Abstract  BIOSIS COPYRIGHT: BIOL ABS. PURPOSE: The purpose of this study was to assess the relationship of alcohol consumption and intake of 15 selected micronutrients with risk of liver cirrhosis. METHODS: Data from a case-control study performed in 1989-1990 in central Italy involving 115 incident cases and 167 hospital controls were used. RESULTS: Cases and controls did not differ for mean daily intake of calories, carbohydrates, lipids, and proteins. Significant direct dose-response relationships between the intakes of vitamin A and iron and the risk cirrhosis were observed, while significant protective effects were obtained for the intakes of vitamins B2 (riboflavin) and B12. Different patterns of the joint effect of nutrients and alcohol were also observed. The intakes of vitamin A and iron were significantly associated with the risk of cirrhosis in lifetime teetotalers (odds ratios (OR) and 95% confidence intervals (CI) of 33.6 (1.2-979.9) and 37.9 (1.8-819.4) for higher intake of vitamin A and iron,

Abstract  AIPO(4)-11 was used as catalyst for the synthesis of hisphenol- by Friedel-Crafts condensation of acetone with phenol in presence of carbon tetrachloride and synthesis of cinnamic acid by Knovenagel condensation of aromatic aldehydes with malonic acid in presence of ethyl alcohol.

Abstract  Sheets of paper commonly used for filtration were coated with double layers of HMDS ( hexamethyl disilazane) and n-hexane using a low pressure plasma reactor. The organic compounds formed a thin film with very good adhesion to the substrate; the process produced water-repellent surfaces, with apparent water-contact angles higher than 100degrees and water adsorption around 15 g/m(2). The paper porosity was not altered, indicating that the depositions were conformal. Preliminary tests to investigate the possibility of using the modified paper as a selective membrane for separation of water and organic-polar and non-polar compounds of different chain length were conducted. The non-polar compounds tested were: n-hexane, cyclohexane, heptane, dodecane, benzene and poly( dimethylsiloxane). The polar organic liquids were ethanol, 2-propanol, carbon tetrachloride, acetophenone and phenol. Three types of behaviour were observed: ( a) in the case of water/non-polar mixture, the non-polar compound passed through the modified paper whereas water did not; (b) in the case of acetophenone, phenol and carbon tetrachloride, neither the water nor the polar compound percolated through the modified paper; ( c) in the case of water/2-propanol or ethanol solution, it was observed that a minimum concentration of alcohol was necessary in order for both the alcohol and water to percolate through the paper; in this case the alcohol percolates first, followed by water.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. The oyster mushroom (Pleurotus ostreatus) is widely cultivated, but the volatile compounds it produces are little known. Several methods of isolation of volatile components were compared: extraction by carbon tetrachloride, vacuum distillation, and conveyance by nitrogen flow. The observed order of extraction efficiency was CCl4 and gt; vacuum and gt; N2. Compounds extracted by CCl4 were 3-octanone, 3-octanol, 1-octen-3-ol, benzaldehyde, 1-octanol, benzoic acid, and an unidentified trace component. The extracted mixture of compounds demonstrated strong antibacterial activity against some bacterial strains. Addition of a facsimile mixture containing these volatile compounds to a culture broth resulted in complete inhibition of the eight bacteria used for antibacterial assay. Benzaldehyde, which does not contribute notably to the inhibition of bacterial growth, is formed as a reaction to the stress of CCl4 contact or vacuum dehydration. The amount of benzaldehyde produced may b

