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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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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
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Effect of Near-Wall Air Curtain on the Wall Deposition of Droplets in a Semidry Flue Gas Desulfurization Reactor Jie Zhang, Changfu You,* Changhe Chen, Haiying Qi, and Xuchang Xu Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China Received for review August 19, 2006 Revised manuscript received April 2, 2007 Accepted April 10, 2007 Abstract: The wall deposition of droplets is an important issue affecting the desulfurization efficiency and operating stability of semidry flue gas desulfurization (FGD) reactors. Various near-wall air velocities, near-wall air flow inlet heights, and spray characteristics were analyzed numerically to investigate their effect on the gas-liquid flow and droplet deposition characteristics. The analytical results show that the near-wall air curtain effectively reduces the wall deposition of droplets in the semidry FGD reactor. The droplet deposition ratio decreased rapidly with increasing near-wall air velocity due to the increased gas flow rates and the altered gas velocity distribution. The near-wall air flow inlet height had an optimum value due to the rapid decline of the near-wall air momentum along the reactor height. The optimum distance between the near-wall air inlet height and the droplet injection height was 1.2 times that of the droplet vertical movement distance before deposition based on the linear droplet movement. For commonly used spray characteristics in the semidry FGD process, i.e., droplet diameters of 50-150 m, spray angles of 10-70 and droplet initial velocities of 20-100 m/s, the droplet deposition ratio with the addition of the near-wall air curtain varied slightly with the droplet diameter and the spray angle but increased rapidly with the initial droplet velocity. Therefore, for the semidry FGD processes, the near-wall air curtain is an effective method to reduce the wall deposition of droplets for various droplet diameters and spray angles while the initial droplet velocity should be carefully controlled to reduce the wall deposition of droplets and improve the operating stability. -------------------------------------------------------------------------------- |
6楼2007-05-15 22:39:36
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ABAM, a Model for Bioaccumulation of POPs in Birds: Validation for Adult Herring Gulls and Their Eggs in Lake Ontario Ross J. Norstrom,* Thomas P. Clark, Michael Enright, Brian Leung, Ken G. Drouillard, and Colin R. Macdonald# National Wildlife Research Centre, Canadian Wildlife Service, Environment Canada, Carleton University, Raven Road, Ottawa, ON K1A 0H3, Canada, CMC Ecological Consulting, 1150 Golden Beach Road, Bracebridge, ON P1L 1W8, Canada, Dillon Consulting Limited, 235 Yorkland Boulevard, Suite 800, Toronto, ON M2J 4Y8, Canada, Department of Biology & the McGill School of Environment, 205 Docteur Penfield, McGill University, Montreal, QC H3A 1B1, Canada, Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON N9B 3P4, Canada, and Northern Environmental Consulting, Box 374, Pinawa, MB R0E 1L0, Canada Received for review September 15, 2006 Revised manuscript received April 1, 2007 Accepted April 5, 2007 Abstract: An Avian BioAccumulation Model (ABAM) of persistent organic pollutant (POP) uptake and elimination in adult life-stage of birds was validated by simulation of concentrations of DDE, dieldrin, mirex, and HCB in herring gull eggs in Lake Ontario for the years 1985, 1990, and 1992. These chemicals represented a range of whole-body half-lives of 82-265 days in the gull. Dietary intake of POPs by a female gull was simulated by a dynamic bioenergetics model which included dependence on temperature, photoperiod, egg production, and feeding chicks. Concentrations in the two main prey fish of the gull in Lake Ontario were used for POP exposure. Clearance from the female was based on a two compartment toxicokinetic model. Egg concentrations were estimated from egg/whole body female concentration ratios. Simulated concentrations were compared to measured concentrations in gull eggs from 4 different colonies in the northern part of Lake Ontario. Simulations using a diet of 81% fish and 19% uncontaminated food resulted in the best fit with least variance among predicted and measured data. The mean ratio of predicted to measured concentrations in eggs was 1.0 ± 0.27 among chemicals, years, and colonies for this exposure scenario. This result was in excellent agreement with field assessments of herring gull diet composition in Lake Ontario of 80-82% fish. The ability to perform accurate a priori simulations for the range of test conditions employed in the validation constituted a rigorous test of the soundness of the model's structure and parameterization. With species-specific adjustments, ABAM can be regarded as a general model for lipophilic POPs bioaccumulation in birds. -------------------------------------------------------------------------------- A New Generation of Sludge-Based Adsorbents for H2S Abatement at Room Temperature Anna Ros, M. Angeles Lillo-Ródenas, Carla Canals-Batlle, Enrique Fuente, Miguel A. Montes-Morn, María J. Martin,* and Angel Linares-Solano Laboratori d'Enginyeria Química i Ambiental (LEQUIA), Institut de Medi Ambient, Facultat de Ciències, Universitat de Girona, E-17071 Girona, Spain, Grupo de Materiales Carbonosos y Medioambiente (MCMA), Departamento de Química Inorgnica, Universidad de Alicante, Apartado 99, E-03080 Alicante, Spain, and Instituto Nacional del Carbón, CSIC, Apartado 73, E-33080 Oviedo, Spain Received for review October 3, 2006 Revised manuscript received January 16, 2007 Accepted April 4, 2007 Abstract: The present paper discusses H2S removal by a new generation of sewage-sludge-derived materials which are characterized by their outstanding textural properties when compared to previous materials obtained by pyrolysis and/or activation of similar precursors. Alkaline hydroxide activation was used to prepare adsorbents/catalysts covering a wide range of porosities (SBET values from 10 to 1300 m2 g-1). Our results outline that textural properties are important for H2S abatement. However, not only highly porous sorbents, but also a high metallic content and a basic pH of these materials are required to achieve good performances. Proper combinations of textural properties and alkalinity render superior performances with retention values (x/M) as high as 456 mg of H2S removed per g of material. These retention capacities outperform previously published data for sewage-sludge derived materials and those achieved with commercial materials (including some activated carbons). Sulfur titration shows that most H2S is removed in the form of elemental sulfur, especially in the sewage/NaOH materials. -------------------------------------------------------------------------------- Screening Method for