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2007-5-10 Metabolic Profile Biomarkers of Metal Contamination in a Sentinel Terrestrial Species Are Applicable Across Multiple Sites Jacob G. Bundy,* Hector C. Keun, Jasmin K. Sidhu, David J. Spurgeon, Claus Svendsen, Peter Kille, and A. John Morgan Department of Biomolecular Medicine, Division of Surgery, Oncology, Reproductive Biology and Anaesthetics (SORA), Faculty of Medicine, Sir Alexander Fleming Building, Imperial College London, London SW7 2AZ, Centre for Ecology and Hydrology, Monks Wood, Abbots Ripton, Huntingdon PE28 2LS, and Cardiff School of Biosciences, Main Building, Cardiff University, Park Place, Cardiff CF10 3TL, Wales, United Kingdom Received for review January 5, 2007 Revised manuscript received March 15, 2007 Accepted March 21, 2007 Abstract: In this study, we addressed the question of whether an omic approach could genuinely be useful for biomarker profile analysis across different field sites with different physicochemical characteristics. We collected earthworms (Lumbricus rubellus) from seven sites with very different levels of metal contamination and prevailing soil type and analyzed tissue extracts by 1H nuclear magnetic resonance spectroscopy. Pattern recognition analysis of the data showed that both site- and contaminant-specific effects on the metabolic profiles could be discerned. Zinc was identified as the probable major contaminant causing a metabolic change in the earthworms. Individual sites could be resolved on the basis of NMR spectral profiles by principal component analysis; these site differences may also have been caused by additional abiotic factors such as soil pH. Despite an inevitable degree of confounding between site and contaminant concentrations, it was possible to identify metabolites which were correlated with zinc across all different sites. This study therefore acts as a proof of principle for the use of NMR-based metabolic profiling as a diagnostic tool for ecotoxicological research in polluted field soils. -------------------------------------------------------------------------------- Emissions from Laboratory Combustion of Wildland Fuels: Emission Factors and Source Profiles L.-W. Antony Chen,* Hans Moosmüller, W. Patrick Arnott, Judith C. Chow, John G. Watson, Ronald A. Susott, Ronald E. Babbitt, Cyle E. Wold, Emily N. Lincoln, and Wei Min Hao Division of Atmospheric Sciences, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada, and Fire Sciences Laboratory, Rocky Mountain Research Station, USDA Forest Service, Missoula, Montana Received for review October 4, 2006 Revised manuscript received February 23, 2007 Accepted March 22, 2007 Abstract: Combustion of wildland fuels represents a major source of particulate matter (PM) and light-absorbing elemental carbon (EC) on a national and global scale, but the emission factors and source profiles have not been well characterized with respect to different fuels and combustion phases. These uncertainties limit the accuracy of current emission inventories, smoke forecasts, and source apportionments. This study investigates the evolution of gaseous and particulate emission and combustion efficiency by burning wildland fuels in a laboratory combustion facility. Emission factors for carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbon (THC), nitrogen oxides (NOx), PM, light extinction and absorption cross sections, and spectral scattering cross sections specific to flaming and smoldering phases are reported. Emission factors are generally reproducible within ±20% during the flaming phase, which, despite its short duration, dominates the carbon emission (mostly in the form of CO2) and the production of light absorption and EC. Higher and more variable emission factors for CO, THC, and PM are found during the smoldering phase, especially for fuels containing substantial moisture. Organic carbon (OC) and EC mass account for a majority (i.e., >60%) of PM mass; other important elements include potassium, chlorine, and sulfur. Thermal analysis separates the EC into subfractions based on analysis temperature demonstrating that high-temperature EC (EC2; at 700 C) varies from 1% to 70% of PM among biomass burns, compared to 75% in kerosene soot. Despite this, the conversion factor between EC and light absorption emissions is rather consistent across fuels and burns, ranging from 7.8 to 9.6 m2/gEC. Findings from this study should be considered in