Abstract  A high-pressure (20 MPa) and high-temperature (350-degrees-C) liquid water processing environment was used to treat various wastewaters and model compounds. Organics were converted to methane and carbon dioxide in the presence of catalysts. Functional types included hydrocarbons, both aliphatic and aromatic; phenolics and other oxygenates; chlorinated hydrocarbon solvents; and sodium salts of organic acids. Tests with aqueous nickel ion showed negligible catalytic activity. Noncatalytic hydrolysis of sodium cyanide, carbon tetrachloride, and chloroform was also demonstrated. Ammonium destruction was proven by reaction with nitrate at these processing conditions. Several examples of test results with actual industrial waste streams showed that this process can be effectively used with catalysts to clean wastewater and recover waste organics as useful fuel gas.

Abstract  Halogenated synthetic organic compounds are used in a wide variety of pesticides, solvents, refrigerants, fire retardants, and paints that cause extensive pollution to the air, surface water, groundwater, and soils. Carbon tetrachloride (CCl) is a typical halogenated synthetic organic compound that has been suspected to be toxic and carcinogenic and to cause ozone depletion. In the present work, molecular-level destruction of CCl by copper acetate was investigated by extended X-ray absorption fine structural spectra, X-ray absorption near-edge spectra, X-ray photoelectron spectroscopy, and X-ray diffraction spectroscopy. Experimentally, the Cl species dissociated from CCl were abstracted by copper species and formed CuCl. At 473 to 533 K, reaction products (copper chloride) aggregated on the surfaces of CuO, which might cause the obstruction of further CCl destruction. Due to the insertion of Cl species into the matrix of CuO, the bond distances of Cu-O and Cu-(O)-Cu were increased by 0.3 to 0.4 Å and 0.3 to 0.6 Å, respectively. However, at 603 K, because 79.5% of the Cu was in the CCl destruction solid products, the coordination number of Cu-(O)-Cu increased to 5.6. Molecular level investigations are a key to identifying the mechanisms of the CCl destruction process. In addition, identification of the molecular characteristics of the products may help in safe disposal of the toxic substances. The success of this study paved the way for the destruction of halogenated organic compounds by copper acetate.

Abstract  A series of samples of magnetic fluids stabilized with low-molecular weight polypropylene glycol (PPG) of different molecular masses were synthesized. The use of PPG allowed the maximum extension of the carrier fluid range to include ethyl- and butyl-acetate, ethanol, butanol, acetone, carbon tetrachloride, toluene, kerosene and PPG itself. Magnetic and rheological properties of the samples were investigated. Based on the results of investigation it has been concluded that magnetic nanoparticles are covered by a monolayer of surfactant molecules. At low temperatures the propanol-based sample preserves fluidity upto -115 degrees C. Measurement of critical temperatures of other base fluids showed that alcohols are the best carrier medium. Coagulation stability of the ethanol-based ferrocolloid with respect to water and kerosene was explored. It has been found that kerosene, whose fraction by weight exceeds 22.5%, does not mix with the colloid. This effect can be used to produce magneto-controllable extractors of ethyl alcohol. Under the action of water the colloid coagulates, which allows one to substitute the carrier fluid and to separate the colloid into fractions. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  A unique type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant was prepared and used for dechlorination of monochlorobenzene (MCB). The sample Ni(B)/Fe(B) was synthesized by an electroless plating method, in which nanoscale Ni(B) was deposited on the surface of nanoscale Fe(B) synthesized by chemical reduction. The results suggest that the nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant has higher dechlorination efficiency than Ni/Fe(B) catalytic reductant prepared by replacing Fe(B) with Ni(2+) in aqueous solution. The Ni content was found to be an important factor in catalytic dechlorination, with the dechlorination rate increasing with Ni content. The electroless plating method improve the efficiency of the Ni(2+) in the solution. Dechlorination takes place with the existence of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant via a pseudo-first-order reaction.