Ecotoxicological Hazard Assessment of 42 Pharmaceuticals Considering Human Metabolism and Excretory Routes Judit Lienert,* Karin Güdel, and Beate I. Escher Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland Received for review November 21, 2006 Revised manuscript received April 5, 2007 Accepted April 9, 2007 Abstract: We assessed the ecotoxicological hazard potential of 42 pharmaceuticals from 22 therapeutic groups, including metabolites formed in humans. We treated each parent drug and its metabolites as a mixture of similarly acting compounds. If physicochemical or effect literature data were missing, we estimated these with quantitative structure-activity relationships (QSAR). Additionally, we estimated micropollutant removal efficiency of urine source separation using pharmaceutical information. On average, 50% of a parent drug was metabolized, and 70% was excreted with urine, albeit with large variations among drugs. Metabolism reduced the toxic potential of all but eight drugs. The subsequently modeled risk quotient was mostly below the threshold of one. However, ibuprofen and its metabolites in a mixture could pose an ecotoxicologal risk; and possibly also acetylsalicylic acid, bezafibrate, carbamazepine, diclofenac, fenofibrate, and paracetamol. Lipophilicity and sale quantities of parent drugs alone were insufficient to estimate their ecotoxicological risk. Urine separation could decrease the ecotoxicological risk of some, but not all drugs. The estimated risk quotients were equal in urine and feces, again with large variations among compounds. Because of scientific limitations of the model and inconsistent literature data the results are somewhat uncertain. However, this new approach allows first tier screening of single drugs, thus supporting decision-making. -------------------------------------------------------------------------------- Long-Term Stability of Organic Carbon-Stimulated Chromate Reduction in Contaminated Soils and Its Relation to Manganese Redox Status Tetsu K. Tokunaga,* Jiamin Wan, Antonio Lanzirotti, Steve R. Sutton, Matthew Newville, and William Rao Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, University of Chicago, 5801 South Ellis Avenue, Chicago, Illinois 60637, and Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina 29802 Received for review December 4, 2006 Revised manuscript received March 13, 2007 Accepted April 13, 2007 Abstract: In situ reduction of toxic Cr(VI) to less hazardous Cr(III) is becoming a popular strategy for remediating contaminated soils. However, the long-term stability of reduced Cr remains to be understood, especially given the common presence of Mn(III,IV) oxides that re-oxidize Cr(III). This 4.6 year laboratory study tracked Cr and Mn redox transformations in soils contaminated with Cr(VI), which were then treated with different amounts of organic carbon (OC). Changes in Cr and Mn oxidation states within soils were directly and nondestructively measured using micro-X-ray absorption near-edge structure spectroscopy. Chromate reduction was roughly first-order, and the extent of reduction was enhanced with higher OC additions. However, significant Cr(III) re-oxidation occurred in soils exposed to the highest Cr(VI) concentrations (2560 mg kg-1). Transient Cr(III) re-oxidation up to 420 mg kg-1 was measured at 1.1 years after OC treatment, followed by further reduction. Chromate concentrations increased by 220 mg kg-1 at the end of the study (4.6 years) in one soil. The causal role that the Mn oxidation state had in re-oxidizing Cr was supported by trends in Mn K-edge energies. These results provide strong evidence for long-term dependence of soil Cr oxidation states on balances between OC availability and Mn redox status. -------------------------------------------------------------------------------- Ni Uptake by a Green Alga. 1. Validation of Equilibrium Models for Complexation Effects Isabelle A. M. Worms, Nalini Parthasarathy, and Kevin J. Wilkinson* CABE (Analytical and Biophysical Environmental Chemistry), University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland, and Department of Chemistry, University of Montreal, P.O. Box 6128, Succursale Centre-ville, Montreal, Canada H3C 3J7 Received for review December 20, 2006 Revised manuscript received March 2, 2007 Accepted March 12, 2007 Abstract: Short term (<60 min) internalization fluxes (Jint) by the green alga Chlamydomonas reinhardtii were measured in the presence of a variety of ligands forming hydrophilic (citric, diglycolic, or nitrilotriacetic acids), amphiphilic (Suwannee River fulvic and humic acids), and hydrophobic (oxine, diethyldithiocarbamate) Ni complexes. Free nickel concentrations, ranging from 10-10 to 10-3 M, were evaluated by thermodynamic modeling and by a resin exchange technique. Ni internalization appeared to occur via a single transport site that was characterized by a conditional stability constant (pH 6.0, I = 10-2 M) of 105.1 M-1. In the presence of humic substances, Ni uptake could be quantitatively predicted on the basis of Ni2+ concentrations for two algae: C. reinhardtii and Chlorella kesslerii. In the presence of the hydrophobic ligands, an increase in permeability was observed due to the formation of neutral, lipophilic complexes. -------------------------------------------------------------------------------- Chemical Speciation of Dissolved Cu, Ni, and Co in a Contaminated Estuary in Southwest Spain and Its Influence on Plankton Communities Charlotte B. Braungardt, Eric P. Achterberg,* Martha Gledhill, Malcolm Nimmo, Francoise Elbaz-Poulichet, Antonio Cruzado, and Zoila Velasquez University of Plymouth, School of Earth, Ocean, and Environmental Science, Plymouth PL4 8AA, United Kingdom, University of Southampton, National Oceanography Centre Southampton, School of Ocean and Earth Science, European Way, SO14 3ZH Southampton, United Kingdom, University of Montpellier I and II, CNRS-IRD, UMR Hydrosciences-CCMSE, 34095 Montpellier Cedex 5, France, and Centro de Estudios Avanzados de Blanes (CEAB), Camí de Santa Brbara, E-17300 Blanes, Spain Received for review December 21, 2006 Revised manuscript received March 20, 2007 Accepted April 2, 2007 Abstract: Four surveys of the Huelva Estuary in southwest Spain and its sources, the Tinto and the Odiel Rivers, were carried out between 1996 and 1998. The surveys investigated the impact of metalliferous mining of sulfide-rich ores in the catchment area on metal speciation, metal concentrations in a macrophyte, and phytoplankton diversity and abundance. Chemical speciation measurements in the lower Tinto Estuary showed that metals were predominantly electrochemically labile (>99% of total dissolved Cu, Co, and Ni at 10 M Cu, 424 nM Co, and 500 nM Ni, S = 28). Concentrations of Cu complexing ligands and free cupric ions [Cu2+] in the Gulf of Cdiz ranged between 5.3 and 38 nM and 0.2-7.9 pM, respectively, with conditional stability constants of the ligands of log K'CuL = 11.7-12.6. At enhanced dissolved Cu concentrations in the lower Huelva Estuary, Cu complexing ligands were saturated