTHOR]

ABSTRACT Trichloroethylene (TCE) is ubiquitous in our living environment, and prenatal exposure to TCE is reported to cause congenital heart disease in humans. Although multiple studies have been performed using animal models, they have limited value in predicting effects on humans due to the unknown species-specific toxicological effects. To test whether exposure to low doses of TCE induces developmental toxicity in humans, we investigated the effect of TCE on human embryonic stem cells (hESCs) and cardiomyocytes (derived from the hESCs). In the current study, hESCs cardiac differentiation was achieved by using differentiation medium consisting of StemPro-34. We examined the effects of TCE on cell viability by cell growth assay and cardiac inhibition by analysis of spontaneously beating cluster. The expression levels of genes associated with cardiac differentiation and Ca2+ channel pathways were measured by immunofluorescence and qPCR. The overall data indicated the following: (1) significant cardiac inhibition, which was characterized by decreased beating clusters and beating rates, following treatment with low doses of TCE; (2) significant up-regulation of the Nkx2.5/Hand1 gene in cardiac progenitors and down regulation of the Mhc-7/cTnT gene in cardiac cells; and (3) significant interference with Ca2+ channel pathways in cardiomyocytes, which contributes to the adverse effect of TCE on cardiac differentiation during early embryo development. Our results confirmed the involvement of Ca2+ turnover network in TCE cardiotoxicity as reported in animal models, while the inhibition effect of TCE on the transition of cardiac progenitors to cardiomyocytes is unique to hESCs, indicating a species-specific effect of TCE on heart development. This study provides new insight into TCE biology in humans, which may help explain the development of congenital heart defects after TCE exposure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1372-1380, 2016. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE), a halogenated organic solvent widely used in industries, is known to cause severe hepatotoxicity. However, the mechanisms underlying TCE hepatotoxicity are still not well understood. It is predicted that membrane proteins are responsible for key biological functions, and recent studies have revealed that TCE exposure can induce abnormal levels of membrane proteins in body fluids and cultured cells. The aim of this study is to investigate the TCE-induced alterations of membrane proteins profiles in human hepatic L-02 liver cells. A comparative membrane proteomics analysis was performed in combination with two-dimensional fluorescence difference gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. A total of 15 proteins were identified as differentially expressed (4 upregulated and 11 downregulated) between TCE-treated cells and normal controls. Among this, 14 of them are suggested as membrane-associated proteins by their transmembrane domain and/or subcellular location. Furthermore, the differential expression of β subunit of adenosine triphosphate synthase (ATP5B) and prolyl 4-hydroxylase, β polypeptide (P4HB) were verified by Western blot analysis in TCE-treated L-02 cells. Our work not only reveals the association between TCE exposure and altered expression of membrane proteins but also provides a novel strategy to discover membrane biomarkers and elucidate the potential mechanisms involving with membrane proteins response to chemical-induced toxic effect. [ABSTRACT FROM AUTHOR]

The role of reactive oxygen species (ROSs) and effect of solution matrix have been investigated for the degradation of trichloroethylene (TCE). Zeolite-supported nano iron (Z-nZVI) was synthesized as an activator to catalyze sodium percarbonate (SPC) with or without hydroxylamine, i.e. as reducing agent (RA). The probe tests confirmed the generation of OH and O in the Z-nZVI activated SPC system in absence of the RA, while the presence of RA significantly increased the generation of OH and O radicals. Scavenger tests demonstrated that OH was the main ROS responsible for TCE degradation, whereas O also participated in TCE degradation. From the solution matrix perspective, the experimental results confirmed significant scavenging effects of Cl (1.0, 10.0, and 100 mmol L) and HCO (1.0 and 10.0 mmol L), whereas the scavenging effects were fairly impeded at 100 mmol L concentration of HCO . On the other hand, a considerable decline in scavenging effect was observed in the presence of RA in tested Cl and HCO concentration ranges. In addition, negligible scavenging effects of NO and SO anions were found in all tested concentrations. The effect of initial solution pH on catalytic activity indicated a significant increase in the TCE degradation in the presence of RA even at higher pH value of 9. The results indicated that the Z-nZVI activated SPC system in presence of RA can effectively degrade chlorinated organic solvents, but it is important to consider the intensive existence of anions in groundwater. [ABSTRACT FROM AUTHOR]