the development of PM and EC emission inventories for visibility and radiative forcing assessments. -------------------------------------------------------------------------------- Lateral and Longitudinal Variation of Hyporheic Exchange in a Piedmont Stream Pool Robert J. Ryan and Michel C. Boufadel* Department of Civil and Environmental Engineering, Temple University, 1947 North 12th Street, Philadelphia, Pennsylvania 19122 Received for review July 6, 2006 Revised manuscript received March 24, 2007 Accepted April 2, 2007 Abstract: A conservative solute tracer experiment was conducted in Indian Creek, a small urban stream in Philadelphia, PA, to investigate the role of subsurface properties on the exchange between streamwater and the hyporheic zone (subsurface surrounding the stream). Sodium bromide (NaBr) was used as a conservative tracer, and it was monitored in the surface water and in the bed sediments of a 15 m long pool. Subsurface sampling occurred at 12 locations in the upper layer sediments (extending from 7.5 to 10 cm below the streambed) and 13 locations in the lower layer sediments (extending from 10 to 12.5 cm below the streambed). The hydraulic conductivity (K) of the upper bed sediments and the lower bed sediments was measured in situ. Several locations within the streambed exhibited an increase in tracer concentration with depth, suggesting the presence of horizontal flow paths within this small pool. Over the entire pool, the influence of K heterogeneity on hyporheic exchange was masked by the groundwater head gradient and the morphology of the stream. Together, the groundwater head gradient and stream morphology induced a generally high tracer concentration and fast hyporheic exchange on the left side and center of the channel and low concentrations and slower exchange on the right side. Although the reach-scale effects on the surface water concentration were small, groundwater greatly influenced the local-scale hyporheic exchange in the pool. Understanding how physical stream characteristics control the location and extent of hyporheic exchange pathways will lead to a better understanding of biogeochemical cycling of nutrients and contaminants. -------------------------------------------------------------------------------- |
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Environmental Applications of Chemically Pure Natural Ferrihydrite Jan Filip, Radek Zboril,* Oldrich Schneeweiss,# Josef Zeman, Miroslav Cernik, Petr Kvapil, and Michal Otyepka Centre for Nanomaterial Research, Palacky University, Svobody 26, 771 46 Olomouc, Czech Republic, Institute of Geological Sciences, Masaryk University, Kotlk 2, 611 37 Brno, Czech Republic, Department of Physical Chemistry, Palacky University, Svobody 26, 771 46 Olomouc, Czech Republic, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, ikova 22, 616 62 Brno, Czech Republic, and Technical University of Liberec, Research Center ARTEC, Hlkova 6, 461 17 Liberec, Czech Republic Received for review September 27, 2006 Revised manuscript received March 16, 2007 Accepted April 2, 2007 Abstract: Fresh precipitates, deposited from seepage waters of complex-ore mine-tailing impoundment at Zlaté Hory, Czech Republic, were characterized by means of X-ray diffraction, transmission electron microscopy, low temperature and in-field Mössbauer spectroscopy, and Brunauer-Emmett-Teller surface area measurements. The prevailing phases (~96 wt %) found in precipitates are poorly crystalline, 2-6 nm sized two-line ferrihydrite, forming globular aggregates of about 150 nm in diameter, rimmed by acicular irregular nanocrystals of goethite. These nanocrystalline ferrihydrite-goethite precipitates are of a relatively high chemical purity (~3% SiO2, Zn ~ 1300 ppm, trace and rare earth elements <100 ppm) and thus applicable in various nanotechnologies. With a surface area of 270 m2 g-1, precipitate possesses a high catalytic activity in the decomposition of hydrogen peroxide, which is comparable with that found for commercially accessible FeO(OH) catalyst. Another superior aspect of such natural nanoparticles presents a cheap and suitable precursor for a thermally induced solid-state synthesis of the stable core-shell -Fe-FeO nanoparticles that are well applicable in reductive technologies of groundwater treatment. Just the possibility of using the undesirable waste contaminating the environment in further environmental technologies is the key practical