with Cu, resulting in nanomolar [Cu2+], which increased upstream. Metal tissue concentrations of the macrophyte Blindingia marginata were high, and a clear relationship between dissolved labile Cu and macrophyte tissue Cu concentrations was observed. A low biodiversity was observed in the Huelva system (Shannon-Wiener indices (H) typically <0.2). Nevertheless, the maximum biomass was observed in the lower Tinto Estuary, which showed high labile metal and nutrient concentrations and a low biodiversity (H < 0.02), thereby suggesting adaptation through evolutionary processes of the phytoplankton community to the harsh conditions. -------------------------------------------------------------------------------- Ni Uptake by a Green Alga. 2. Validation of Equilibrium Models for Competition Effects Isabelle A. M. Worms and Kevin J. Wilkinson* CABE (Analytical and Biophysical Environmental Chemistry), University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland, and Department of Chemistry, University of Montreal, P.O. Box 6128, Succursale Centre-ville, Montreal, Canada H3C 3J7 Received for review December 20, 2006 Revised manuscript received March 2, 2007 Accepted March 12, 2007 Abstract: It is generally admitted that the presence of major cations and H+ can attenuate trace metal uptake. Recent models such as the biotic ligand model (BLM) aim to quantify and predict this effect by determining stability constants for each of the major competitors for any given interaction of a trace metal with a biological organism. In this study, short-term Ni internalization fluxes (Jint) were used to quantitatively assess the binding of H+, Mg2+, Ca2+ (KH-Rs, KMg-Rs, KCa-Rs), and trace metals to transport sites (Rs) leading to Ni biouptake by Chlamydomonas reinhardtii. H+ and Mg2+ are shown to compete directly for the entry of Ni with affinity constants that are of the same order of magnitude (KMg-Rs = 105.1 M-1; KH-Rs = 105.3 M-1) as that measured for Ni (KNi-Rs = 105.1 M-1). The Ni internalization fluxes were also strongly linked to the Mg cell status. In contrast, the role of Ca2+ could not be explained by a simple competitive equilibrium with the Ni transport sites. Aluminum (KAl-Rs = 108 M-1), Zn (KZn-Rs = 106.5 M-1), and Cu (KCu-Rs = 106.6 M-1) were all shown to compete strongly with Ni for uptake. In addition to the determination of uptake constants, these studies provide insight into the transport mechanisms of Ni by the green alga, C. reinhardtii. -------------------------------------------------------------------------------- |
7楼2007-05-16 21:49:25
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A Novel Test for Measuring and Managing Potential Phosphorus Loss from Dairy Cattle Feces Zhengxia Dou,* Charles F. Ramberg, Jr., Lydie Chapuis-Lardy, John D. Toth, Yu Wang, Robert J. Munson, Zhiguo Wu, Larry E. Chase, Richard A. Kohn, Katharine F. Knowlton, and James D. Ferguson Section of Animal Production Systems, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, Pennsylvania 19348, Institut de Recherche pour le Développement, 213 Rue La Fayette, 75 480 Paris, Cedex 10 France, Cornell University, Ithaca, New York 14853, University of Maryland, College Park, Maryland 20742, and Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 Received for review December 20, 2006 Revised manuscript received March 18, 2007 Accepted April 11, 2007 Abstract: Pollution of waters resulting from phosphorus (P) runoff from agricultural land receiving long-term manure application is one of the most serious threats to water quality in many regions of the world. Of various approaches to alleviate the problem, reducing P surplus on animal farms through optimizing P intake and minimizing P excretion in manure offers a great opportunity. Here, we present a fecal P test method that has the potential to identify over-feeding of P in dairy cattle. Previous research has suggested that water-extractable P in dairy cow feces closely reflects dietary P changes and may indicate the animal's P status (adequate vs excessive). However, the notion was somewhat confounded when a subsequent study found other factors (pH and Ca content as well as sample handling method) also affecting P extractability in water. In the present work, we hypothesize that the impact of those factors on P extractability can be overcome by selecting dilute acid solutions to replace deionized water as the extractant. Using samples from 25 commercial dairy farms, we tested an array of acid solutions (including HCl, citric acid, and acetic acid) and found that 0.1% HCl is the most suitable extractant. Inorganic P (Pi) released in 0.1% HCl closely reflected dietary P changes among the farms (R2 = 0.69) and was independent of pH, Ca, or sample handling method. Knowledge of P metabolism and partitioning in dairy cows and our experimental data suggest that excess P intake by the animal leads to greater amounts of bioavailable but unabsorbed P, which is excreted in feces. Its relative magnitude may be estimated by measuring Pi extractable in 0.1% HCl. This novel and simple fecal P test could potentially be used as an indicator of the animal's P supply utilization status and thus serve as a screening tool for the presence of P over-feeding on dairy farms. -------------------------------------------------------------------------------- SO2 Retention by Reactivated CaO-Based Sorbent from Multiple CO2 Capture Cycles Vasilije Manovic and Edward J. Anthony* CANMET Energy Technology Centre-Ottawa, Natural Resources Canada, 1 Haanel Drive, Ottawa, Ontario, Canada K1A 1M1 Received for review December 12, 2006 Revised manuscript received March 22, 2007 Accepted April 4, 2007 Abstract: This paper examines the reactivation of spent sorbent, produced from multiple CO2 capture cycles, for use in SO2 capture. CaO-based sorbent samples were obtained from Kelly Rock limestone using three particle size ranges, each containing different impurities levels. Using a thermogravimetric analyzer (TGA), the sulfation behavior of partially sulfated and unsulfated samples obtained after multiple calcination-carbonation cycles in a tube furnace (TF), following steam reactivation in a pressurized reactor, is examined. In addition, samples calcined/sintered under different conditions after hydration are also examined. The results show that suitably treated spent sorbent has better sulfation characteristics than that of the original sorbent. Thus for example, after 2 h sulfation, >80% of the CaO was sulfated. In addition, the sorbent showed significant activity even after 4 h when >95% CaO was sulfated. The results were confirmed by X-ray diffraction (XRD) analysis, which showed that, by the end of the sulfation process, samples contained CaSO4 with only traces of unreacted CaO. The superior behavior of spent reactivated sorbent appears to be due to swelling of the sorbent particles during steam hydration. This enables the development of a more suitable pore surface area and pore volume distribution for sulfation, and this has been confirmed by N2 adsorption-desorption isotherms and the