Abstract  Adsorption isotherms of chlorobenzene, chloroform and carbon tetrachloride vapors on undoped SiO(2), and metal-doped Ag/SiO(2), Cu/SiO(2) and Fe/SiO(2) substrates were measured in the temperature range of 398-593K. These substrates were prepared from a typical sol-gel technique in the presence of metal dopants that rendered an assortment of microporous-mesoporous solids. The relevant characteristic of these materials was the different porosities and micropore to mesopore volume ratios that were displayed; this was due to the effect that the cationic metal valence exerts on the size of the sol-gel globules that compose the porous solid. The texture of these SiO(2) materials was analyzed by X-ray diffraction (XRD), FTIR, and diverse adsorption methods. The pore-size distributions of the adsorbents confirmed the existence of mesopores and supermicropores, while ultramicropores were absent. The Freundlich adsorption model approximately fitted the chlorinated compounds adsorption data on the silica substrates by reason of a heterogeneous energy distribution of adsorption sites. The intensity of the interaction between these organic vapors and the surface of the SiO(2) samples was analyzed through evaluation of the isosteric heat of adsorption and standard adsorption energy; from these last results it was evident that the presence of metal species within the silica structure greatly affected the values of both the amounts adsorbed as well as of the isosteric heats of adsorption.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. The potential of the expanded-bed granular activated carbon (GAC) anaerobic reactor in treating a high strength waste containing RCRA volatile organic compounds (VOCs) was studied. A total of six VOCs, methylene chloride, chlorobenzene, carbon tetrachloride, chloroform, toluene and tetrachloroethylene, were fed to the reactor in a high strength matrix of background solvents. Performance was evaluated. The reactor was found to effect excellent removal of all VOCs (97%). Chloroform, while itself removed at levels in excess of 97%, was found to inhibit the degradation of acetate and acetone, two of the background solvents. Without any source of chloroform in the feed, excellent COD removals were obtained in addition to near-complete removal of all the VOCs.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. The kinetics of the reactions between tetrachloromethane (CCl4),1,2-dichloroethane (C2H4Cl2), or chlorobenzene (C6H5Cl) and sodium carbonate were investigated using evolved gas analysis-Fourier transform infrared spectroscopy. Sodium carbonate reacted with CCl4 between 600 and 900 K to form over 90% carbon dioxide (CO2) and less than 10% tetrachloroethene (C2Cl4). This reaction followed the three-dimensional diffusion mechanism and had an activation energy of 105 | 10 kJ/mol and a steric factorunshtein diffusion mechanism and had an activation energy of 100 | 10 kJ/mol and a steric factor of approximately 104 min-1. Benzene was produced from the reaction between chlorobenzene and sodium carbonate at temperatures above 800 K. This reaction followed the three-dimensional diffusion mechanism and had an activation energy of 80 | 10 kJ/mol and a steric factor of approximately 500 min-1.

Abstract  There are many well documented similarities in the anatomy and physiology of mammalian species. There are also numerous examples in which the equilibrium distribution of foreign chemicals in the body appears to follow principles of thermodynamic partitioning with relatively minor interspecies variations to be expected. Information on metabolic pathways and their kinetic characteristics can be obtained from a variety of in vitro systems. It may be possible to use such information in pharmacokinetic models that incorporate existing knowledge and judgment to predict pharmacokinetics in intact animals including man.

Abstract  The mechanisms responsible for ethanol-mediated teratogenesis have not been resolved. However, possible etiologies include the local formation of the teratogen acetaldehyde or oxygen radicals by fetal ethanol-oxidizing enzymes. As alcohol dehydrogenases are expressed at very low concentrations in human embryonic tissues, the ethanol-inducible P450 enzyme, CYP2E1, could be the sole catalyst of fetal ethanol oxidation. With this in mind, we examined the expression of this P450 in liver samples from fetuses ranging in gestational age from 16 to 24 weeks. Immunoblot analysis of fetal liver microsomes revealed the presence of a protein immunoreactive with CYP2E1 antibodies that exhibited a slightly lower molecular weight than that found in adult liver samples. Embryonic CYP2E1 expression was further confirmed by the reverse transcriptase reaction with RNA from a 19-week gestational fetal liver used as template. Catalytic capabilities of human fetal microsomes were assessed by measurement of the rate of ethanol oxidation to acetaldehyde, which were 12-27% of those exhibited by adult liver microsomes. Immunoinhibition studies with CYP2E1 antibodies revealed that the corresponding antigen was the major catalyst of this reaction in both fetal and adult tissues. We then assessed whether embryonic CYP2E1 was, like the adult enzyme, inducible by xenobiotics. Treatment of primary fetal hepatocyte cultures with either ethanol or clofibrate demonstrated a 2-fold increase in CYP2E1 levels compared with untreated cells. Collectively, our results indicate that CYP2E1 is present in human fetal liver, that the enzyme is functionally similar to CYP2E1 from adults, and that fetal hepatocyte CYP2E1 is inducible in culture by xenobiotics, including ethanol. Because fetal CYP2E1 mediates ethanol metabolism, the enzyme may play a pivotal role in the local production of acetaldehyde and free radicals, both of which have potential deleterious effects on the developing fetus.