benefit discussed in this paper. -------------------------------------------------------------------------------- Organocuprate Conjugate Addition: The Square-Planar "CuIII" Intermediate Haipeng Hu and James P. Snyder* Department of Chemistry, Emory University, Atlanta, Georgia 30322 jsnyder@emory.edu Received October 20, 2006 Abstract: Rapid-injection NMR experiments with 2-cyclohexenone, TMSCl, and Me2CuLiLiCN by the Bertz and Ogle team (Bertz, S. H.; Cope, S.; Murphy, M.; Ogle, C. A.; Taylor, B. J. J. Am. Chem. Soc. 2007, 129, ASAP) have led to the observation of a new product-forming conjugate addition intermediate characterized by 1H and 13C NMR at -100 C. By employing conformational analysis, density functional theory (DFT) optimization, and prediction of NMR observables ( (TMS), 2J), the structure of the observed species is confirmed to be the elusive and long sought tetracoordinate square-planar "Cu(III) intermediate". Additional calculations suggest that symmetrical or unsymmetrical tetraalkyl analogues ([R4Cu]-1) are inherently more stable than the CN analogues ([R3CuCN]-1) and may be isolable. -------------------------------------------------------------------------------- Influence of Preparation Method on Morphology and Photocatalysis Activity of Nanostructured TiO2 Xin Jiang* and Ting Wang College of Material and Chemical Engineering, Zhejiang University, Hangzhou 310027, China Received for review January 15, 2007 Revised manuscript received March 21, 2007 Accepted April 3, 2007 Abstract: Supported TiO2 photocatalysts on aerosol silica were prepared by adsorption phase reaction technique (APRT) and impregnation method (IMP) under different water concentrations. Energy dispersive X-ray microanalysis indicated that Ti concentration in samples prepared by both methods increased with the content of water rising. There was a sharp increase in Ti content curve of APRT samples, while Ti concentration of IMP samples changed slowly. The grain size of TiO2 by APRT was below 6 nm and TiO2 particles dispersed uniformly on surface of silica. But the size of TiO2 by IMP was larger than 20 nm and the number of large particles increased rapidly when water concentration increased. The photocatalysis activity of as-prepared catalysts was characterized by methyl-orange photodegradation. The results showed that APRT photocatalysts had higher photocatalysis activity than IMP photocatalysts. Ti concentration and TiO2 crystalline form were two factors which affected photocatalysis activity the most. The grain size of TiO2 had little influence on photocatalysis activity, which might be counteracted by the decrease of anastase TiO2. -------------------------------------------------------------------------------- Process for Recycling Waste Aluminum with Generation of High-Pressure Hydrogen Takehito Hiraki, Satoru Yamauchi, Masayasu Iida, Hiroshi Uesugi, and Tomohiro Akiyama Center for Advanced Research of Energy Conversion Materials, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan, ITEC Co., Ltd., Kannanbechou 4 132, Sakai 590-0984, Japan, and Waseda University, Wasedatsurumaki-cho 513, Shinjuku-ku, Tokyo 162-0041, Japan Received for review December 5, 2006 Revised manuscript received March 19, 2007 Accepted March 30, 2007 Abstract: An innovative environmentlly friendly hydrolysis process for recycling waste aluminum with the generation of high-pressure hydrogen has been proposed and experimentally validated. The effect of the concentration of sodium hydroxide solution on hydrogen generation rate was the main focus of the study. In the experiments, distilled water and aluminum powder were placed in the pressure-resistance reactor made of Hastelloy, and was compressed to a desired constant water pressure using a liquid pump. The sodium hydroxide solution was supplied by liquid pump with different concentrations (from 1.0 to 5.0 mol/dm3) at a constant flow rate into the reactor by replacing the distilled water, and the rate of hydrogen generated was measured simultaneously. The liquid temperature in the reactor increased due to the exothermic reaction given by Al + OH- + 3H2O = 1.5H2 + Al(OH)4- + 415.6 kJ. Therefore, a high-pressure hydrogen was generated at room temperature by mixing waste aluminum and sodium hydroxide solution. As the hydrogen compressor used in this process consumes less energy than the conventional one, the generation of hydrogen having a pressure of almost 30 MPa was experimentally