Abstract  A solar-driven, photocatalyzed degradation system using TiO2 slurry and immobilized systems was constructed and applied to the degradation of trichloroethylene (TCE) contaminated water using TiO2 with solar light. The experiments were carried out under constant weather conditions on a sunny day. Solar photocatalytic treatment efficiency of the solar light/TiO2 slurry system was compared with that of the solar light/TiO2 immobilized system. The operation of the solar light/TiO2 slurry and immobilized systems showed 100% (TiO2 slurry system), 80% (TiO2 immobilized system) degradation of the TCE after 6 h, with a chloride production yield of approximately 89% (TiO2 slurry system), 72% (TiO2 immobilized system). The oxidants such as H2O2 and S2O8(2-) in the TiO2 slurry and immobilized systems increased TCE degradation rate by suppressing the electron/hole recombination process. The degradation rate and relative toxicity reduction of TCE followed the order of solar light/TiO2 slurry + S2O8(2-) > solar light/TiO2 slurry + H2O2 > solar light/TiO2 immobilized + S2O8(2-) > solar light/TiO2 slurry > solar light/TiO2 immobilized + H2O2 > solar light/TiO2 immobilized. Finally, following to the toxicity result, the acute toxicity was reduced by below toxicity endpoint (EC50 concentration) following the treatment. It means that many of the metabolites of TCE reduction are less toxic to Vibrio fischeri than the parent compound. Based on these results, TCE can be efficiently and safely treated in a solar-driven, photocatalyzed degradation system.

Abstract  The feasibility of the use of short-wavelength UV (254+185 nm) irradiation and TiO2 catalyst for photodegradation of gaseous toluene was evaluated. It was clear that the use of TiO2 under 254+185 nm light irradiation significantly enhanced the photodegradation of toluene relative to UV alone, owed to the combined effect of photochemical oxidation in the gas phase and photocatalytic oxidation on TiO2. The photodegradation with 254+185 nm light irradiation was compared with other UV wavelengths (365 nm (black light blue lamp) and 254 nm (germicidal UV lamp)). The highest conversion and mineralization were obtained with the 254+185 nm light. Moreover, high conversions were achieved even at high initial concentrations of toluene. Catalyst deactivation was also prevented with the 254+185 nm light. Regeneration experiments with the deactivated catalyst under different conditions revealed that reactive oxygen species played an important role in preventing catalyst deactivation by decomposing effectively the less reactive carbon deposits on the TiO2 catalyst. Simultaneous elimination of photogenerated excess ozone and residual organic compounds was accomplished by using a MnO2 ozone-decomposition catalyst to form reactive species for destruction of the organic compounds.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Viruses are abundant and dynamic members of the marine microbial community, and it is important to understand their role in the ecology of natural microbial populations. We have previously found lysogenic bacteria to be a significant proportion (43 %) of the cultivable heterotrophic microbial population. As the majority of marine bacteria are not cultivable using standard plating methods, we measured the proportion of marine lysogenic bacteria in natural communities by prophage induction. Mitomycin C, UV radiation, sunlight, temperature and pressure were used to induce prophage in lysogenic bacteria from estuarine, coastal and oligotrophic offshore environments. To determine if hydrocarbon pollutants may cause the induction of marine lysogens, aromatic and aliphatic hydrocarbons (including Bunker C #6 fuel oil, phenanthrene, naphthalene, pyrene, and trichloroethylene) were also used as inducing agents. Induction was most often found in estuarine environments, where vira