Barrett-Joyner-Halenda (BJH) method. The surface area morphology of sorbent after reactivation was examined by scanning electron microscopy (SEM). Ca(OH)2 crystals were seen, which displayed their regular shape, and their elemental composition was confirmed by energy-dispersive X-ray (EDX) analysis. The improved characteristics of spent reactivated sorbent in comparison to the original and to the sorbent calcined under different conditions and hydrated indicate the beneficial effect of CO2 cycles on sorbent reactivation and subsequent sulfation. These results allow us to propose a new process for the use of CaO-based sorbent in fluidized bed combustion (FBC) systems, which incorporates CO2 capture, sorbent reactivation, and SO2 retention. -------------------------------------------------------------------------------- Hydroxylated Metabolites of - and -Hexachlorocyclohexane: Bacterial Formation, Stereochemical Configuration, and Occurrence in Groundwater at a Former Production Site Vishakha Raina, Andrea Hauser, Hans Rudolf Buser,* Daniel Rentsch, Poonam Sharma, Rup Lal, Christof Holliger, Thomas Poiger, Markus D. Müller, and Hans-Peter E. Kohler Environmental Microbiology, Swiss Federal Institute for Aquatic Science and Technology (Eawag), CH-8600 Dübendorf, Switzerland, Agroscope Changins-Wädenswil, Research Station ACW, CH-8820 Wädenswil, Switzerland, Laboratory for Functional Polymers, EMPA, Swiss Federal Laboratories for Materials Testing and Research, CH-8600 Dübendorf, Switzerland, Department of Zoology, University of Delhi, Delhi-110007, India, and EPFL, ENAC-ISTE, Laboratory of Environmental Biotechnology, CH-1015, Lausanne, Switzerland Received for review December 7, 2006 Revised manuscript received April 5, 2007 Accepted April 9, 2007 Abstract: Although the use of hexachlorocyclohexane (HCH), one of the most popular insecticides after the Second World War, has been discontinued in many countries, problems remain from former production and waste sites. Despite the widespread occurrence of HCHs, the environmental fate of these compounds is not fully understood. In particular, environmental metabolites of the more persistent -HCH and -HCH have not been fully identified. Such knowledge, however, is important to follow degradation and environmental fate of the HCHs. In the present study, several hydroxy metabolites that formed during incubation of - and -HCH with the common soil microorganism Sphingobium indicum B90A were isolated, characterized, and stereochemically identified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). The metabolites were identified as isomeric pentachlorocyclohexanols (B1, D1) and tetrachlorocyclohexane-1,4-diols (B2, D2); -HCH additionally formed a tetrachloro-2-cyclohexen-1-ol (D3) and a trichloro-2-cyclohexene-1,4-diol (D4), most likely by hydroxylation of -pentachlorocyclohexene (-PCCH), initially formed by dehydrochlorination. The dehydrochlorinase LinA was responsible for conversion of -HCH into -PCCH, and the haloalkane dehalogenase LinB was responsible for the transformation of -HCH and -HCH into B1 and D1, respectively, and subsequently into B2 and D2, respectively. LinB was also responsible for transforming -PCCH into D3 and subsequently into D4. These hydroxylations proceeded in accordance with SN2 type reactions with initial substitution of equatorial Cls and formation of axially hydroxylated stereoisomers. The apparently high reactivity of equatorial Cls in - and -HCH toward initial hydroxylation by LinB of Sphingobium indicum B90A is remarkable when considering the otherwise usually higher reactivity of axial Cls. Several of these metabolites were detected in groundwater from a former HCH production site in Switzerland. Their presence indicates that these reactions proceed under natural environmental conditions and that the metabolites are of environmental relevance. -------------------------------------------------------------------------------- |
8楼2007-05-16 21:51:22
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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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Estimation of Atmospheric Emissions of Six Semivolatile Polycyclic Aromatic Hydrocarbons in Southern Canada and the United States by Use of an Emissions Processing System Elisabeth Galarneau,* Paul A. Makar, Mourad Sassi, and Miriam L. Diamond Air Quality Research Division, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, M3H 5T4, Canada, National Prediction Operations, Environment Canada, 2121 Route Trans-Canadienne, Dorval, Quebec, H9P 1J3, Canada, and Department of Geography, University of Toronto, 45 St. George Street, Toronto, Ontario, M5S 3G3, Canada Received for review September 26, 2006 Revised manuscript received March 30, 2007 Accepted April 2, 2007 Abstract: Polycyclic aromatic hydrocarbons (PAHs) are toxic compounds that are ubiquitous in the atmospheric environ ment. The input for an emissions processing system that was originally configured for the study of criteria air pollutants was updated to calculate emissions of six semivolatile PAHs. The goal of the work was to produce emissions estimates with the spatial and temporal resolution needed to serve as input to a regional air quality model for southern Canada and the U.S. Such modeling is helpful in determining reductions in PAH emissions that may be necessary to protect human and ecosystem health. The total annual emission of the six PAHs (6PAH) for both countries was estimated at 18 273 Mg/year. A total of 90% of these emissions arise from U.S. sources. The top six source types account for 73% of emissions and are related to metal production, open burning, incineration, and forest fires. The emission factors used in this study were derived from published compilations. Although this approach has the advantage of quality control during the compilation process, some compilations include factors from older studies that may overestimate emissions since they do not account for recent improvements in emission control technology. When compared to estimates published in the National Emissions Inventory (NEI) for 2002, the U.S. emissions in this study are higher by a factor of 4 (16 424 vs 4102 Mg/year). The cause of this difference has been investigated, and much of it is likely due to our use of data unavailable in the 2002 NEI but inferred here on the basis of the PAH emissions literature. Augmenting the 2002 NEI with this additional information would bring its reported annual emissions to 8213 Mg/year, which is within a factor of 2 of the estimates herein. The results presented for southern Canada are the first published values for all known PAH sources in that country. -------------------------------------------------------------------------------- Mathematical Model Developed for Environmental Samples: Prediction of GC/MS Dioxin TEQ from XDS-CALUX Bioassay Data David J. Brown, Jean Orelien, John D. Gordon, Andrew C. Chu, Michael D. Chu, Masafumi Nakamura, Hiroshi Handa, Fujio Kayama,# Michael S. Denison, and George C. Clark* Xenobiotic Detection Systems, 1601 