validated together with Al(OH)3, a useful byproduct. -------------------------------------------------------------------------------- Larval Exposure to 4-Nonylphenol and 17-Estradiol Affects Physiological and Behavioral Development of Seawater Adaptation in Atlantic Salmon Smolts Darren T. Lerner,* Björn Thrandur Björnsson, and Stephen D. McCormick Organismic and Evolutionary Biology, University of Massachusetts, Amherst, Massachusetts 01003, Conte Anadromous Fish Research Center, U.S. Geological Survey, PO Box 796-1 Migratory Way, Turners Falls, Massachusetts 01376, and Fish Endocrinology Laboratory, Department of Zoology/Zoophysiology, Göteborg University, Göteborg, Sweden Received for review January 25, 2007 Revised manuscript received April 9, 2007 Accepted April 17, 2007 Abstract: Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 g L-1 NP (NP-L or NP-H, respectively), 2 g L-1 17-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K+-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long term, "organizational" effects on life-history events in salmonids. -------------------------------------------------------------------------------- |
9楼2007-05-17 22:18:25
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HCB, p,p'-DDE and PCB Ontogenetic Transfer and Magnification in Bluefin Tuna (Thunnus thynnus) from the Mediterranean Sea Simonetta Corsolini,* Gianluca Sarà, Nicoletta Borghesi, and Silvano Focardi G. Sarfatti Department of Environmental Sciences, University of Siena, via P.A. Mattioli, 4, I-53100 Siena, Italy, and Animal Biology Department, University of Palermo, via Archirafi, 18, I-90123 Palermo, Italy Received for review October 11, 2006 Revised manuscript received March 31, 2007 Accepted April 8, 2007 Abstract: The bluefin tuna, Thunnus thynnus (Linnaeus 1758), is biologically and economically important in the Atlantic-Mediterranean ecosystems. Bluefin tuna feed on diverse food items depending on their age, thus they occupy different trophic levels during their lifespan. Hexachlorobenzene (HCB), p,p'-DDE and polychlorinated biphenyls (PCBs) are well-known persistent organic pollutants (POPs) in the Mediterranean basin. The relationship between stable isotopes of nitrogen (N) and the POP residue levels in tissues has recently increased knowledge on the link between the trophic levels and the contaminant accumulation. Trophic levels were estimated by using 15N/14N ratio (15N) and HCB, p,p'-DDE, and forty-three PCBs were quantified in bluefin tuna from the southern Tyrrhenian Sea. Results showed that changes in PCB and p,p'-DDE concentrations were a function of size and trophic level, while no correlations were observed for HCB. Apart from HCB and PCB nos. 101, 207, 95, 158, and 60 + 56, which did not show any significant increase per trophic level, the other PCBs and the p,p'-DDE increased significantly. The ontogenetic magnification factor of PCBs was 6.6 ± 0.5, which was significantly (12 times) higher (p < 0.05) than the values found for p,p'-DDE (1.4) and HCB (1.4). -------------------------------------------------------------------------------- Removal of Polycyclic Aromatic Hydrocarbons from Contaminated Soil by Aqueous DNA Solution Ronald R. Navarro, Hiroyasu Ichikawa, Yosuke Iimura, and Kenji Tatsumi* National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569, Japan Received for review October 13, 2006 Revised manuscript received February 9, 2007 Accepted March 26, 2007 Abstract: An aqueous DNA solution was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from a spiked soil. Solubilities of 0.56, 11.78, and 11.24 mg L-1 for anthracene, phenanthrene, and pyrene, respectively, were achieved after 1 day equilibration in 1% DNA. Using a spiked soil that contained 72 mg kg-1 anthracene, 102 mg kg-1 phenanthrene, and 99 mg kg-1 pyrene, extractions of close to 88, 78, and 94%, respectively, were attained with 5% DNA at a 1:50 soil/extractant ratio. Maximum PAH dissolution occurred after 4-6 h. Comparative tests showed the main advantage of DNA over methyl-- and -cyclodextrins and Tween 80 for pyrene removal. An ionic strength of 0.1 M NaCl was found necessary for maximum PAH dissolution and extraction. The performance of hexane regenerated DNA also remained stable after three stages of recycling. These results show the huge potential of DNA as an aqueous washing agent for PAH-contaminated soil. -------------------------------------------------------------------------------- Copper(II) Binding