Abstract  The printed circuit board (PCB) is an important part of electrical and electronic equipment, and its disposal and the recovery of useful materials from waste PCBs (WPCBs) are key issues for waste electrical and electronic equipment. Waste PCB compositions and their pyrolysis characteristics were analyzed in this study. In addition, the volatile organic compound (VOC) exhaust was controlled by an iron-impregnated alumina oxide catalyst. Results indicated that carbon and oxygen were the dominant components (hundreds mg/g) of the raw materials, and other elements such as nitrogen, bromine, and copper were several decades mg/g. Exhaust constituents of CO, H2, CH4, CO2, and NOx, were 60-115, 0.4-4.0, 1.1-10, 30-95, and 0-0.7mg/g, corresponding to temperatures ranging from 200 to 500°C. When the pyrolysis temperature was lower than 300°C, aromatics and paraffins were the major species, contributing 90% of ozone precursor VOCs, and an increase in the pyrolysis temperature corresponded to a decrease in the fraction of aromatic emission factors. Methanol, ethylacetate, acetone, dichloromethane, tetrachloromethane and acrylonitrile were the main species of oxygenated and chlorinated VOCs. The emission factors of some brominated compounds, i.e., bromoform, bromophenol, and dibromophenol, were higher at temperatures over 400°C. When VOC exhaust was flowed through the bed of Fe-impregnated Al2O3, the emission of ozone precursor VOCs could be reduced by 70-80%.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Chlorofluorocarbon (CFC-113), CHCl3 and CCl4 have been photolysed in the presence of H2O, and the decomposed species scavenged by the reaction with a metal powder. The decomposition of these hazardous compounds was almost 100%. All chlorine atoms were fixed in the form of metal chlorides, and no gaseous product existed except CO2. The scavenging reaction of generated reactive species was brought about by the oxidation of the metal, and hence divalent and trivalent metal compounds showed only insignificant scavenging efficiency.

Abstract  We demonstrated adsorption and reduction of cobalamin(III) (Co(III)) on nano-mackinawite (nFeS) surface and their impact on reductive dechlorination of tetrachloroethene (PCE). The adsorption of Co(III) on the nFeS surface followed Langmuir isotherm and the reduction of Co(III) provided different reactive surface chemical species on nFeS surface. Content of Fe(2+)S on nFeS surface decreased (45.9-14.5%) as Fe(2+)S was oxidized to Fe(3+)S and Fe(3+)O coupled with the surface reduction of Co(III) to cobalamin(II) (Co(II)). S(2-) and S(n)(2-) contents on the nFeS surface also decreased by 48.5% and 82.3%, respectively during the formation of sulfidecobalamin(II) (≡S(2-)Co(II)) by the reactive surface sulfur. PCE was fully degraded in nFeSCo(III) suspension at pH 8.3 in 120 h. The dechlorination kinetic rate constant of PCE in the nFeSCo(III) suspension (k(FeSCo(III))=0.188±0.003 h(-1)) was 145 times greater than that in nFeS suspension, showing a potential role of ≡S(2-)Co(II) as an electron transfer mediator to shuttle electrons for the enhanced reductive dechlorination. PCE was transformed to acetylene and 1,3-butadiene as major products via reductive β-elimination and isomerization reactions, respectively. The experimental findings can provide basic knowledge to identify a reaction mechanism for the enhanced reductive dechlorination of chlorinated organic by biogeochemical reactions possibly observed in natural reducing environments.

Abstract  In this research, we conducted trichloroethylene (TCE) reduction in a column filled with iron and iron-reducing bacteria (IRB) and developed a mathematical model to investigate the critical reactions between active species in iron/IRB/contaminant systems. The formation of ferrous iron (Fe(II)) in this system with IRB and zero-valent iron (ZVI, Fe(0)) coated with a ferric iron (Fe(III)) crust significantly affected TCE reduction and IRB respiration in various ways. This study presents a new framework for transformation property and reducing ability of both dissolved (Fe(II)dissolved) and solid form ferrous iron (Fe(II)solid). Results showed that TCE reduction was strongly depressed by Fe(II)solid rather than by other inhibitors (e.g., Fe(III) and lactate), suggesting that Fe(II)solid might reduce IRB activation due to attachment to IRB cells. Newly exposed Fe(0) from the released Fe(II)dissolved was a strong contributor to TCE reduction compared to Fe(II)solid. In addition, our research confirmed that less Fe(II)solid production strongly supported long-term TCE reduction because it may create an easier TCE approach to Fe(0) or increase IRB growth. Our findings will aid the understanding of the contributions of iron media (e.g., Fe(II)solid, Fe(II)dissolved, Fe(III), and Fe(0)) to IRB for decontamination in natural groundwater systems. Graphical abstract