East Geer Street, Suite S, Durham, North Carolina 27704, Marietta College, 215 5th Street, Marietta, Ohio 45750, SciMetrika, LLC, 2 Davis Drive, Research Triangle Park, North Carolina 27709, Analytical Perspectives, 2714 Exchange Drive, Wilmington, North Carolina 28405, Hiyoshi Corporation, 908 Kitanosho-cho, Omihachiman, Shiga 523-8555 Japan, Department of Environmental Medicine, Center for Community Medicine, Jichi Medical University, Tochigi 329-0498, Japan, and Department of Environmental Toxicology, Meyer Hall, University of California-Davis, Davis, California 95616 Received for review October 30, 2006 Revised manuscript received February 16, 2007 Accepted March 13, 2007 Abstract: Remediation of hazardous waste sites requires efficient and cost-effective methods to assess the extent of contamination by toxic substances including dioxin-like chemicals. Traditionally, dioxin-like contamination has been assessed by gas chromatography/high-resolution mass spectrometry (GC/MS) analysis for specific polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyl congeners. Toxic equivalency factors for these congeners are then used to estimate the overall dioxin toxic equivalency (TEQ) of complex mixtures found in samples. The XDS-CALUX bioassay estimates contamination by dioxin-like chemicals in a sample extract by measuring expression of a sensitive reporter gene in genetically engineered cells. The output of the XDS-CALUX assay is a CALUX-TEQ value, calibrated based on TCDD standards. Soil samples taken from a variety of hazardous waste sites were measured using the XDS-CALUX bioassay and GC/MS. TEQ and CALUX-TEQ from these methods were compared, and a mathematical model was developed describing the relationship between these two data sets: log(TEQ) = 0.654 × log(CALUX-TEQ) + 0.058(log(CALUX-TEQ))2. Applying this equation to these samples showed that predicted and GC/MS measured TEQ values strongly correlate (R2 = 0.876) and that TEQ values predicted from CALUX-TEQ were on average nearly identical to the GC/MS-TEQ. The ability of XDS-CALUX bioassay data to predict GC/MS-derived TEQ data should make this procedure useful in risk assessment and management decisions. -------------------------------------------------------------------------------- Electrochemistry of Free Chlorine and Monochloramine and its Relevance to the Presence of Pb in Drinking Water Vishnu V. Rajasekharan, Brandi N. Clark, Sansanee Boonsalee, and Jay A. Switzer* Department of Chemistry and Graduate Center for Materials Research, University of Missouri-Rolla, Rolla, Missouri 65409-117 Received for review December 8, 2006 Revised manuscript received March 9, 2007 Accepted April 9, 2007 Abstract: The commonly used disinfectants in drinking water are free chlorine (in the form of HOCl/OCl-) and monochloramine (NH2Cl). While free chlorine reacts with natural organic matter in water to produce chlorinated hydrocarbon byproducts, there is also concern that NH2Cl may react with Pb to produce soluble Pb(II) products-leading to elevated Pb levels in drinking water. In this study, electrochemical methods are used to compare the thermodynamics and kinetics of the reduction of these two disinfectants. The standard reduction potential for NH2Cl/Cl- was estimated to be +1.45 V in acidic media and +0.74 V in alkaline media versus NHE using thermodynamic cycles. The kinetics of electroreduction of the two disinfectants was studied using an Au rotating disk electrode. The exchange current densities estimated from Koutecky-Levich plots were 8.2 × 10-5 and 4.1 × 10-5 A/cm2, and by low overpotential experiments were 7.5 ± 0.3 × 10-5 and 3.7 ± 0.4 × 10-5 A/cm2 for free chlorine and NH2Cl, respectively. The rate constant for the electrochemical reduction of free chlorine at equilibrium is approximately twice as large as that for the reduction of NH2Cl. Equilibrium potential measurements show that free chlorine will oxidize Pb to PbO2 above pH 1.7, whereas NH2Cl will oxidize Pb to PbO2 only above about pH 9.5, if the total dissolved inorganic carbon (DIC) is 18 ppm. Hence, NH2Cl is not capable of producing a passivating PbO2 layer on Pb, and could lead to elevated levels of dissolved Pb in drinking water. -------------------------------------------------------------------------------- Reactivity of the Iridium(I) Alkene/Alkyne Complex TpMe2Ir(C2H4)(MeO2CCCCO2Me) Margarita Paneque,* Cristina M. Posadas, Manuel L. Poveda,* Nuria Rendón, and Kurt Mereiter Instituto de Investigaciones Químicas, Departamento de Química Inorgnica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla, Avenida Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain, and Department of Chemistry, Vienna University of Technology, Getreidemarkt 9/164SC, A-1060 Vienna, Austria Received November 16, 2006 Abstract: TpMe2Ir(C2H4)2 (1; TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate) reacts with 1 equiv of MeO2CCCCO2Me (DMAD) at 25 C, via the intermediacy of the known Ir(I) adduct TpMe2Ir(C2H4)(DMAD) (2), with formation of the bis(alkenyl) derivative TpMe2Ir(cis-C(R)=C(R)H)(CH=CH2)(C2H4) (3; R = CO2Me) in ca. 50% yield. Complex 3 slowly evolves to another alkenyl species, TpMe2Ir(cis-C(R)=C(R)H)(CH2CH2CH=CH2) (4), which exists as a mixture of two stereoisomers. Interestingly, complex 2 reacts with the hard Lewis base NCMe at -20 C, giving the Ir(I) adduct TpMe2Ir(DMAD)(NCMe) (5) the first Ir(I) compound of the TpMe2Ir system with a hard ligand. The Ir-NCMe bond in 5 is labile, and the acetonitrile is easily interchanged by CO, C2H4, and the alkynes HCCCO2Me (MP) and DMAD. While with CO the reaction stops at the substitution stage with formation of TpMe2Ir(DMAD)(CO) (8), with C2H4 it gives complex 4 or the bis(alkenyl) species TpMe2Ir(cis-C(R)=C(R)H)(CH=CH2)(NCMe) (9), depending on the concentration of NCMe in the reaction medium. With MP the known iridacyclopentadiene TpMe2Ir(C(R)=C(H)C(R)=C(R))(NCMe) (10) and the symmetrical iridacycloheptatriene TpMe2Ir(C(R)=C(H)C(R)=C(R)C(H)=C(R)(NCMe) (11) can be obtained, while related iridacycles are formed with DMAD. Finally an iridapyrrole with the composition TpMe2Ir(Cl)(C(R)=C(R)C(Me)=NH) (6) is the unexpected result of heating complex 5 in a CH2Cl2-NCMe mixture at 120 C. All of the new compounds reported have been characterized by microanalysis and IR and NMR spectroscopy and, in addition, complexes 4 and 6 have been characterized by single-crystal X-ray studies. -------------------------------------------------------------------------------- A Model-Based Evaluation of Sorptive Reactivities of Hydrous Ferric Oxide and Hematite for U(VI) Je-Hun Jang,* Brian A. Dempsey, and William D. Burgos Environmental Engineering, The Pennsylvania State University, 212 Sackett building, University Park, Pennsylvania 16802 Received for review January 10, 2007 Revised manuscript received April 13, 2007 Accepted April 16, 2007 Abstract: The sorption of uranyl onto hydrous ferric oxide (HFO) or hematite was measured by discontinuously titrating the suspensions with uranyl at pH 5.9, 6.8, and 7.8 under PCO2 = 10-3.5atm (sorption isotherms). Batch reactors were used with equilibration times up to 48 days. Sorption of 1 M uranyl onto HFO was also measured versus pH (sorption edge). A diffuse double layer surface complexation model was calibrated by invoking three sorption species that were consistent with spectroscopic evidence for predominance of bidentate complexes at neutral pH and uranyl-carbonato complexes: >SOH:UO2OH+1, (>SO)2:UO2CO3-2, and (>SO)2  UO2)3(OH)5-1. The model was consistent with previously published isotherm and edge data. The model successfully predicted sorption data onto hematite, only adjusting for different measured specific surface area. Success in application of the model to hematite indicates that the hydrated surface of hematite has similar sorptive reactivity as HFO. -------------------------------------------------------------------------------- |