This study primarily focused on the performance of 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethylene (TCE) degradation involving redox reactions in zeolite-supported nanozerovalent iron composite (Z-nZVI)-catalyzed sodium percarbonate (SPC) system in aqueous solution with five different chelating agents (CAs) including oxalic acid (OA), citric acid monohydrate (CAM), glutamic acid (GA), ethylenediaminetetraacetic acid (EDTA), and L-ascorbic acid (ASC). The experimental results showed that the addition of OA achieved almost 100 % degradation of 1,1,1-TCA and TCE. The addition of CAM and GA also significantly increased the contaminant degradation, while excessive addition of them inhibited the degradation. In contrast, EDTA and ASC showed negative impacts on 1,1,1-TCA and TCE degradation, which might be due to the strong reactivity with iron and OH scavenging characteristics. The efficiency with CA addition on 1,1,1-TCA and TCE degradation decreased in the order of OA > CAM > GA > no CAs > EDTA > ASC. The extensive investigations using probe compound tests and scavenger tests revealed that both contaminants degraded primarily by OH and O in chelated Z-nZVI-catalyzed SPC system. The significant improvement in 1,1,1-TCA and TCE degradation efficiency was accredited due to the (i) increase in concentration of Fe and (ii) continuous generation of OH radicals and maintenance of its quantity, ensuring more stability in the aqueous solution. Finally, the complete mineralization of 1,1,1-TCA and TCE in the OA-chelated, Z-nZVI-catalyzed SPC system was confirmed without any chlorinated intermediate by-products detected, demonstrating a great potential of this technique in the application of groundwater remediation. [ABSTRACT FROM AUTHOR]

Building a microscale zero-valent iron (mZVI) reaction zone is a promising in situ remediation technology for restoring groundwater contaminated by trichloroethylene (TCE). In order to determine a suitable modifier that could not only overcome gravity sedimentation of mZVI but also improve its remediation efficiency for TCE, the three biopolymers xanthan gum (XG), guargum (GG), and carboxymethyl cellulose (CMC) were employed to coat mZVI for surface modification. The suspension stability of the modified mZVI and its TCE removal efficiency were systematically investigated. The result indicated that XG as a shear-thinning fluid showed the most remarkable efficiency of preventing mZVI from gravity sedimentation and enhancing the TCE removal efficiency by mZVI. In a 480-h experiment, the presence of XG (3 g L) increased the TCE removal efficiency by 31.85 %, whereas GG (3 g L) and CMC (3 g L) merely increased by 15.61 and 9.69 % respectively. The pH value, Eh value, and concentration of ferrous ion as functions of the reaction time were recorded in all the reaction systems, which indicated that XG worked best in buffering the pH value of the solution and inhibiting surface passivation of mZVI. [ABSTRACT FROM AUTHOR]

An advanced method for the degradation of trichloroethylene (TCE) over Pd/MCM-41 catalysts through a hydrogen-transfer was investigated. Formic acid (FA) was used instead of gaseous H 2 as the hydrogen resource. As a model H-carrier compound, FA has proven to yield less by-products and second-hand pollution during the reaction. Several factors have been studied, including: the property of catalyst supports, Pd loading and size, temperature, initial concentrations of FA and TCE (potential impact on the reaction rates of TCE degradation), and FA decomposition. The intrinsic kinetics for TCE degradation were measured, while the apparent activation energies and the reaction orders with respect to TCE and FA were calculated through power law models. On the basis of kinetics, we assumed a plausible reaction pathway for TCE degradation in which the catalytic degradation of TCE is most likely the rate-determining step for this reaction. [ABSTRACT FROM AUTHOR]