Abstract  A physiologically based pharmacokinetic model which describes the behavior of inhaled styrene in rats accurately predicts the behavior of in baled styrene in humans. The model consists of a series of mass-balance differential equations which quantify the time course of styrene concentration within four tissue groups representing (1) highly perfused organs, (2) moderately perfused tissues such as muscle. (3) slowly perfused fat tissue, and (4) organs with high capacity to metabolize styrene (principally liver). The pulmonary compartment of the model incorporates uptake of styrene controlled by ventilation and perfusion rates and the blood:air partition coefficient The metabolizing tissue group incorporates saturable Michaelis-Menten metabolism controlled by the biochemical constants Vmax and Km. With a single set of physiological and biochemical constants, the model adequately simulates styrene concentrations in blood and fat of rats exposed to 80, 200, 600, or 1200 ppm styrene (data from previously published studies). The simulated behavior of styrene is particularly sensitive to changes in the constants describing the fat tissue group, and to the maximum metabolic rate described by Vmax, The constants used to simulate the fate of stvrene in rats were scaled up to represent humans. Simulated styrene concentrations in blood and exhaled air of humans are in good agreement with previously published data. Model simulations show that styrene metabolism is saturated at inhaled concentrations above approximately 200 ppm in mice, rats, and humans. At inhaled concentrations below 200 ppm, the ratio of styrene concentration in blood to inhaled air is controlled by perfusion limited metabolism. At inhaled concentrations above 200 ppm. This ratio is controlled by the blood:air partition coefficient and is not linearly related to the ratio attained at lower (nonsaturating) exposure concentrations. These results show that physiologically based pharmacokinetic models provide a rational basis with which (1) to explain the relationship between blood concentration and air concentration of an inhaled chemical, and (2) to extrapolate this relationship from experimental animals to humans.

Abstract  Simultaneous sampling of chlorinated hydrocarbons (CHs) and monocyclic aromatic hydrocarbons (MAHs), potentially harmful to humans and/or responsible for the formation of ozone and secondary particles, in dew water and in the ambient air was carried out from August 2004 to July 2005 in Hino City, situated in the western part of Greater Tokyo, Japan. CHs were less contained in dew water than MAHs. Toluene (volume-weighted mean concentration, VWM: 4.77 nM) and m,p-Xylenes (VWM: 5.07 nM) except dichloromethane, which was abnormally high (VWM: 1.14 μM), were abundant among eleven VOCs determined in dew water. Chloroform, carbon tetrachloride, 1,2-dichloroethane, and benzene were not detected in dew water during the study period. Dew water contained higher amounts of VOCs than would have been expected from the ambient gas-phase concentrations and the temperature-corrected Henry's law constants. Following the determination method of humic substances in river water proposed by Hiraide et al. [Hiraide, M., Shima, T., Kawaguchi, H., 1994. Separation and determination of dissolved and particulate humic substances in river water. Mikrochim. Acta 113, 269–276], the VWM of soluble humic and fulvic acid fractions in dew water was found to be 1.00 mg/L and 0.87 mg/L (n = 20), respectively, while the VWM of particulate humic and fulvic acid fractions was found to be 0.61 mg/L and 0.42 mg/L (n = 20), respectively. Surface tension decreased with an increase in dissolved fulvic acid fraction in dew water, indicating that humic-like substances with relatively lower molecular weight, which is soluble in acid solution, could be an effective surface-active species within dew water. The enrichment factors, which were defined as the ratio of the observed VOCs concentration to the estimated, were over 102 for MAHs except for benzene and increased as the increment of total humic-like substances (HULIS) concentration (the sum of humic and fulvic acid fractions in both dissolved and particulate form) normalized by total inorganic ion concentration in dew water. Our results indicate that total HULIS in dew water could enhance the dissolution of atmospheric VOCs into dew droplets.