Abstract  Tetrakis-(4-sulfonatophenyl)porphyrin cobalt was identified as a highly-active reductive dechlorination catalyst for chlorinated ethylenes. Through batch reactor kinetic studies, degradation of chlorinated ethylenes proceeded in a step-wise fashion with the sequential replacement of Cl by H. For perchloroethylene (PCE) and trichloroethylene (TCE), the dechlorination products were quantified and the C₂ mass was accounted for. Degradation of the chlorinated ethylenes was found to be first-order in substrate. Dechlorination trials with increasing catalyst concentration showed a linearly increasing pseudo first-order rate constant which yielded rate laws for PCE and TCE degradation that are first-order in catalyst. The dechlorination activity of this catalyst was compared to that of another water-soluble cobalt porphyrin under the same reaction conditions and found to be comparable for PCE and TCE.

Abstract  Selective redox degradation of chlorinated aliphatics by Fenton reaction in pyrite suspension was investigated in a closed system. Carbon tetrachloride (CT) was used as a representative target of perchlorinated alkanes and trichloroethylene (TCE) was used as one of highly chlorinated alkenes. Degradation of CT in Fenton reaction was significantly enhanced by pyrite used as an iron source instead of soluble Fe. Pyrite Fenton showed 93% of CT removal in 140 min, while Fenton reaction with soluble Fe(II) showed 52% and that with Fe(III) 15%. Addition of 2-propanol to the pyrite Fenton system significantly inhibited degradation of TCE (99% to 44% of TCE removal), while degradation of CT was slightly improved by the 2-propanol addition (80-91% of CT removal). The result suggests that, unlike oxidative degradation of TCE by hydroxyl radical in pyrite Fenton system, an oxidation by the hydroxyl radical is not a main degradation mechanism for the degradation of CT in pyrite Fenton system but a reductive dechlorination by superoxide can rather be the one for the CT degradation. The degradation kinetics of CT in the pyrite Fenton system was decelerated (0.13-0.03 min(-1)), as initial suspension pH decreased from 3 to 2. The formation of superoxide during the CT degradation in the pyrite Fenton system was observed by electron spin resonance spectroscopy. The formation at initial pH 3 was greater than that at initial pH 2, which supported that superoxide was a main reductant for degradation of CT in the pyrite Fenton system.

Abstract  The reactivities of various types of iron mixtures to degrade chlorinated hydrocarbons (PCE, TCE and 1,1,1-TCA) in the form of non-aqueous phase liquids were investigated. The iron mixtures included a mixture of Fe(II) and Portland cement (Fe(II)-C), a mixture of Fe(II), Fe(III) and Ca(OH)(2) (Fe(II/III)-L), and a mixture of Fe(II), Fe(III), Ca(OH)(2), and Portland cement (Fe(II/III)-C). When the same amount of Fe(II) was used, Fe(II)-C was more reactive with chlorinated ethylenes (i.e. PCE and TCE) than Fe(II/III)-L. The reductive pathway for high concentrations of total PCE (i.e. above solubility) with Fe(II)-C was determined to be a combination of two-electron transfer, β-elimination and hydrogenolysis. Increasing the cement dose from 5% to 10% in Fe(II)-C did not affect PCE dechlorination rates, but it did favor the β-elimination pathway. In addition, when Fe(II/III)-C with 5%C was used, PCE dechlorination was similar to that by Fe(II)-C, but this mixture did not effectively degrade TCE. A modified second-order kinetic model was developed and shown to appropriately describe degradation of TCE at high concentrations. Fe(II/III)-L effectively degraded high concentrations of 1,1,1-TCA at rates that were similar to those obtained with Fe(II)-C using 10% C. Moreover, both increasing cement doses and the presence of Fe(III) increased dechlorination rates of 1,1,1-TCA, which was mainly through the hydrogenolysis pathway. The reactivity of Fe(II/III)-L was strongly dependent on the target compound (i.e. less reactivity with TCE, more with 1,1,1-TCA). Therefore, Fe(II/III)-L could be a potential mixture for degrading 1,1,1-TCA, but it should be modified to degrade TCE more effectively.