to Dissolved Organic Matter Fractions in Municipal Solid Waste Incinerator Bottom Ash Leachate Susanna Olsson,* Joris W. J. van Schaik, Jon Petter Gustafsson, Dan Berggren Kleja, and Patrick A. W. van Hees Department of Land and Water Resources Engineering, KTH (Royal Institute of Technology), 100 44 Stockholm, Sweden, Department of Soil Sciences, Swedish University of Agricultural Sciences, Box 7014, 750 07 Uppsala, Sweden, and Man-Technology Environment Research Center, Department of Natural Science, Örebro University, 701 82 Örebro, Sweden Received for review December 13, 2006 Revised manuscript received March 26, 2007 Accepted April 2, 2007 Abstract: Information on Cu speciation in municipal solid waste incineration (MSWI) bottom ash leachate is needed for Cu leaching predictions and toxicity estimates. The complexation of Cu with dissolved organic matter (DOM) in leachates from a stored MSWI bottom ash was studied potentiometrically using a Cu-ion selective electrode. More than 95% of the copper was bound to DOM in the hydrophilic fraction of the leachate, indicating that the hydrophilic acids contribute to Cu complex formation. The hydrophilic acids constituted 58% of the dissolved organic carbon in the ash leachate. Comparisons between experimental results and speciation calculations with the NICA-Donnan model and the Stockholm humic model indicated differences between the ash DOM and the natural DOM for which the models have been calibrated. The ratio of carboxylic binding sites to phenolic binding sites was 2 times larger in ash DOM, and the Cu-binding affinity of the former was stronger than accounted for by the generic Cu-binding parameters. The Cu-binding affinity of the phenolic sites, on the other hand, was weaker. When these parameters were adjusted, a good description of the experimental data was obtained. -------------------------------------------------------------------------------- Stable Carbon Isotope Fractionation of Chloroethenes by Dehalorespiring Isolates Patrick K. H. Lee, Mark E. Conrad, and Lisa Alvarez-Cohen* Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, and Earth Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 Received for review November 20, 2006 Revised manuscript received March 5, 2007 Accepted March 28, 2007 Abstract: Stable carbon isotope fractionation during the reductive dechlorination of chloroethenes by two bacterial strains that dechlorinate to ethene, Dehalococcoides ethenogenes 195 and Dehalococcoides sp. strain BAV1 as well as Sulfurospirillum multivorans and Dehalobacter restrictus strain PER-K23, isolates that do not dechlorinate past DCE, are reported. Fractionation by a Dehalococcoides-containing enrichment culture is also measured for comparison to the isolates. All data adequately fit the Rayleigh model and results are presented as enrichment factors. For strain 195, the measured enrichment factors were -9.6 ± 0.4, -21.1 ± 1.8, and -5.8 ± 0.5 when degrading TCE, cDCE, and 1,1-DCE, respectively. Strain BAV1 exhibited enrichment factors of -16.9 ± 1.4, -8.4 ± 0.3, -21.4 ± 0.9, and -24.0 ± 2.0 for cDCE, 1,1-DCE, tDCE, and VC, respectively. The surprisingly large differences in enrichment factors caused by individual reductases (RDases) reducing different chloroethenes is likely the result of chemical structure differences among the chloroethenes. For TCE reduction, S. multivorans and D. restrictus strain PER-K23 exhibited enrichment factors of -16.4 ± 1.5 and -3.3 ± 0.3, respectively. While all of the organisms studied here utilize RDases that require corrinoid cofactors, the biotic TCE enrichment factors varied widely from those reported for the abiotic cobalamin-catalyzed reaction, indicating that additional factors affect the extent of fractionation in these biological systems. The enrichment factors measured for the Dehalococcoides-containing enrichment culture did not match well with those from any of the isolates, demonstrating the inherent difficulties in predicting fractionation factors of undefined communities. Although compound-specific isotope fractionation is a powerful tool for evaluating the progress of in situ bioremediation in the field, given the wide range of enrichment factors associated with functionally similar and phylogenetically diverse organisms, caution must be exercised when applying enrichment factors for the interpretation of dechlorination data. -------------------------------------------------------------------------------- |