Abstract  The neurobehavioral effects of 10 known toxicants were examined as part of a multidisciplinary screening battery. The toxicants included carbaryl (CAR), triadimefon (TDM), heptachlor (HEP), chlordane (CDN), diethylhexyl phthalate (DEHP), carbon tetrachloride (CCl4), phenol, trichloroethylene (TCE), tetrachloroethylene (PER or perchlorethylene), and dichloromethane (DCM or methylene chloride). A functional observational battery and motor activity measurements were conducted before exposure, at specified times after an acute exposure, and during and after 14-d exposure. Severity scoring analysis was used to generate profiles of effect. The pesticides, CAR, TDM, HEP, and CDN, displayed the most acute neurotoxicity and were active at lower proportions of their respective acute LD50 values than were the solvents or the industrial chemicals. Although CAR and TDM showed little or no neurobehavioral effects with repeated dosing, cumulative neurotoxicity and lethality were evident with HEP and CDN. Phenol produced acute convulsive effects, and the most prominent finding with repeated exposure was lethality. DEHP displayed no neurobehavioral toxicity. The organic solvents, TCE, PER, CCl4, and DCM, produced various degrees of general nervous system depression following acute administration of high dose levels. Repeated dosing produced little or no effect with TCE or PER, marked physiological changes with CCl4, and cumulative toxicity and lethality with DCM. Some results of these studies were unexpected and should provide impetus for further research. Overall, these findings illustrate the utility of these screening methods.

Abstract  PESTAB. The environmental impact of major chlorinated aliphatic hydrocarbons is discussed. Chlorform, carbon tetrachloride, trichloroethylene, perchloroethylene, and trichloroethane are very widely distributed in the environment at a concentration level of 1 ppt. The concentrations of DDT and polychlorinated biphenyls in fatty tissues are at least three orders of magnitude greater than those of the industrial solvents. A population may breather air, drink water, and consume food containing trace quantities of these materials. All these compounds are fairly rapidly degraded in the environment to carbon dioxide, water, and chloride ion. There is no evidence for their significant bioaccumulation, via the food chains, to higher trophic levels.

Abstract  Corrosion of iron pipes leads to the release of ferrous iron, Fe(II), and the formation of iron oxides, such as goethite and magnetite, on the pipe surface. Fe(II), a potent reductant when associated with iron oxide surfaces, can mediate the reduction of halogenated organic compounds. Batch experiments were performed to investigate the kinetics and pathways of the degradation of selected chlorinated disinfection byproducts (DBPs) by Fe(II) in the presence of synthetic goethite and magnetite. Trichloronitromethane was degraded via reduction, while trichloroacetonitrile, 1,1,1-trichloropropanone, and trichloroacetaldyde hydrate were transformed via both hydrolysis and reduction. Chloroform and trichloroacetic acid were unreactive. Observed pseudo-first-order reductive dehalogenation rates were influenced by DBP chemical structure and identity of the reductant. Fe(II) bound to iron minerals had greater reactivity than either aqueous Fe-(II) or structural Fe(II) present in magnetite. For DBPs of structure Cl sub(3)C-R, reductive dehalogenation rate constants normalized by the surface density of Fe(II) on both goethite and magnetite correlated with the electronegativity of the -R group and with one electron reduction potential. In addition to chemical transformation, sorption onto the iron oxide minerals was also an important loss process for 1,1,1-trichloropropanone.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. Testing of the permeation resistance of seven glove and suit materials against commercially available chlorosilanes was performed using the ASTM F739-91 standard test method. In addition to determining the performance of the barriers, the question of the validity of selection of protective clothing based on performance against the hydrolysis product (hydrogen chloride) was investigated.The chlorosilanes used as challenge agents were methylhydrogendichlorosilane, dimethyldichlorosilane, trifluoropropylmethyldichlorosilane, trichlorosilane, silicontetrachloride, methyltrichlorosilane, phenyltrichlorosilane, and vinyltrichlorosilane. Protective glove barriers tested were Neoprene rubber, nitrile rubber, butyl rubber, Viton polymer, 4H laminate, Silver Shield laminate, and latex rubber. Protective clothing barriers were polyvinyl chloride (PVC), Tychem 7500, CPF IV, Barricade, Responder, Saranex 23P laminated Tyvek and Chemrel. Latex performed poorly, with breakthrough note