Abstract  Non-thermal plasma processing is one of the most hopeful air-cleaning technologies to remove toxic gas contaminants in air. The historical background of the non-thermal plasma related with the electrostatics is described and the fundamental experimental system including the reactor designs and their power supplies is introduced. Some experimental results suggested the high potential of the plasma processing to decompose those toxic materials. Recent progress of the plasma technologies is reviewed. The decomposition of the dilute volatile organic compounds (VOCs) is main target of the process in this paper. The oxidation ability of the plasma is very strong (stronger than the ozone) and key points for practical usage of the process are, reliability of the process, energy efficiency of the plasma (economy) and post-processed gas treatments after the plasma processing. To improve the energy efficiency of the plasma process, combination with the catalysts is also discussed. A laser-induced fluorescence (LIF) technology is also shown as a new diagnosis of the plasma reaction. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  This paper reports comprehensive studies on the mixed assembly of bis-(trialkoxybenzamide)-functionalized dialkoxynaphthalene (DAN) donors and naphthalene-diimide (NDI) acceptors due the cooperative effects of hydrogen bonding, charge-transfer (CT) interactions, and solvophobic effects. A series of DAN as well as NDI building blocks have been examined (wherein the relative distance between the two amide groups in a particular chromophore is the variable structural parameter) to understand the structure-dependent variation in mode of supramolecular assembly and morphology (organogel, reverse vesicle, etc.) of the self-assembled material. Interestingly, it was observed that when the amide functionalities are introduced to enhance the self-assembly propensity, the mode of co-assembly among the DAN and NDI chromophores no longer remained trivial and was dictated by a relatively stronger hydrogen-bonding interaction instead of a weak CT interaction. Consequently, in a highly non-polar solvent like methylcyclohexane (MCH), although kinetically controlled CT-gelation was initially noticed, within a few hours the system sacrificed the CT-interaction and switched over to the more stable self-sorted gel to maximize the gain in enthalpy from the hydrogen-bonding interaction. In contrast, in a relatively less non-polar solvent such as tetrachloroethylene (TCE), in which the strength of hydrogen bonding is inherently weak, the contribution of the CT interaction also had to be accounted for along with hydrogen bonding leading to a stable CT-state in the gel or solution phase. The stability and morphology of the CT complex and rate of supramolecular switching (from CT to segregated state) were found to be greatly influenced by subtle structural variation of the building blocks, solvent polarity, and the DAN/NDI ratio. For example, in a given D-A pair, by introducing just one methylene unit in the spacer segment of either of the building blocks a complete change in the mode of co-assembly (CT state or segregated state) and the morphology (1D fiber to 2D reverse vesicle) was observed. The role of solvent polarity, structural variation, and D/A ratio on the nature of co-assembly, morphology, and the unprecedented supramolecular-switching phenomenon have been studied by detail spectroscopic and microscopic experiments in a gel as well as in the solution state and are well supported by DFT calculations.

Abstract  Tetrachloroethylene (PCE) and trichloroethylene (TCE), common industrial solvents, are among the most frequent contaminants found in groundwater supplies. Due to the potential toxicity and carcinogenicity of chlorinated ethylenes, knowledge about their transformation potential is important in evaluating their environmental fate. The results of this study confirm that PCE can be transformed by reductive dehalogenation to TCE, dichloroethylene, and vinyl chloride (VC) under anaerobic conditions. In addition, [14C]PCE was at least partially mineralized to CO2. Mineralization of 24% of the PCE occurred in a continuous-flow fixed-film methanogenic column with a liquid detention time of 4 days. TCE was the major intermediate formed, but traces of dichloroethylene isomers and VC were also found. In other column studies under a different set of methanogenic conditions, nearly quantitative conversion of PCE to VC was found. These studies clearly demonstrate that TCE and VC are major intermediates in PCE biotransformation under anaerobic conditions and suggest that potential exists for the complete mineralization of PCE to CO2 in soil and aquifer systems and in biological treatment processes.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. The use of granular iron for in situ degradation of dissolved chlorinated organic compounds is rapidly gaining acceptance as a cost-effective technology for ground water remediation. This paper describes the first field demonstration of the technology, and is of particular importance since it provides the longest available record of performance (five years). A mixture of 22% granular iron and 78% sand was installed as a permeable "wall" across the path of a contaminant plume at Canadian Forces Base, Borden, Ontario. The major contaminants were trichloroethene (TCE, 268 mg) and tetrachloroethene (PCE, 58 mg/L). Approximately 90% of the TCE and 86% of the PCE were removed by reductive dechlorination within the wall, with no measurable decrease in performance over the five year duration of the test. Though about 1% of the influent TCE and PCE appeared as dichloroethene isomers as a consequence of the dechlorination of TCE and PCE, these also degraded within the iron-sand m

Abstract  BIOSIS COPYRIGHT: BIOL ABS. This paper develops a generalized kinetic model for two-phase systems involving reactions in one phase with product partitioning into a second phase, and applies it to the reductive dehalogenation of trichloroethylene using two systems. The generalized approach can be used for a variety of catalyst choices, including zero-valent metals. With vitamin B12, the model includes specific reaction pathways for the reductive dehalogenation of TCE combined with the partitioning of reactants, intermediates, and products between the gas and liquid phases. The model has been used to study the effect of various parameters on the process effectiveness, which otherwise are very difficult to conceive through experimental analysis. In the case of zero-headspace system with zero-valent iron, sorption effects are included to incorporate the partitioning onto the solid surface. A new parameter, 'fractional active site concentration' is introduced to incorporate the differences in reactive

Abstract  The effective concentrations of 15 chemicals, inhibiting the cell growth of the alga Scenedesmus subspicatus by I0 % and 50 % during 96 hours, have been investigated in a static test under controlled laboratory conditions.