10楼2007-05-18 21:59:02
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Formation and Degradation Kinetics of the Biofumigant Benzyl Isothiocyanate in Soil Anne Louise Gimsing,* Jes Leisgaard Poulsen, Henrik Laurberg Pedersen, and Hans Christian Bruun Hansen Department of Natural Sciences, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark, and Plant Biochemistry Laboratory, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark Received for review August 18, 2006 Revised manuscript received February 2, 2007 Accepted March 30, 2007 Abstract: Glucosinolates (GSLs) are produced by plants of the Capparales order. Upon enzymatic hydrolysis the GSLs can be transformed to the toxic isothiocyanates (ITCs), which can be used as biofumigants for the control of soil-borne pests. The rates of ITC formation and degradation are critical to both biofumigation and the toxicity and leaching of GSLs and ITCs in soil. Degradation kinetics of benzyl GSL and benzyl ITC in a sandy and clayey surface and subsoil at 8-9 C at natural moisture contents were investigated, as was the rate of formation of ITC from the GSL. Degradation of GSL followed logistic kinetics with t1/2 = 0.7-9.1 days. Degradation was faster in clayey soil compared to sandy soil, and faster in surface soil compared to subsoil. In surface soils, up to 25% of added GSL was detected as ITC, while only 1-6% were detected in the subsoils. ITC degradation followed first-order kinetics with t1/2 = 0.3-1.7 days, with faster degradation in subsoils than in surface soils. Based on the data for GSL hydrolysis and ITC degradation, the concentration of ITC following GSL application was successfully modeled assuming complete conversion of glucosinolate to isothiocyanate and first-order degradation of isothiocyanate. -------------------------------------------------------------------------------- Behavioral and Physiological Changes in Daphnia magna when Exposed to Nanoparticle Suspensions (Titanium Dioxide, Nano-C60, and C60HxC70Hx) Sarah B. Lovern, J. Rudi Strickler, and Rebecca Klaper* University of Wisconsin-Milwaukee, Great Lakes WATER Institute, 600 E. Greenfield Avenue, Milwaukee, Wisconsin 53204 Received for review September 8, 2006 Revised manuscript received March 19, 2007 Accepted April 11, 2007 Abstract: Little is known about the impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia magna at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Exposure to both nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems. -------------------------------------------------------------------------------- Degradation of Well Cement by CO2 under Geologic Sequestration Conditions Barbara G. Kutchko, Brian R. Strazisar,* David A. Dzombak, Gregory V. Lowry, and Niels Thaulow United States Department of Energy, National Energy Technology Laboratory, Pittsburgh, Pennsylvania 15236, Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and RJ Lee Group, Incorporated, Monroeville, Pennsylvania 15146 Received for review November 29, 2006 Revised manuscript received April 11, 2007 Accepted April 12, 2007 Abstract: Experiments were conducted to assess the durability of cements in wells penetrating candidate formations for geologic sequestration of CO2. These experiments showed a significant variation in the initial degradation (9 days of exposure) based on the curing conditions. The high-temperature (50 C) and high-pressure (30.3 MPa) curing environment increased the degree of hydration and caused a change in the microstructure and distribution of the Ca(OH)2(s) phase within the cement. Cement cured at 50 C and 30.3 MPa (representing sequestration conditions) proved to be more resistant to carbonic acid attack than cement cured at 22 C and 0.1 MPa. The cement cured at 50 C and 30.3 MPa exhibited a shallower depth of degradation and displayed a well-defined carbonated zone as compared to cement cured under ambient conditions. This is likely due to smaller, more evenly distributed Ca(OH)2(s) crystals that provide a uniform and effective barrier to CO2 attack. -------------------------------------------------------------------------------- Current-Use Flame Retardants in the Eggs of Herring Gulls (Larus argentatus) from the Laurentian Great Lakes Lewis T. Gauthier, Craig E. Hebert, D. V. Chip Weseloh, and Robert J. Letcher* Science and Technology Branch, National Wildlife Research Centre, Environment Canada, Carleton University, Ottawa, ON, K1A 0H3, Canada, Department of Chemistry, Carleton University, Ottawa, Ontario, K1S 5B6, Canada, Canadian Wildlife Service, Environment Canada, 4905 Dufferin Street, Downsview, Ontario, M3H 5T4, Canada Received for review December 21, 2006 Revised manuscript received April 15, 2007 Accepted April 15, 2007 Abstract: Of the 13, current-use, non-polybrominated diphenyl ether (PBDE) flame retardants (FRs) monitored, hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and - and -isomers of hexabromocyclododecane (HBCD), and the syn- and anti-isomers of the chlorinated Dechlorane Plus (DP) were quantified in egg pools of herring gulls (Larus argentatus) collected in 2004 from six sites in all five of the Laurentian Great Lakes of North America. -HBCD concentrations ranged from 2.1 to 20 ng/g (wet weight (ww)). Other "new" FR levels ranged from 0.004 to 1.4 ng/g ww and were much lower than those of the major BDE congeners that are in technical mixtures (namely BDE-47, -99, -100), where 3PBDE ranged from 186 to 498 ng/g ww. Nineteen hepta-BDEs (hepta = 4.9-11 ng/g ww), octa-BDEs (octa = 2.6-9.1 ng/g ww), and nona-BDEs (nona = 0.12-5.6 ng/g ww) were detectible at all six colonies, while BDE-209 was low but quantifiable (<0.1-0.21 ng/g ww) at two colonies. -DP (syn- and anti-isomers) concentrations in eggs from all sites ranged from 1.5 to 4.5 ng/g ww. Our findings indicate that mother herring gulls are exposed to several, current-use flame retardants via their diet, and in ovo transfer occurred to their eggs. Given the aquatic diet of herring gull, this suggests that there are non-PBDE BFRs present in the gull-associated aquatic food web of the Great Lakes. -------------------------------------------------------------------------------- Biostimulation of PAH Degradation with Plants Containing High