Abstract  The effect of acetone (67641) on trichloroethylene (79016) and carbon-tetrachloride (56235) hepatotoxicity was studied in rats. Male Sprague-Dawley-rats were administered 0, 0.25, 0.75, or 1.5 milliliters per kilogram (ml/kg) acetone orally. Eighteen hours later they were injected intraperitoneally with 0 or 0.25ml/kg trichloroethylene or 0.1 or 0.6ml/kg carbon-tetrachloride alone or in combination. The rats were killed 24 hours later, the livers were removed, and assayed for hepatotoxicity by determining plasma alanine-aminotransferase (ALT) activity, total bilirubin, and by histological examination. Acetone alone or combined with trichloroethylene had no effect on ALT activity or total bilirubin. ALT activity was higher in rats treated with trichloroethylene plus either dose of carbon-tetrachloride than with carbon-tetrachloride alone. Bilirubin concentration was increased only by trichloroethylene plus 0.6ml/kg carbon-tetrachloride. Acetone enhanced carbon-tetrachloride liver injury to a greater extent than trichloroethylene. Acetone markedly potentiated liver injury induced by trichloroethylene plus carbon-tetrachloride in a dose/dependent manner. Histological analyses showed no statistical differences in the percentages of normal, degenerated, or necrotic hepatocytes between carbon-tetrachloride or trichloroethylene treated rats and controls. Trichloroethylene plus carbon-tetrachloride significantly reduced the percentage of normal hepatocytes and increased the percentage of degenerated or necrotic hepatocytes. Acetone pretreated rats given the carbon-tetrachloride plus trichloroethylene mixtures showed a significant dose related decrease in the percentage of normal hepatocytes and a dose related increase in the percentage of necrotic hepatocytes. The authors conclude that trichloroethylene can potentiate carbon-tetrachloride induced liver injury. Acetone exerts a potentiating effect on the hepatotoxic response of the carbon-tetrachloride plus trichloroethylene mixtures.

Abstract  We review the experimental evidence for various shapes of dose-response relationships for carcinogens and summarize those experiments that give the most information on relatively low doses. A brief review of some models is given to illustrate the shapes of dose-response curve expected from them. Our major interest is in the use of dose-response relationships to estimate risks to humans at low doses, and so we pay special attention to experimentally observed and theoretically expected nonlinearities. There are few experimental examples of nonlinear dose-response relations in humans, but this may simply be due to the limitations in the data. The several examples in rodents, even though for high dose data, suggest that nonlinearity is common. In some cases such nonlinearities may be rationalized on the basis of the pharmacokinetics of the test compound or its metabolites.

Abstract  Ongoing publicity about methyl tertiary butyl ether (MTBE) suggests that this chemical is of greater concern than other contaminants commonly found in drinking water. The purpose of this article is to evaluate the available MTBE data in context with other volatile organic compounds (VOCs) that are detected in public drinking water sources in California. We find that of the 28 VOCs with a primary maximum contaminant level (MCL) in California, 21 were found in 50 or more drinking water sources from 1985 to 2002. Over the last 10 years, the most frequently detected VOCs were chloroform, tetrachloroethylene (PCE), and trichloroethylene (TCE), which were found in about 9-15% of all sampled drinking water sources. These same chemicals were found to have the highest mean detected concentrations over the last 5 years, ranging from 13 to 15 g/L. Many VOCs were also found to routinely exceed state and federal drinking water standards, including benzene and carbon tetrachloride. By comparison, MTBE was found in approximately 1% of sampled drinking water sources for most years, and of those drinking water sources found to contain MTBE from 1998 to 2002, over 90% had detected concentrations below California's primary MCL of 13 g/L. Relative to the other VOCs evaluated, MTBE has the lowest estimated California cancer potency value, and was found to pose one of the least cancer risks from household exposures to contaminated drinking water. These findings suggest that MTBE poses an insignificant threat to public drinking water supplies and public health in California, particularly when compared to other common drinking water contaminants.