Abstract  Excess molar enthalpies H-m(E) and excess molar volumes V-m(E) Of diethyl carbonate + some alkoxyethanol mixtures have been det;ermined by an LKB flow microcalorimeter and an Anton Paar density meter as a function of mole fraction of diethyl carbonate at (298.15 and 313.15) K. The alkoxyethanols are 2-methoxyethanol, 2-ethoxyethanol, 2-buthoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, and 2-(2-butoxyethoxy)-ethanol, respectively.

Abstract  The gas phase photocatalytic degradation of trichloroethylene (TCE) was studied over two kinds of TiO(2), as thin films prepared by the sol-gel process. Dichloroacetyl chloride (DCAC), phosgene and carbon monoxide were confirmed to be intermediates, The detection conditions of DCAC, a main but unstable intermediate, were investigated in different experimental conditions by using in situ FTIR measurement and gas chromatography. Reaction intermediates were different depending on the activity of the photocatalyst. (C) 1997 Elsevier Science Ltd.

Abstract  A simple, economical, rapid and sensitive analytical method has been developed for the simultaneous determination of endosulfan (alpha- and beta-) and its metabolites (endosulfan ether, endosulfan hydroxy ether, endosulfan lactone, endosulfan alcohol and endosulfan sulphate) in complex samples, such as soil and urine, based on ultrasound assisted dispersive liquid-liquid microextraction (UA-DLLME) followed by gas chromatography-mass spectrometric (GC-MS) analysis. The method parameters have been optimized using response surface design experiments. Trichloroethylene (TCE) and acetone were chosen as extraction and disperser solvents respectively. After UA-DLLME, the sediment phase obtained was directly analyzed by GC-MS without any further cleanup and preconcentration procedure. Several factors which can affect the UA-DLLME extraction were screened and optimized by 2(7-4) Plackett-Burman design (PBD) and central composite design (CCD) experiments respectively. Based on these experiments the optimized parameters for UA-DLLME extraction were as follows: extraction solvent, (TCE, 58 mu L), disperser solvent (acetone, 1.27 mL) and ionic strength (Na2SO4, 7%, w/v). Intra-and inter-day precision were expressed as percent relative standard deviation (% RSD) and were found to be less than 6.33%. The limit of detection (LOD) of all the analytes in soil and urine were found to be in the range of 0.316-2.494 ng g(-1) and 0.049-0.514 ng mL(-1) respectively. The proposed method was successfully applied in the analysis of soil samples contaminated with endosulfan. The method may find wide application for the routine determination of endosulfan and its metabolites in environmental and biological samples.

Abstract  Chloro-based volatile organic compounds (VOCs) are known to exert noxious effects on the environment, and their destruction by catalytic combustion, for example, accompanies a production of hydrochloric acid (HCl) that damages the catalyst. We have been interested in complete removal of VOCs by our system based on thermally activated oxide semiconductors (i.e., catalysts) such as Cr sub(2)O sub(3), TiO sub(2), NiO, alpha-Fe sub(2)O sub(3). In the present investigation, we have fundamentally studied the decomposition process of dichloromethane (CH sub(2)Cl sub(2): DCM) and trichloroethylene (CHCCl sub(3); TCE) on the basis of the mass- and Raman spectra in an attempt to identify the formation temperature of HCl. Then, we found that the decomposition of DCM and TCE starts at about 100 and 200[deg]C, respectively; whereas HCl is abruptly formed at a critical temperature of about 350[deg]C in both compounds. Based on this result, we have optimized the operation temperature below 300[deg]C for Cr sub(2)O sub(3)-impregnated honeycomb systems and achieved the complete removal of DCM and TCE that accompanies no formation of HCl.