Abstract  Dechlorination of pentachlorophenol (PCP) by zero-valent iron (Fe-0) and palladium (Pd)/iron (Fe) bimetallic nanoparticles (NPs) immobilized in nylon 6,6/PEG membranes was investigated at room temperature. Pd/Fe bimetallic NPs were synthesized by two different approaches, sequential and simultaneous reduction of trivalent iron (Fe3+) and divalent palladium (Pd2+) ions. Pd/Fe NPs prepared by simultaneous reduction showed a much smaller particle size, only 30 nm in average, and significantly higher reactivity toward PCP dechlorination than the other two materials. Almost 85% PCP removal within 45 min was qualified in terms of both phenol emergence and chlorine ion release. In contrast, dechlorination efficiency by Pd/Fe NPs immobilized by sequential reduction was insignificant. Iron oxides between Fe-0 and Pd-0 during the sequential reduction process impeded their effective contact, and enhanced PCP sorption on membranes. Spectra of X-ray photoelectron spectroscopy confirmed the existence of both Fe-0 and iron oxide on the surface of these three NPs. This investigation has revealed that Pd/Fe NPs immobilized by simultaneous reduction may serve as a suitable medium for in situ remediation, even though it is difficult to avoid the formation of iron oxides.

Abstract  Landfill gas (LFG) was upgraded to pure methane using the adsorption and absorption processes. Different toxic compounds like aromatics and chlorinated compounds were removed using granular activated carbon. The activated carbon adsorbed toxic trace components in the following order: carbon tetrachloride > toluene > chloroform > xylene > ethylbenzene > benzene > trichloroethylene [asymptotic to] tetrachloroethylene. After removing all trace components, the gas was fed to absorption apparatus for the removal of carbon dioxide (CO sub(2)). Two alkanolamines, monoethanol amine (MEA) and diethanol amine (DEA) were used for the removal of CO sub(2) from LFG. The maximum CO sub(2) loading is obtained for 30 wt.% MEA which is around 2.9 mol L super(- 1) of absorbent solution whereas for same concentration of DEA it is around 1.66 mol L super(- 1) of solution. 30 wt% MEA displayed a higher absorption rate of around 6.64 x 10 super(- 5) mol L super(- 1) min super(- 1). DEA displayed a higher desorption rate and a better cyclic capacity as compared to MEA. Methane obtained from this process can be further used in the natural gas network for city.

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 atmospheric burden of methyl chloroform (CH(3)CCl(3)) is still considerable due to its long atmospheric lifetime, although CH(3)CCl(3) emissions have declined considerably since it was included into the Montreal Protocol. Moreover, CH(3)CCl(3) emissions are used to estimate hydroxyl radical (OH) levels, trends, and hemispheric distributions, and thus the mass balance of the trace gas in the atmosphere is critical for characterizing OH concentrations. Salt marshes may be a potential sink for CH(3)CCl(3) due to its anoxic environment and abundant organic matter in sediments. In this study, seasonal dynamics of CH(3)CCl(3) fluxes were measured using static flux chambers from April 2004 to January 2005, along an elevational gradient of a coastal salt marsh in eastern China. To estimate the contribution of higher plants to the gas flux, plant aboveground biomass was experimentally harvested and the flux difference between the treatment and the intact was examined. In addition, the flux was analyzed in relation to soil and weather conditions. Along the elevational gradient, the salt marsh generally acted as a net sink of CH(3)CCl(3) in the growing season (from April to October). The flux of CH(3)CCl(3) ranged between -3.38 and -32.03 nmol m(-2)d(-1) (positive for emission and negative for consumption), and the maximum negative rate occurred at the cordgrass marsh. However, the measurements made during inundation indicated that the mudflat was a net source of CH(3)CCl(3). In the non-growing season (from November to March), the vegetated marsh was a minor source of CH(3)CCl(3) when soil was frozen, the emission rate ranging from 3.43 to 7.77 nmol m(-2)d(-1). However, the mudflat was a minor sink of CH(3)CCl(3) whether it was frozen or not in the non-growing season. Overall, the coastal salt marsh in eastern China was a large sink for the gas, because the magnitude of consumption rate was lager than that of emission, and because the duration of the growing season was longer than that of the non-growing season. Plant aboveground biomass had a great effect on the flux. Comparative analysis showed that the direction and magnitude of the effect of higher plants on the flux of CH(3)CCl(3) depended on timing of sampling vegetation type. In the growing season the plant biomass decreased the gas flux and acted as a large sink of the gas, whereas it presented as a minor source in the non-growing season. However, the mechanism underlying plant uptake process is not clear. The CH(3)CCl(3) flux was positively related to the dissolved salt concentration and organic matter content in soil, as well as light intensity, but it was negatively related to soil temperature, sulfate concentrations, and initial ambient atmospheric concentrations of CH(3)CCl(3). Our observations have important implications for estimation of the tropospheric lifetime of CH(3)CCl(3) and global OH concentration from the global budget concentration of CH(3)CCl(3).