During pregnancy, the placental villous cytotrophoblasts differentiate via cell fusion and multinucleation to create syncytiotrophoblasts, a cell type at the maternal-fetal interface. Apoptosis of syncytiotrophoblasts is associated with adverse pregnancy outcomes. The human trophoblast BeWo cell line has been used as an in vitro model for this differentiation process, also known as syncytialization. In the current study, we exposed unsyncytialized BeWo cells, BeWo cells undergoing syncytialization, and syncytialized BeWo cells to S -(1,2-dichlorovinyl)-L-cysteine (DCVC), a metabolite of the industrial chemical trichloroethylene (TCE). DCVC exposure at 50 μM for 48 h decreased cell viability, increased cytotoxicity, increased caspase 3/7 activity, and increased nuclear condensation or fragmentation in BeWo cells regardless of their differentiation status. Investigating mechanisms of apoptosis, DCVC increased H 2 O 2 abundance and decreased PRDX2 mRNA in all three BeWo cell models. DCVC decreased tumor necrosis factor-receptor 1 (TNF-R1) concentration in media and decreased NFKB1 and PRDX1 mRNA expression in syncytialized BeWo cells only. DCVC decreased BCL2 mRNA expression in syncytializing BeWo cells and in syncytialized BeWo cells only. Decreased LGALS3 mRNA was seen in unsyncytialized BeWo cells only. Together, these data suggest roles for oxidative stress and pro-inflammatory mechanisms underlying apoptosis in BeWo cells with differences depending on differentiation state. [Display omitted] • DCVC stimulated apoptosis in three different differentiation states of BeWo cells. • Magnitude of apoptosis depended on the differentiation state of the BeWo cells. • DCVC decreased PRDX2 and increased H 2 O 2 abundance in all three BeWo models. • DCVC decreased NFKB1 and media TNF-R1 in syncytialized BeWo cells only. • DCVC decreased PRDX1 in syncytialized BeWo cells only. [ABSTRACT FROM AUTHOR]

In this study, Fe, Ni, and Fe/Ni nanoparticles were successfully incorporated in commercial polystyrene cation exchange resin, D072, to form Fe-D072, Ni-D072, and Fe/Ni-D072 composites. The resultant composites were characterized by scanning electron microscopy-energy dispersive spectrometer and X-ray diffraction. For the first time, the resultant composites were used to dechlorinate trichloroethylene (TCE), the target pollutant, in aqueous solution. The effects of initial concentration of TCE and solution pH on TCE removal efficiencies by Fe/Ni-D072 were investigated. The stability and durability of Fe/Ni-D072 were also examined. Results showed that Fe/Ni-D072 with 4% wt of Ni/Fe loading (mass ratio: Ni:Fe = 20:80) possesses superior dechlorination performance compared with TCE to Fe-D072 and Ni-D072. The freshly prepared Fe/Ni-D072 exhibited high reactivity during the dechlorination process of TCE. However, reactivity decreased with increased number of cycles. The leaching of Fe and Ni ions from Fe/Ni-D072 were approximately 0.2 ppm and less than 0.1 ppm, respectively, which are below the maximum acceptable level of Fe and Ni in water (0.3 mg/L for Fe and 0.1 mg/L for Ni) as suggested by the US Environment Protection Agency (EPA). The study confirmed that Fe/Ni-D072 is a potential catalyst to reduce environmental pollutants containing carbon halogen bonds such as TCE. [ABSTRACT FROM AUTHOR]