Abstract  This study examined the photocatalytic oxidation of gas-phase trichloroethylene (TCE) and 2-propanol, at indoor levels, over titanium dioxide (TiO2) irradiated with light-emitting diodes (LED) under different operational conditions. TiO2 powder baked at 450 degrees C exhibited the highest photocatalytic decomposition efficiency (PDE) for TCE, while all photocatalysts baked at different temperatures showed similar PDEs for 2-propanol. The average PDEs of TCE over a three hour period were four, four, five, and 51% for TiO2 powders baked at 150, 250, 350, and 450 degrees C, respectively. The average PDEs of 2-propanol were 95, 97, 98, and 96% for TiO2 powders baked at 150, 250, 350, and 450 degrees C, respectively. The ratio of anatase at 2 theta = 25.2 degrees to rutile at 2 theta = 27.4 degrees was lowest for the TiO2 powder baked at 450 degrees C. Although the LED-irradiated TiO2 system revealed lower PDEs of TCE and 2-propanol when compared to those of the eight watt, black-light lamp-irradiated TiO2 system, the results for the PDEs normalized to the energy consumption were reversed. Other operational parameters, such as relative humidity, input concentrations, flow rate, and feeding type were also found to influence the photocatalytic performance of the UV LED-irradiated TiO2 system when applied to the cleaning of TCE and 2-propanol at indoor air levels.

Abstract  This study evaluated the application of a continuous-flow photocatalytic reactor for the control of two mobile-derived pollutants, methyl-tertiary butyl ether (MTBE) and naphthalene, present at in-vehicle levels. Variables tested for this study included the hydraulic diameter (HD), stream flow rate (SFR), relative humidity (RH), and feeding type (FT). The fixed parameters included contaminant concentration, ultraviolet light source, and the weight of TiO2. In all experimental conditions the adsorption process reached equilibrium within 30 to 180 min for the target compounds, and the outlet concentrations of the photocatalytic oxidation (PCO) reactor while operating reached a steady state within 60 to 180 min. The degradation of the target compounds was dependent on RH, HD, FT, or SFR. The PCO system exhibited high degradation (up to nearly 100% for certain conditions) and mineralization efficiencies of target compounds, suggesting that this system can effectively be employed to improve indoor air quality. Moreover, it was confirmed that trichloroethylene at urban-ambient level also could enhance the degradation efficiency of naphthalene when applying the PCO technology inside vehicles.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Byproduct formation in ozonation processes is of interest, especially in the area of drinking water, similar to the concerns regarding the health effects of disinfection byproducts generated by chlorine and other oxidants used for that purpose. Chlorinated olefins increasingly contaminate our drinking water resources, and the byproducts formed by ozone were determined here. For a better understanding of the underlying mechanisms, some other olefins were included in this study. The rate constants of the reaction of ozone with ethene and some of its methyl- and chlorine-substituted derivatives in aqueous solution have been measured by stopped-flow (rate constants in units of dm3 mol-1 s-1): tetramethylethene,106; propene, 8 chloride, 1.4dichloropropene, 2.6chloroethene, 110; trichloroethene 14. From these data, it is concluded that the rate of reaction is mainly governed by the electron density of the C C double bond and that steric effects must be minor in compariso

Abstract  Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench‐top reactors and in serum bottle tests. Three continuously mixed daily batch‐fed reactor systems were evaluated: anaerobic, aerobic, and sequential‐anaerobic‐aerobic (sequential). Glucose, acetate, benzoate, and phenol were fed as growth substrates to both the anaerobic and aerobic systems. Methane and toluene were also added to the aerobic systems to induce cometabolic degradation of the feed CACs. The anaerobic culture degraded seven of the feed CACs. The specialized aerobic cultures degraded all but three of the highly chlorinated CACs. The sequential system outperformed either of the other systems alone by degrading 10 of the feed CACs: chloroform, carbon tetrachloride, 1,1‐dichloroethane, 1,1,1‐trichloroethane, hexachloroethane, 1,1‐dichloroethylene, trans‐1,2‐dichloroethylene, trichloroethylene, perchloroethylene, and 1,2,3‐trichloropropane, plus the anaerobic metabolites: dichloromethane and cis‐1,2‐dichloroethylene. Sequential treatment did not show significant removal of 2‐chloropropene, or 1,1‐dichloropropene. Cultures from each of the reactors were used in bottle tests to determine relative CAC degradation rates. Maximum degradation rates observed for individual CACs ranged from 20 to 150 μg per gram volatile suspended solids per day.