Abstract  A laboratory size quartz reactor has been used to burn methane, LPG (liquid petroleum gas) and aromatic hydrocarbon vapors in a bubbling fluidized bed. Most measurements and observations were made for lean mixtures of fuel and air with quartz sand in the bed, but in some experiments NO, NO2, or CCl4 were introduced with the fuel, the stoichiometry was varied or the bed material changed. The quantities monitored were the bed temperature at two levels and the freeboard concentrations of O-2, CO2, CO, NO, NO2, and in some runs, of hydrocarbons. An attempt was made to relate the measurements to the sound level and to visual observations. The results obtained suggest that with the air excess, lambda, constant at 1.4 and with the bed at above similar to850degreesC, the fuel can be fully oxidized and [CO] very low. [NO] is also low and does not increase even if the temperature is raised by another 150 to 200degreesC. However, such a stable combustion process can be perturbed by adding a chemical inhibitor. With a suitable bed material it is possible to lower [CO] and [NO] in the freeboard to similar to1 ppm. At lower temperatures, with [CO] high, the conversion of NO to NO, takes place. Most of the observations are consistent with the dominance of gas-phase reactions in the bubbles, but some effects can only be accounted for by the participation of heterogeneous chemical reactions. (C) 2002 by The Combustion Institute.

Abstract  We have shown that dietary bluefin tuna skin (TUS) protects against carbon tetrachloride (CCl4)-induced hepatic damage in mice. The CCl4-induced necrotic area was decreased in mice fed a TUS-containing diet. Consistent with the decreased necrotic area, dietary TUS markedly lowered the elevated serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and the thiobarbituric acid-reactive substance (TBARS) formation induced by CCl4 injection. TUS diets also decreased phosphorylation of inhibitory kappa B-alpha and blocked the translocation of nuclear factor-kappa B to the nucleus. TUS is composed mainly (80.7 %) of type I collagen, and our results revealed that dietary tuna collagen peptides (TUCP) attenuated the increased hepatic necrotic area, serum AST and ALT activities, and liver TBARS levels induced by CCl4, similar to TUS, thus enabling us to attribute the hepatoprotective action of TUS in CCl4-intoxicated mice to tuna collagen. Therefore, TUS and TUCP may be potential food resources that are capable of alleviating hepatitis symptoms.

Abstract  Zerovalent iron nanoparticles (Fe(0) NPs or nZVI) synthesized by reductive precipitation in aqueous solution (Fe/FeO) differ in composition and reactivity from the NPs obtained by reductive precipitation in the presence of a S-source such as dithionite (Fe/FeS). To compare the redox properties of these types of NPs under a range of environmentally relevant solution conditions, stationary powder disk electrodes (PDEs) made from Fe/FeO and Fe/FeS were characterized using a series of complementary electrochemical techniques: open-circuit chronopotentiometry (CP), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). The passive films on these materials equilibrate within minutes of first immersion and do not show further breakdown until >1 day of exposure. During this period, the potentials and currents measured by LPR and LSV suggest that Fe/FeS undergoes more rapid corrosion and is more strongly influence by solution chemical conditions than Fe/FeO. Chloride containing media were strongly activating and natural organic matter (NOM) was mildly passivating for both materials. These effects were also seen in the impedance data obtained by EIS, and equivalent circuit modeling of the electrodes composed of these powders suggested that the higher reactivity of Fe/FeS is due to greater abundance of defects in its passive film.