Concentrations of Linoleic Acid Haakrho Yi and David E. Crowley* Department of Environmental Sciences, University of California, Riverside, California 92521 Received for review October 6, 2006 Revised manuscript received March 22, 2007 Accepted March 28, 2007 Abstract: Many plant species enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs), but there is little understanding of the mechanisms by which this occurs. This research identified phytochemicals that stimulate pyrene degradation using crushed root tissues from 43 plants that were screened in soil spiked with 100 ppm pyrene. Among the plants tested, root tissues from Apium graveolens (celery), Raphanus sativus (radish), Solanum tuberosum (potato), and Daucus carota (carrot) were most effective for promoting disappearance of pyrene within 40 days. Experiments with A. graveolens showed that plant culture in soil contaminated with pyrene or benzo[a]pyrene was as effective as addition of crushed root tissues. Comparison of the chemical compositions of the effective plants suggested that linoleic acid was the major substance that stimulated PAH degradation. This hypothesis was supported in experiments examining degradation of pyrene and benzo[a]pyrene in soil amended with linoleate, whereas linolenic and palmitic acids did not stimulate degradation within a 20 day period. Antibiotic inhibitor studies implicated gram positive bacteria as a predominant group responding to linoleic acid. These findings provide insight into the mechanisms by which plants enhance degradation of PAHs, and have practical application for remediation of PAH contaminated soils. -------------------------------------------------------------------------------- Evidence for the Migration of Steroidal Estrogens through River Bed Sediments Pierre Labadie, Andrew B. Cundy, Kevin Stone, Michael Andrews, Sam Valbonesi, and Elizabeth M. Hill* Centre for Environmental Research, School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom, and School of the Environment, University of Brighton, Lewes Road, Brighton BN2 4GJ, United Kingdom Received for review December 22, 2006 Revised manuscript received April 4, 2007 Accepted April 16, 2007 Abstract: Estrogenic substances discharged from wastewater treatment plants have been detected in surface sediments of receiving waters, but little is known of their vertical migration through buried sediments and their potential to contaminate subsurface waters. The vertical profiles of estrogenic chemicals were investigated in sediment cores at an alluvial freshwater site (Ditchling) and a clay-rich estuarine site (Lewes), both of which are downstream of wastewater discharges into the River Ouse (Sussex, U.K.). Estrone (E1) was the predominant estrogen detected in surface and buried sediments at both sites and was detected in undisturbed clay sediments >120 years old. Profiles of E1 at Ditchling were characterized by a prominent subsurface peak of E1 at the alluvium/clay interface (-15 cm) at a concentration (28.8 ± 6.0 ng/g of dry wt) that was 9-fold higher than in the surface sediment. In contrast, a steady downcore decline in E1 concentrations was observed in the clay-rich Lewes core. This work provides the first in situ evidence of estrogen migration through river bed sediments and reveals that movement of estrogens through unconsolidated sediment can result in penetration to the underlying substrata and therefore the potential for groundwater contamination. -------------------------------------------------------------------------------- |
11楼2007-05-19 21:51:14
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The Link between Nitrification and Biotransformation of 17-Ethinylestradiol Taewoo Yi and Willie F. Harper, Jr.* Department of Civil Engineering, Environmental Engineering Group, 238 Harbert Engineering Center, Auburn University, Auburn, Alabama 36849 Received for review January 15, 2007 Revised manuscript received April 16, 2007 Accepted April 18, 2007 Abstract: Biological treatment processes are probably important for preventing the proliferation of steroidal compounds in the environment, and a growing number of reports suggest that nitrification may play a role in removing these chemicals from wastewater. The link between nitrification and biotransformation of 17-ethinylestradiol (EE2) was investigated using enriched cultures of autotrophic ammonia-oxidizers. Batch experiments showed that ring A of EE2 is the site of electrophilic initiating reactions, including conjugation and hydroxylation. Ring A was also cleaved before any of the other rings were broken, which is likely because the frontier electron density of the ring A carbon units is higher than those of rings B, C, or D. EE2 and NH3 were degraded in the presence of an ammonium monooxygenase (AMO) containing protein extract, and the reaction stoichiometry was consistent with a conceptual model involving a binuclear copper site located at the AMO active site. Continuous tests showed a linear relationship between nitrification and EE2 removal in enriched nitrifying cultures. Taken together, these results support the notion that EE2 biotransformation can be cometabolically mediated under operating conditions that allow for enrichment of nitrifiers. -------------------------------------------------------------------------------- Temporal Changes in Surface-Water Insecticide Concentrations after the Phaseout of Diazinon and Chlorpyrifos Patrick J. Phillips,* Scott W. Ator, and Elizabeth A. Nystrom U.S. Geological Survey, 425 Jordan Road, Troy, New York, 12180, and U.S. Geological Survey 8987 Yellow Brick Road, Baltimore Maryland 21237 Received for review February 6, 2007 Revised manuscript received April 4, 2007 Accepted April 17, 2007 Abstract: The recent (late 2001) federally mandated phaseout of diazinon and chlorpyrifos insecticide use in outdoor urban settings has resulted in a rapid decline in concentrations of these insecticides in urban streams and rivers in the northeastern and midwestern United States. Assessment of temporal insecticide trends at 20 sites showed that significant step decreases in diazinon concentrations occurred at 90% of the sites after the phaseout, with concentrations generally decreasing by over 50% in summer samples. Chlorpyrifos concentrations showed significant step decreases in at least 1 season at 3 of the 4 sites with sufficient data for analysis. The decrease in diazinon concentrations in response to the phaseout resulted in a decline in the frequency of concentrations exceeding the acute invertebrate water-quality benchmark of 0.1 g/L from 10% of pre-phaseout summer samples to fewer than 1% of post-phaseout summer samples. Although some studies have indicated an increase in concentrations of carbaryl in response to the organophosphorous phaseout, carbaryl concentrations only increased at 1 site after the phaseout. A full assessment of the effect of the phaseout of diazinon and chlorpyrifos on surface water will require data on other insecticides used to replace these compounds. -------------------------------------------------------------------------------- Assessment