Abstract  The effects of ethanol (64175) on allyl-alcohol (107186) and carbon-tetrachloride (56235) hepatotoxicity were studied in rats. The purpose of the study was to assess the potential for ethanol to interact with known liver toxicants when used as a solvent in the dosing vehicle. Male Fischer-344-rats were gavaged with 0, 0.05, 0.1, 0.2, or 0.5 milliliter per kilogram (ml/kg) ethanol or 21mg/kg allyl-alcohol or 20mg/kg carbon-tetrachloride alone or in combination daily for 14 days. Body weight was monitored. The rats were killed 24 hours after the last dose and livers were removed, weighed, and assayed for cytochrome P-450 (P450) and reduced glutathione (GSH). Liver sections were examined for histopathological changes. Blood samples were collected and analyzed for serum lactate-dehydrogenase (LDH), alkaline-phosphatase (ALP), alanine-aminotransferase (ALT), and aspartate-aminotransferase (AST). Ethanol alone did not significantly affect body weight gain, hepatic P450 or GSH content, or serum ALT, AST, LDH, or ALP activity. It did not cause any histologically evident liver damage, but did cause a dose related decrease in absolute and relative liver weight. The apparent threshold for these effects was between 0.05 and 0.1ml/kg. Allyl-alcohol alone caused significant increasesin absolute and relative liver weight and hepatic GSH concentration, and it induced periportal hepatocellular vacuolar degeneration. Carbon-tetrachloride alone caused significant increases in absolute and relative liver weight and serum ALT, AST, and ALP activities. It also induced centrilobular hepatocellular degeneration and necrosis. Coadministration with ethanol did not alter the effects of allyl-alcohol or carbon-tetrachloride. No significant interaction of ethanol with allyl-alcohol was determined, but a small interactive effect on body weight occurred with 0.5ml/kg ethanol and carbon-tetrachloride. The authors conclude that subacute concurrent exposure of ethanol with carbon-tetrachloride or allyl-alcohol at ethanol concentrations typically used in dosing vehicles does not cause an interactive effect or hepatotoxicity.

Abstract  Epidemiologic evidence on the relationship between organic solvents and cancer is reviewed. In the 1980s, more than a million persons were potentially exposed to some specific solvents in the United States; in Canada, 40 percent of male cancer patients in Montreal had experienced exposure to solvents; in the Finnish population, one percent was regularly exposed. There is evidence for increased risks of cancer following exposure to: trichloroethylene (for the liver and biliary tract and for non-Hodgkin's lymphomas); tetrachloroethylene (for the esophagus and cervix--although confounding by smoking, alcohol, and sexual habits cannot be excluded--and non-Hodgkin's lymphoma); and carbon tetrachloride (lymphohematopoietic malignancies). An excess risk of liver and biliary tract cancers was suggested in the cohort with the high exposure to methylene chloride, but not found in the other cohorts where an excess risk of pancreatic cancer was suggested. 1,1,1-trichloroethane has been used widely, but only a few studies have been done suggesting a risk of multiple myeloma. A causal association between exposure to benzene and an increased risk of leukemia is well-established, as well as a suggested risk of lung and nasopharynx cancer in a Chinese cohort. Increased risks of various gastrointestinal cancers have been suggested following exposure to toluene. Two informative studies indicated an increased risk of lung cancer, not supported by other studies. Increased risks of lymphohematopoietic malignancies have been reported in some studies of persons exposed to toluene or xylene, but not in the two most informative studies on toluene. Occupation as a painter has consistently been associated with a 40 percent increased risk of lung cancer. (With the mixed exposures, however, it is not possible to identify the specific causative agent[s].) A large number of studies of workers exposed to styrene have evidenced no consistent excess risk of all lymphohematopoietic malignancies, although the most sensitive study suggested an excess risk of leukemia among workers with a high exposure.

Abstract  Carbon tetrachloride (CT) batch degradation experiments by four commercial irons at neutral pH indicated that iron metal (Fe0) purity affected both rates and products of CT transformation in anaerobic systems. Surface-area-normalized rate constants and elemental composition analysis of the untreated metals indicate that the highest-purity, least-oxidized Fe0 was the most reactive on a surface-area-normalized basis in transforming CT. There was also a trend of increasing yield of the hydrogenolysis product chloroform (CF) with increasing Fe0 purity. Impurities such as graphite in the lower purity irons could favor the alternate CT reaction pathway, dichloroelimination, which leads to completely dechlorinated products. High pH values slowed the rates of CT disappearance by Peerless Fe0 and led to a pattern of decreasing CF yields as the pH increased from 7 to 12.9. The Fe/O atomic ratio vs depth for Peerless Fe0 filings equilibrated at pH 7 and 9.3, obtained by depth profiling analysis with X-ray photoelectron spectroscopy, indicated differences in the average oxide layer composition as a function of pH, which may explain the pH dependence of rate constants and product yields. Groundwater constituents such as HS-, HCO3-, and Mn2+ had a slight effect on the rates of CT degradation by a high-purity Fe0 at pH 7, but did not strongly influence product distribution, except for the HS amended Fe0 where less CF was produced, possibly due to the formation of carbon disulfide (CS2)