Chlorinated ethenes such as trichloroethylene (TCE) are common and persistent groundwater contaminants. If contaminated groundwater discharges to a stream, then stream water pollution near the contamination site also becomes a problem. In this respect, the fate and transport of chlorinated ethenes around a stream in an industrial complex were evaluated using the concentration of each component, and hydrogeochemical, microbial, and compound-specific carbon isotope data. Temporal and spatial monitoring reveal that a TCE plume originating from main and local source zones continues to be discharged to a stream. Groundwater geochemical data indicate that aerobic conditions prevail in the upgradient area of the studied aquifer, whereas conditions become anaerobic in the downgradient. The TCE molar fraction is high at the main and local source zones, ranging from 87.4 to 99.2% of the total volatile organic compounds (VOCs). An increasing trend in the molar fraction of cis -1, 2-Dichloroethene ( cis -DCE) and vinyl chloride (VC) was observed in the downgradient zone of the study area. The enriched δ 13 C values of TCE and depleted values of cis -DCE in the stream zone, compared to those of the source zone, also suggest biodegradation of VOCs. Microbial community structures in monitoring wells adjacent to the stream zone in the downgradient area were analyzed using 16S rRNA gene-based pyrosequencing to identify the microorganisms responsible for biodegradation. This was attributed to the high relative abundance of dechlorinating bacteria in monitoring wells under anaerobic conditions farthest from the stream in the downgradient area. The multilateral approaches adopted in this study, combining hydrogeochemical and biomolecular methods with compound-specific analyses, indicate that contaminants around the stream were naturally attenuated by active anaerobic biotransformation processes. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE) has long been well known as a major pollutant that affects both occupational and general environments. Occupational medicamentosa-like dermatitis induced by TCE (OMLDT) is an autoimmune disease, which has become one of the critical occupational health issues in China. In this study, we analyzed 18 OMLDT patients and 29 professional TCE contact people on serum proteomic analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and ClinProTools bioinformatics software. The intensities of 35 protein/peptide peaks were significantly different between TCE contact controls and OMLDT patients. A pattern of six peaks ( m/ z 1,450.33, 1,866.16, 3,262.39, 4,109.55, 5,064.85 and 5,956.57) were selected to construct a diagnostic model to discriminate the OMLDT patients from controls with sensitivity and specificity of both 93.8 %. Our findings provide an alternative proteomic approach to differentiate the OMLDT patients from TCE contact workers with high sensitivity and high specificity, which will be of potential value in clinical diagnosis for occupational disease. [ABSTRACT FROM AUTHOR]

Trace-organic contaminants elimination effectiveness and their removal pathways in a powder-activated carbon-membrane bioreactor (PAC-MBR) used for micro-polluted surface water treatment were investigated in this study. The results showed that PAC-MBR was capable of consolidating DOM elimination, enhancing trace-organic contaminants (2,4,6-trichlorophenol, nitrobenzene and trichloroethylene) removal efficiency, improving permeate biostability, and decreasing bulk organic content and specific fractional components, which was beneficial for membrane fouling mitigation. By series of well-designed batch-tests and estimation, trace-organics removal pathways were analyzed. The primary way of TCE removal was aeration volatilization, while that of NB and 2,4,6-TCP elimination was biodegradation which was greatly affected by biomass content within bulk. PAC addition was a positive way for effective trace-organics removal by increasing mixed solid adsorption capability, especially in start-up phase, and offering beneficial circumstances for biomass enrichment and functional bacteria accumulation. Thus, PAC addition into MBR is a simple and effective strategy to treat micro-polluted water resources. [ABSTRACT FROM AUTHOR]

Xanthan gum-coated microscale zero valent iron (XG-mZVI) is potentially an inexpensive and effective material to promote the degradation of environmental contaminants. The effects of geochemical constituents (humic acid (HA), Ca 2 + / Mg 2 + - HCO 3 - , Na + - Cl - ) on trichloroethylene (TCE) removal using XG-mZVI were investigated using batch experiments to evaluate the potential performance of XG-mZVI in field treatments. TCE was removed from groundwater by adsorption and chemical reduction. In the co-presence of geochemical constituents, TCE adsorption was not significantly impacted, while its reduction rate was increased by the presence of HA (5–20 mg L −1 ), inhibited with increasing Ca(HCO 3 ) 2 and Mg(HCO 3 ) 2 concentrations (0.4–2 mM) and unaffected by NaCl in the range of 10–100 mM. The promotional effect of HA on TCE reduction was primarily due to the Fe-humate complexes in solution that delayed the formation of passivated precipitates. However, the presence of Ca(HCO 3 ) 2 and Mg(HCO 3 ) 2 exerted an opposite effect on TCE reduction by facilitating the formation of passivated precipitates, such as green iron rust. These findings provide insight into the impact mechanism of XG-mZVI reactivity by organic and inorganic geochemical constituents with particular implications for the XG-mZVI degradation of TCE in real groundwater. [ABSTRACT FROM AUTHOR]