Abstract  The present study focused on evaluation of activated persulfate (PS) anion (S(2)O(8)(2-)) oxidative degradation of benzene, toluene, ethylbenzene, and xylene (constituents of gasoline and known collectively as BTEX) contamination. The results indicated that BTEX were effectively oxidized by PS in aqueous and soil slurry systems at 20 degrees C. PS can be activated thermally, or chemically activated with Fe(2+) to form the sulfate radical (SO(4)(-)) with a redox potential of 2.4V. The degradation rate constants of BTEX were found to increase with increased persulfate concentrations. For two PS/BTEX molar ratios of 20/1 and 100/1 experiments, the observed aqueous phase BTEX degradation half-lives ranged from 3.0 to 23.1 days and 1.5 to 20.3 days in aqueous and soil slurry systems, respectively. In the interest of accelerating contaminant degradation, Fe(2+) and chelated Fe(2+) activated persulfate oxidations were investigated. For all iron activation experiments, BTEX and persulfate degradations appear to occur almost instantaneously and result in partial BTEX removals. It is speculated that the incomplete degradation reaction may be due to the cannibalization of SO(4)(-) in the presence of excess Fe(2+). Furthermore, the effects of various chelating agents including, hydroxylpropyl-beta-cyclodextrin (HPCD), ethylenediaminetetraacetic acid (EDTA), and citric acid (CA) on maintaining available Fe(2+) and activating PS for the degradation of benzene were studied. The results indicated that HPCD and EDTA may be less susceptible to chelated Fe(2+). In contrast, CA is a more suitable chelating agent in the iron activated persulfate system and with a PS/CA/Fe(2+)/B molar ratio of 20/5/5/1 benzene can be completely degraded within a 70-min period.

Abstract  A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the mechanisms for removal of TCE is anaerobic biodegradation. This study aimed at evaluating the performance of the pilot-scale Biowall after its installation. Data from over four years' monitoring indicated that the Biowall greatly changed geochemistry in the study area and stimulated TCE removal. The concentration of TCE in the Biowall and downgradient of the Biowall was greatly reduced as compared to that in ground water upgradient of the Biowall, while the concentration of cis-DCE in the Biowall and downgradient of the Biowall was much higher than that observed upgradient of the Biowall. Over time, the concentration of vinyl chloride in the Biowall and downgradient of the Biowall increased. Dehalococcoides DNA was detected within and downgradient of the Biowall, corresponding to the observation that vinyl chloride was produced at these locations. Results from a tracer study indicated that the regional groundwater flow pattern ultimately determined the flow direction in the area around the Biowall. The natural groundwater velocity was estimated at an average of 0.060 +/- 0.015 m/d.

Abstract  A series of batch tests were performed and the impacts of environmental conditions and phase change on the sorption of volatile organic compounds (VOCs) were investigated. Benzene, trichloroethylene, tetrachloroethylene, and ethylbenzene were selected as target VOCs. Sorption of VOCs onto tire powder was well demonstrated by a linear-partitioning model. Water-tire partition coefficients of VOCs (not tested in this study) could be estimated using a logarithmic relationship between observed water-tire partition coefficients and octanol-water partition coefficients of the VOCs tested. The target VOCs did not seem to compete with other VOCs significantly when sorbed onto the tire powder for the range of concentrations tested. The influence of environmental conditions, such as pH and ionic strength also did not seem to be significant. Water-tire partition coefficients of benzene, trichloroethylene, tetrachloroethylene, and ethylbenzene decreased as the sorbent dosage increased. However, they showed stable values when the sorbent dosage was greater than 10 g/L. Air-tire partition coefficient could be extrapolated from Henry's law constants and water-tire partition coefficient of VOCs.