Abstract  Quinone moieties in humic substances have previously been shown to serve as extracellular electron acceptors in different metabolic pathways. Here we show that the humic acid analogue antraquinone-2,6-disulfonate (AQDS) can also serve as an electron donor in the microbial reductive dechlorination of TCE to cis-DCE. In a bioelectrochemical system (BES), equipped with a glassy carbon electrode (cathode) polarized at -250mV vs. SHE, electrically reduced AQDS served as the shuttle of electrons between the electrode surface and the dechlorinating bacteria. Interestingly, AQDS selectively stimulated only the first step of the TCE dechlorination sequence, leading to the formation of cis-DCE. Bioelectrochemical experiments carried out using a dechlorinating culture, highly enriched in the cis-DCE dechlorinating microorganism Dehalococcoides spp., confirmed the inability of reduced AQDS to serve as an electron donor for cis-DCE dechlorination. The results of this study have implications for the development of bioelectrochemical systems for groundwater remediation, as well as for the biogeochemical fate of chlorinated solvents in humic substances-rich subsurface environments.

Abstract  Decomposition of dichlorodifluoromethane (CCl2F2 or CFC-12) in a radiofrequency) (RF) plasma system is demonstrated. The CCl2F2 decomposition fractions (eta (CCl2F2)) and mole fractions of detected products in the effluent gas stream of CCl2F2/O-2/Ar and CCl2F2/H-2/Ar plasma, respectively: have been determined. The experimental parameters including input power wattage, O-2/CCl2F2 Or H-2/ CCl2F2 ratio, operational pressure, and CCl2F2 feeding concentration were investigated The main carbonaceous product in the CCl2F2/O-2/Ar plasma system was CO2, while that in the CCl2F2/H-2/Ar plasma system was CH4 and C2H2. Furthermore, the possible reaction pathways were built-up and elucidated in this study. The results of the experiments showed that the highly, electronegative chlorine and fluorine could easily separate from the CCl2F2 molecule and combine with the added reaction gas. This led to the reactions terminated with the CO2, CH4, and C2H2 formation, because of their high bonding strength. The addition of hydrogen would form a preferential pathway for the HCl and HF formations, which were thermodynamically stable diatomic species that would limit the production of CCl3F, CClF3, CF4, and CCl4. In addition, the HCl and HF could be removed by neutral or scrubber method. Hence, a hydrogen-based RF plasma system provided a better alternative to decompose CCl2F2.

Abstract  NF3 decomposition in the absence of water over Al2O3, Fe2O3 Co3O4 and NiO, and transition metal oxides (Fe2O3 Co3O4 and NiO) coated Al2O3 reagents was investigated The results show that Al2O3 is an active reagent for NF3 decomposition with 100% conversion lasting for 8 5 h at 400 degrees C Fe2O3, Co3O4 and NiO coated Al2O3 reagents are superior to bare Al2O3 and 5%Co3O4/Al2O3 has a high reactivity with NF3 full conversion maintaining for 10 5 h It is suggested that the presence of transition metal oxide is beneficial to the reactivity of Al2O3 and results in a significant enhancement in the fluorination of Al2O3

Abstract  An experiment was performed in a carbon tetrachloride (CT)- and nitrate-contaminated aquifer at Schoolcraft, MI, to evaluate bioaugmentation with Pseudomonas stutzeri KC, a denitrifying bacterium that degrades CT without producing chloroform (CF). A test section of the aquifer was treated to create pH conditions favorable for KC and then inoculated with culture grown aerobically on site. Activity was sustained with pulses of acetate-amended groundwater, followed by "chase" pulses of acetate-free water. In regions with effective substrate delivery, KC was detected, nitrate levels fell by 85%, pH levels increased, and CT levels decreased by similar to 65%, with no significant increase in CF. After 3 weeks, denitrification and CT transformation activity decreased, and KC was no longer detected in groundwater from four wells. Loss of denitrification was attributed to the acetate-free chase. Upon eliminating the chase, CT transformation resumed, and KC was detected, but CF production was also observed, implicating indigenous organisms as agents of transformation. Final sediment analyses indicated 60-88% CT removal, little CF, and persistent KC. This work demonstrates subsurface pH adjustment, subsurface transport of KC, assimilation of KC into the aquifer community, CT removal without CF production after inoculation, and CF formation when KC activity declined.