A long-lasting emulsified colloidal substrate (LECS) was developed for continuous carbon and nanoscale zero-valent iron (nZVI) release to remediate trichloroethylene (TCE)-contaminated groundwater under reductive dechlorinating conditions. The developed LECS contained nZVI, vegetable oil, surfactants (Simple Green™ and lecithin), molasses, lactate, and minerals. An emulsification study was performed to evaluate the globule droplet size and stability of LECS. The results show that a stable oil-in-water emulsion with uniformly small droplets (0.7 μm) was produced, which could continuously release the primary substrates. The emulsified solution could serve as the dispensing agent, and nZVI particles (with diameter 100–200 nm) were distributed in the emulsion evenly without aggregation. Microcosm results showed that the LECS caused a rapid increase in the total organic carbon concentration (up to 488 mg/L), and reductive dechlorination of TCE was significantly enhanced. Up to 99% of TCE (with initial concentration of 7.4 mg/L) was removed after 130 days of operation. Acidification was prevented by the production of hydroxide ion by the oxidation of nZVI. The formation of iron sulfide reduced the odor from produced hydrogen sulfide. Microbial analyses reveal that dechlorinating bacteria existed in soils, which might contribute to TCE dechlorination. [ABSTRACT FROM AUTHOR]

This report focuses on the enhancement in trichloroethylene (TCE) removal from contaminated groundwater using xanthan gum (XG)-modified, microscale, zero-valent iron (mZVI). Compared with bare mZVI, XG-coated mZVI increased the TCE removal efficiency by 30.37% over a 480-h experimental period. Because the TCE removal is attributed to both sorption and reduction processes, the contributions from sorption and reduction were separately investigated to determine the mechanism of XG on TCE removal using mZVI. The results showed that the TCE sorption capacity of mZVI was lower in the presence of XG, whereas the TCE reduction capacity was significantly increased. The FTIR spectra confirmed that XG, which is rich in hydrophilic functional groups, was adsorbed onto the iron surface through intermolecular hydrogen bonds, which competitively repelled the sorption and mass transfer of TCE toward reactive sites. The variations in the pH, Eh, and Fe 2+ concentration as functions of the reaction time were recorded and indicated that XG buffered the solution pH, inhibited surface passivation, and promoted TCE reduction by mZVI. Overall, the XG-modified mZVI was considered to be potentially effective for the in-situ remediation of TCE contaminated groundwater due to its high stability and dechlorination reactivity. [ABSTRACT FROM AUTHOR]

This study investigates how the feeding pattern of e donors might affect the efficiency of enhanced in situ bioremediation in TCE-contaminated aquifers. A series of lab-scale batch experiments were conducted using butyrate or hydrogen gas (H) as e donor and a TCE-dechlorinating microbial consortium dominated by Dehalococcoides spp. The results of these experiments demonstrate that butyrate is similarly efficient for TCE dechlorination whether it is injected once or in doses. Moreover, the present work indicates that the addition of butyrate in great excess cannot be avoided, since it most likely provide, even indirectly, significant part of the H required. Furthermore, methanogenesis appears to be the major ultimate e accepting process in all experiments, regardless the e donor used and the feeding pattern. Finally, the timing of injection of H seems to significantly affect dechlorination performance, since the injection during the early stages improves VC-to-ETH dechlorination and reduce methanogenic activity. [ABSTRACT FROM AUTHOR]