Abstract  1,4-Dioxane is a probable human carcinogen, and an important emerging water contaminant. In this study, the biodegradation of dioxane by 20 bacterial isolates was evaluated, and 13 were found to be capable of transforming dioxane. Dioxane served as a growth substrate for Pseudonocardia dioxanivorans CB1190 and Pseudonocardia benzenivorans B5, with yields of 0.09 g protein g dioxane(-1) and 0.03 g protein g dioxane(-1), respectively. Cometabolic transformation of dioxane was observed for monooxygenase-expressing strains that were induced with methane, propane, tetrahydrofuran, or toluene including Methylosinus trichosporium OB3b, Mycobacterium vaccae JOB5, Pseudonocardia K1, Pseudomonas mendocina KR1, Ralstonia pickettii PKO1, Burkholderia cepacia G4, and Rhodococcus RR1. Product toxicity resulted in incomplete dioxane degradation for many of the cometabolic reactions. Brief exposure to acetylene, a known monooxygenase inhibitor, prevented oxidation of dioxane in all cases, supporting the hypothesis that monooxygenase enzymes participated in the transformation of dioxane by these strains. Further, Escherichia coli TG1/pBS(Kan) containing recombinant plasmids derived from the toluene-2- and toluene-4-monooxygenases of G4, KR1 and PKO1 were also capable of cometabolic dioxane transformation. Dioxane oxidation rates measured at 50 mg/L ranged from 0.01 to 0.19 mg hr(-1) mg protein(-1) for the metabolic processes, 0.1-0.38 mg hr(-1) mg protein(-1) for cometabolism by the monooxygenase-induced strains, and 0.17-0.60 mg hr(-1) mg protein(-1) for the recombinant strains. Dioxane was not degraded by M. trichosporium OB3b expressing particulate methane monooxygenase, Pseudomonas putida mt-2 expressing a toluene side-chain monooxygenase, and PseudomonasJS150 and Pseudomonas putida F1 expressing toluene-2,3-dioxygenases. This is the first study to definitively show the role of monooxygenases in dioxane degradation using several independent lines of evidence and to describe the kinetics of metabolic and cometabolic dioxane degradation.

Abstract  In this study, the formation of by-products resulting from the decomposition of trichloroethylene with a negative DC glow discharge has been investigated. By combining the qualitative data from mass spectrometry and Fourier-transform infrared spectroscopy, the formation of phosgene, dichloroacetylchloride and trichloroacetaldehyde have been confirmed as incomplete oxidation products. Hydrogen chloride, chlorine, carbon monoxide and carbon dioxide were also detected. Also, formation of ozone was found in the outlet stream. Based on this information, it is possible to chose an appropriate catalyst to combine with non thermal plasma. In this way emission of harmful, incomplete oxidation products can be further reduced at a lower energy cost.

Abstract  Groundwater has been extensively exploited worldwide but is now confronted by a variety of problems, including groundwater depletion and contamination, that threaten its sustainable use as a clean water source. Groundwater is one of the major sources of water for domestic, agricultural and industrial uses, and provides 13% of the total annual water supply in Korea. Annual groundwater use has continuously increased from 2.57 billion m3 in 1994 to 3.72 billion m3 in 2007, of which 48.1% was consumed for domestic purposes. However, due to imprudent groundwater development and inappropriate management, Korea has confronted some critical groundwater problems, including extensive water level decline and quality deterioration caused by petroleum hydrocarbons and chlorinated solvents. Among 193 national groundwater deep-monitoring wells nationwide, 62% showed decreasing water levels over the period 2004-2008. Soil and groundwater contamination by petroleum hydrocarbons was detected at a great number of military bases and public facilities, which drew national attention and complaints. The presence of high levels of radionuclides such as uranium and radon in groundwater has awakened controversy on their health effects. Increasing outbreaks of massive gastroenteritis were attributed to noroviruses in contaminated groundwater, and raised public health concerns. In addition, chlorinated solvents, especially trichloroethylene (TCE), have been frequently found in urban and industrial groundwaters, further adding to the burdens of environmental authorities. Consequently, these groundwater-related environmental issues have forced the Korean government and relevant authorities to urgently devise mitigation plans to secure a sustainable future use of groundwater resources. This paper provides details of the groundwater issues and implications for appropriate development and management.

Abstract  Biotransformation of trichloroethylene (TCE) in a soil sample was examined in sealed vials. A soil sample was collected from the ground inside the metal welfare factory; it was located in the area where groundwater was contaminated by a degreaser, TCE, and cis-1,2-dichloroethylene (cis-DCE), which had not been used in the vicinity. TCE was transformed into cis-DCE in 1 week in the collected unsterilized soil suspension. On the other hand, TCE did not degrade in the sterilized soil suspension. When 0.05 ml soil suspension was transferred to another sterilized soil suspension, this transformation was observed. This reaction was stopped by heating in boiling water for 10 min. Therefore, this transformation was considered to be due to a microbial dechlorination. The trans-1,2-dichloroethylene, 1,1-dichloroetheylene and vinyl chloride were not detected by this TCE biotransformation. The cis-DCE did not further degrade at least in 3 weeks. It can therefore be presumed that cis-DCE contained in groundwater near the factory is a biotransformation product of TCE.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MICROORGANISMS CHLOROPHENOLS KRAFT PULP WASTEWATER CONTAMINATION ENVIRONMENTAL POLLUTION SOIL TOXICITY BIOTECHNOLOGY REMEDIATION FRESH WATER