of Exposure of Workers and Swimmers to Trihalomethanes in an Indoor Swimming Pool J. Caro and M. Gallego* Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, E-14071 Córdoba, Spain Received for review January 12, 2007 Revised manuscript received March 27, 2007 Accepted April 16, 2007 Abstract: A simultaneous study on workers' and swimmers' exposure to trihalomethanes (THMs) in an indoor swimming pool has been carried out by analyzing urine samples using the headspace and gas chromatography-mass spectrometry technique. The subjects of this study were male and female workers of an indoor swimming pool as well as swimmers regularly attending the pool. The results reported show that only chloroform and bromodichloromethane were detected in the urine of those people exposed, which can be used as a specific index of exposure to these compounds. THM uptake of swimmers after 1 h of swimming was higher than that of workers after a 4 h work shift since THM levels in the workers' urine were associated only with inhalation, while levels in swimmers' urine were mainly associated with dermal absorption, apart from inhalation and occasional ingestion, as well as increased uptake due to the physical stress (swimming). The kinetics of THM excretion in the urine of the participants exposed has been calculated after termination of the exposure to select the sampling time and determine the elimination process. An interval of 15 min after exposure was selected as the sampling time, and the absorbed dosage was eliminated by 2 h after exposure. A good correlation between THM concentrations found in the swimming pool water and the urinary THM concentrations of the people affected after exposure has also been obtained. -------------------------------------------------------------------------------- |
12楼2007-05-19 21:52:56
13楼2007-05-19 21:53:17
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Membrane Independent Limiting Flux for RO and NF Membranes Fouled by Humic Acid Chuyang Y. Tang* and James O. Leckie Environmental Engineering and Science, Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020 Received for review December 31, 2006 Revised manuscript received April 11, 2007 Accepted April 16, 2007 Abstract: The flux decline of reverse osmosis and nanofiltration membranes was investigated under constant pressure conditions during humic acid fouling tests. For a given membrane type under a given feedwater composition, increasing pressure resulted in increased flux reduction and foulant accumulation. A limiting flux seems to exist beyond which the membrane flux cannot be sustained. Membranes with initial fluxes greater than the limiting flux experienced severe fouling and their pseudo stable fluxes approached the limiting flux. Flux reduction was much milder when the initial flux was lower than the limiting flux. Furthermore, the limiting flux seems to be independent of membrane properties, probably due to the dominance of foulant-deposited-foulant interaction upon complete foulant coverage over membrane surfaces. On the other hand, strong dependence of the limiting flux on the feedwater composition was observed. The limiting flux was reduced at higher proton, calcium, and/or background electrolytes concentra tions, likely due to reduced electrostatic repulsion under these conditions. -------------------------------------------------------------------------------- The Chronic Toxicity of Alcohol Alkoxylate Surfactants on Anaerobic Granular Sludge in the Pulp and Paper Industry Steven W. Van Ginkel,* Sjon J. M. Kortekaas,# and Jules B. van Lier Lettinga Associates Foundation, P.O. Box 500, 6700 AM, Wageningen, The Netherlands, Subdepartment of Environmental Technology, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands, and Department of Civil and Environmental Engineering, Pennsylvania State University, University Park, Pennsylvania, 16801 Received for review December 21, 2006 Revised manuscript received March 24, 2007 Accepted April 4, 2007 Abstract: The chronic toxicity of an alcohol alkoxylate surfactant used in the pulp and paper industry was observed in methanogenic consortia under unfed conditions. Methanogenic inhibition was not observed until 250 h of famine conditions while in the presence of the surfactant. The delayed onset of inhibition is likely due to the amount of time necessary for the surfactant to partition into the cellular membrane which uncouples cellular energy conservation mechanisms and exhausts internal energy reserves necessary to maintain homeostasis. -------------------------------------------------------------------------------- Electron Pulse Radiolysis Determination of Hydroxyl Radical Rate Constants with Suwannee River Fulvic Acid and Other Dissolved Organic Matter Isolates Paul Westerhoff,* Stephen P. Mezyk, William J. Cooper, and Daisuke Minakata Department of Civil and Environmental Engineering, Arizona State University, Box 5306, Tempe, Arizona 85287-5306, Department of Chemistry and Biochemistry, California State University at Long Beach, Long Beach, California 90840, and Urban Water Research Center and Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, California 92697-2175 Received for review October 20, 2006 Revised manuscript received April 1, 2007 Accepted April 13, 2007 Abstract: Pulse radiolysis experiments were conducted on dissolved organic matter (DOM) samples isolated as hydrophobic and hydrophilic acids and neutrals from different sources (i.e., stream, lake, wastewater treatment plant). Absolute bimolecular reaction rate constants for the reaction of hydroxyl radicals (OH) with DOM (kOH, DOM) were determined. kOH, DOM values are expressed as moles of carbon. Based on direct measurement of transient DOM radicals (DOM) and competition kinetic techniques, both using pulse radiolysis, the kOH, DOM value for a standard fulvic acid from the Suwannee River purchased from the International Humic Substances Society was (1.60 ± 0.24) × 108 M-1 s-1. Both pulse radiolysis methods yielded comparable kOH, DOM values. The kOH, DOM values for the seven DOM isolates from different sources ranged from 1.39 × 108 M-1 s-1 to 4.53 × 108 M-1 s-1, and averaged 2.23 × 108 M-1 s-1 (equivalent to 1.9 × 104 (mgC/L)-1 s-1). These values represent the first direct measurements of kOH, DOM, and they compare well with literature values obtained via competition kinetic techniques during ozone or ultraviolet irradiation experiments. More polar, lower-molecular-weight DOM isolates from wastewater have higher kOH, DOM values. In addition, the formation (microsecond time scale) and decay (millisecond time scale) of DOM transients were observed for the first time. DOM from hydrophobic acids exhibited broader absorbance spectra than transphilic acids, while wastewater DOM isolates had narrower DOM spectra more skewed toward shorter wavelengths than did DOM spectra for hydrophobic acids. -------------------------------------------------------------------------------- |
14楼2007-05-23 13:38:03
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