Abstract  The attenuation potential of methane (CH4) and of selected volatile organic Compounds (VOCs) was compared in four types of compost materials using dynamic flow column experiments over a period of 255 d. Garden waste compost mixed with wood chips showed the highest steady-state CH4 oxidation rate (161 g m(-2) d(-1)), followed by a commercial compost product Supermuld (110 g m(-2) d(-1)). In the column containing the highest fraction of compost (compost/sand mixed in 1: 1), CH4 oxidation declined significantly during the period of operation, probably due to clogging by formation of exopolymeric substances. After 40 d of operation, CH, production was observed. All the VOCs tested were degraded. CFC-11 (CCl3F) and HCFC-21 (CCl2FH) were anaerobically degraded by reductive dechlonnation, generating HCFC-31 (CClFH2) and HFC-41 (CFH3), which were both aerobically degraded in the oxic portion of the columns. Overall, the highest removal of VOCs was observed in the column containing the compost/ wood chip mixture. This study demonstrates that biocovers consisting of compost materials have the potential to attenuate trace gas emissions from landfills. Copyright (C) 2009 by the American Society of Agronomy, Crop Science Society of America, and Sol I Science Society of America. All rights reserved. No part of this periodical maybe reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.

Abstract  Samples of mother's milk were collected from Bayonne, NJ; Jersey City, NJ; Pittsburgh, PA; Baton Rouge, LA; and Charleston, WV, and analyzed for volatile (purgeables) and semivolatile (extractable) organics using glass capillary gas chromatography/mass spectrometry/computer. In the volatile fraction, 26 halogenated hydrocarbons, 17 aldehydes, 20 ketones, 11 alcohols, 2 acids, 3 ethers, 1 epoxide, 14 furans, 26 other oxygenated compounds, 4 sulfur-containing compounds, 7 nitrogen-containing compounds, 13 alkanes, 12 alkenes, 7 alkynes, 11 cyclic hydrocarbons, and 15 aromatics were found, including major peaks for hexanal, limonene, dichlorobenzene, and some esters. The levels of dichlorobenzene appeared to be significantly higher in the samples from Jersey City and Bayonne than in samples from other sites. Jersey City samples also appeared to have significantly higher levels of tetrachloroethylene. Charleston and Jersey City samples appeared to have significantly higher levels of chloroform; however, chloroform was observed in the blanks at about 20% of that in the samples. Due to the small sample size and lack of control over the solicitation of sample donors, the data cannot be used to extrapolate to the general population. Fewer semivolatile compounds of interest were found. Polychlorinated naphthalenes, polybrominated biphenyls, chlorinated phenols, and other compounds were specifically sought and not detected (limit of detection about 20-100 ng/mL milk). Polychlorinated biphenyls (PCBs) and DDE were found.

Abstract  Results of C-6-C-12 hydrocarbon measurements at three sites in the southern part of The Netherlands, a polluted region in Western Europe, are presented. The measurements were carried out over the period March 1991-February 1997. The concentrations at the sites, with 100-150 km distance between them, are quite similar and they are predominantly determined by large-scale transport. The concentrations in this part of the country are substantially higher than those observed at a coastal site in the north of The Netherlands, but much lower compared to the concentrations in cities and near streets. A distinct difference between the trends of aromatics and aliphatics was observed. The concentrations of the aromatic components display trends that are systematically 4-5% yr(-1) lower than the trends of the aliphatics, which is possibly related to the increased use of catalysts in cars and, partly, to an enhanced atmospheric chemical activity. For the chlorinated species the trends are highly significant. The trend of 1,1,1-trichloroethane is in the order of 8-12% yr(-1) downward while for tetrachloromethane an annual downward trend of 4-6% is found. These downward trends suggest that measures have been taken to fulfil the requirements of the Montreal Protocol to ban the production of these species in a few years time from now. (C) 1999 Elsevier Science Ltd. All rights reserved.