3楼2007-05-11 23:02:11
4楼2007-05-12 13:18:15
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Modeling Atmospheric Vegetation Uptake of PBDEs Using Field Measurements Annick D. St-Amand, Paul M. Mayer, and Jules M. Blais* Department of Chemistry, University of Ottawa, 10 Marie-Curie, Ottawa, Ontario, K1N 6N5, and Department of Biology, University of Ottawa, 30 Marie-Curie, Ottawa, Ontario, K1N 6N5 Received for review October 12, 2006 Revised manuscript received March 8, 2007 Accepted April 4, 2007 Abstract: Polybrominated diphenyl ethers (PBDEs) are flame retardants used in a variety of consumables. Models indicate that air-vegetation exchange plays an important role in their global distribution. The present study surveyed PBDEs in spruce needles and air (gaseous and particulate-bound) over an annual cycle to model accumulation of PBDEs in vegetation. Air-particulate distributions revealed that penta and higher BDE congeners were mainly associated with particulates even in warmer temperatures, whereas for the tri- and tetra-BDE congeners, a significant temperature dependence was observed. Using measured vegetation and atmospheric concentrations from bud burst 2004 to June 2005, a modeling concept was developed to determine PBDE deposition velocities to vegetation. Particulate-bound deposition velocity was calculated to be 3.8 m/h. Net gaseous transfer velocities ranged from 2.4 to 62.2 m/h and correlated significantly with log KOA. These derived values were used to model PBDE accumulation by vegetation through time, and these agreed well with measured values. This study provides the necessary background for modeling PBDE transport between air and coniferous vegetation globally. -------------------------------------------------------------------------------- Mechanistic Studies of the Photocatalytic Degradation of Methyl Green: An Investigation of Products of the Decomposition Processes Chiing-Chang Chen* and Chung-Shin Lu Department of General Education, National Taichung Nursing College, Taichung 403, Taiwan, ROC Received for review October 14, 2006 Revised manuscript received March 20, 2007 Accepted April 3, 2007 Abstract: The methyl green (MG) dye dissolves into an alkaline solution when the pH value is too high (pH 9). The cationic MG dye molecules are converted into the colorless carbinol base (CB) and produce crystal violet (CV) dye and ethanol by hydroxide anion. Thirty-three intermediates of the process were separated, identified, and characterized by HPLC-ESI-MS technique in this study and their evolution during the photocatalytic reaction is presented. Moreover, the other intermediates formed in the photocatalytic degradation MG processes were separated and identified by HPLC-PDA technique. The results indicated that the N-de-methylated degradation of CV dye took place in a stepwise manner to yield N-de-methylated CV species, and the N-de-alkylated degradation of CB also took place in a stepwise manner to yield N-de-alkylated CB species generated during the processes. Moreover, the oxidative degradation of the CV dye (or CB) occurs to yield 4-(N,N-dimethylamino)phenol (DAP), 4-(N,N-dimethylamino)-4'-(N',N'-dimethylamino)benzophenone (DDBP) and their N-de-methylated products [or to yield 4-(N-ethyl-N,N-dimethyl)aminophenol (EDAP), DDBP, 4-(N-ethyl-N,N-dimethylamino)-4'-(N',N'-dimethylamino)benzophenone (EDDBP), DAP, and their N-de-alkylated products], which were found for the first time. A proposed degradation pathway of CV and CB is presented, involving mainly the N-de-alkylation and oxidation reaction. -------------------------------------------------------------------------------- Supercritical Preparation of a Highly Active S-Doped TiO2 Photocatalyst for Methylene Blue Mineralization Hexing Li,* Xinyu Zhang, Yuning Huo, and Jian Zhu Department of Chemistry, Shanghai Normal University, Shanghai 200234, P. R. China Received for review November 8, 2006 Revised manuscript received February 25, 2007 Accepted February 26, 2007 Abstract: Sulfur-modification of the TiO2 was achieved by treating the TiO2 precursor (xerogel) under supercritical conditions in CS2/ethanol fluid. Nuclear magnetic resonance, X-ray photoelectron spectroscopy and Fourier transform infrared spectra demonstrated that the TiO2 was modified by the S-species incorporated into the TiO2 network by forming S-Ti-O bonds rather than by the adsorbed CS2. During liquid-phase photocatalytic degradation of methylene blue (MB) under visible light irradiation (>420 nm), the as-prepared S-doped TiO2 exhibited much higher activity than the undoped TiO2 obtained via either supercritical treatment or direct calcinations and even the N-doped TiO2 obtained via supercritical treatment. The promoting effects of both the supercritical treatment and S-modification on the photocatalytic activity were discussed by considering the high surface, large porous channels, well crystallized anatase phase, excellent thermal stability, and strong absorbance for visible lights, corresponding to the high quantum efficiency. The maximum activity was obtained at 1.8% S/Ti molar ratio, nearly 8 times higher than that of the commercially available P25 TiO2. -------------------------------------------------------------------------------- Kinetic Gas-Water Transfer and Gas Accumulation in Porous Media during Pulsed Oxygen Sparging Gerd U. Balcke, Stefan Meenken, Carsten Hoefer, and Sascha E. Oswald* UFZ, Helmholtz Centre for Environmental Research, Department of Hydrogeology, Permoserstr. 15, 04318 Leipzig, Germany Received for review December 5, 2006 Revised manuscript received March 27, 2007 Accepted March 28, 2007 Abstract: Gas-water mass transfer and the transport of dissolved gases in variably saturated porous media are key processes for in-situ remediation by pulsed gas sparging. In this context, gas dissolution tests were conducted during pulsed oxygen gas injection into sand columns. The columns were recharged with anoxic water, effluents were analyzed for dissolved O2, and tracer tests were performed to detect accumulation of trapped gas. In a second series oxygen gas was blended with sulfur hexafluoride (SF6), and O2 and SF6 breakthrough curves were recorded. To interpret experimental results, a numerical model was applied that simulates multi-species kinetic mass transfer during gas dissolution. The model predicted breakthrough curves of dissolved gas species and delivered spatially resolved values for gas phase accumulation and composition, which are not directly accessible experimentally. It was shown how dissolved nitrogen accumulates increasingly in trapped gas phase and inhibits its complete dissolution, in case the pulsed gas injections were operated based on O2 breakthrough only. Accumulation of nitrogen also retarded dissolved oxygen transport and thus oxygen breakthrough. Experiments plus modeling demonstrated that SF6 measurements are highly sensitive to the gas dissolution processes, and provide a more sensitive criterion for determining gas injection frequencies during pulsed biosparging. -------------------------------------------------------------------------------- Accumulation, Whole-Body Depletion, and Debromination of Decabromodiphenyl Ether in Male Sprague-Dewley Rats Following Dietary Exposure Janice K. Huwe* and David J. Smith: Degradation of Methylene Blue by Three-Dimensionally Ordered Macroporous Titania Madhavi Srinivasan* and Tim White School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 Received for review January 22, 2007 Revised manuscript received March 20, 2007 Accepted March 30, 2007 Abstract: Accelerated photodegradation of methylene blue (MB) over three-dimensionally ordered macroporous (3DOM) titania (pore sizes: 0.5 and 1 m) is demonstrated. The catalysts were synthesized by colloidal crystal templating against polystyrene spheres using a metal alkoxide precursor. The 3DOM titania walls which are predominantly anatase (>98%) were decorated homogeneously with gold nanoparticles (5-7 nm) by pH-controlled precipitation of Au from HAuCl4 using sodium hydroxide. A combination of powder X-ray diffraction (XRD), analytical transmission electron microscopy (ATEM) and X-ray photoelectron spectroscopy (XPS) confirmed the deposition of Au(0) on the 3DOM titania macroporous walls. Photocatalytic activity was monitored by following the degradation of MB with activity benchmarked against commercial P25 (Degussa) and powder titania prepared by hydrolysis of titanium ethoxide. Macroporous 3DOM titania with pore diameter 0.5 m had the highest first-order rate constant of 0.042 min-1 for decomposition of MB, compared to 0.025 min-1 for P25 titania. Deposition of gold on the 3DOM titania surfaces decreased the reaction rate by covering the surface active sites. -------------------------------------------------------------------------------- |
5楼2007-05-12 22:06:48