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2007-4-20 最新EST文章和摘要
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Area of Influence (AOI) Development: Fast Generation of Receptor-Oriented Sensitivity Fields for Use in Regional Air Quality Modeling Florian D. Habermacher, Sergey L. Napelenok,* Farhan Akhtar, Yongtao Hu, and Armistead G. Russell School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, Environmental Sciences and Engineering Section, Swiss Federal Institute of Technology in Lausanne, 1015 Lausanne, Switzerland, and Department of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332 Received for review September 8, 2006 Revised manuscript received March 7, 2007 Accepted March 14, 2007 Abstract: An approach is developed and tested to extend discrete, source-based sensitivity results to provide a complete set of information for source-air quality impacts, including inversion of those results to develop receptor-oriented source-impact sensitivities. First, the decoupled direct sensitivity analysis method in 3D (DDM-3D) is used to calculate a finite number of forward sensitivities from discrete points. These results are then interpolated using tessellation to provide complete fields of forward, emissions-based sensitivities, i.e., how emissions in any one grid cell within the domain impact any other cell. Receptor-oriented sensitivities are then found by inverting the set of forward sensitivities and can be used to identify the area of influence (AOI). This economically provides results similar to what would be found using an adjoint model. The present approach is computationally less intensive than adjoint modeling for a large number of receptors, and provides both source-oriented and receptor-oriented pollutant response fields that can be used for air quality management and health impact analyses. The forward sensitivity interpolation procedure, as well as the receptor-oriented sensitivities, is evaluated using data withholding. -------------------------------------------------------------------------------- Source Apportionment of Atmospheric PAHs in the Western Balkans by Natural Abundance Radiocarbon Analysis Zdenek Zencak, Jana Klanova, Ivan Holoubek, and Örjan Gustafsson* Department of Applied Environmental Science (ITM), Stockholm University, 10691 Stockholm, Sweden, and Research Centre for Environmental Chemistry and Ecotoxicology (RECETOX), Masaryk University, Kamenice 126/3, 625 00 Brno, Czech Republic Received for review December 6, 2006 Revised manuscript received March 25, 2007 Accepted March 27, 2007 Abstract: Progress in source apportionment of priority combus tion-derived atmospheric pollutants can be made by an inverse approach to inventory emissions, namely, receptor-based compound class-specific radiocarbon analysis (CCSRA) of target pollutants. In the present study, CCSRA of the combustion-derived polycyclic aromatic hydrocarbons (PAHs) present in the atmosphere of the countries of the former republic of Yugoslavia was performed. The carbon stable isotope composition (13C) of PAHs varied between -27.68 and -27.19”, whereas 14C values ranged from -568” for PAHs sampled in Kosovo to -288” for PAHs sampled in the Sarajevo area. The application of an isotopic mass balance model to these 14C data revealed a significant contribution (35-65%) from the combustion of non-fossil material to the atmospheric PAH pollution, even in urban and industrialized areas. Furthermore, consistency was observed between the isotopic composition of PAHs obtained by high-volume sampling and those collected by passive sampling. This encourages the use of passive samplers for CCSRA applications. This marks the first time that a CCSRA investigation could be executed on a geographically wide scale, providing a quantitative field-based source apportionment, which points out that also non-fossil combustion processes should be targeted for remedial action. -------------------------------------------------------------------------------- Determinants of Fetal Exposure to Polyfluoroalkyl Compounds in Baltimore, Maryland Benjamin J. Apelberg, Lynn R. Goldman,* Antonia M. Calafat, Julie B. Herbstman, Zsuzsanna Kuklenyik, Jochen Heidler, Larry L. Needham, Rolf U. Halden, and Frank R. Witter Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, and Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 Received for review January 12, 2007 Revised manuscript received March 20, 2007 Accepted March 21, 2007 Abstract: Polyfluoroalkyl compounds (PFCs), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), are ubiquitous, man-made chemicals. Human data suggest that in utero exposures to these chemicals occur and some evidence of developmental toxicity in animals exists. To assess the distribution and determinants of fetal exposure to PFCs, we analyzed cord serum samples from 299 singleton newborns delivered between 2004 and 2005 in Baltimore, MD for 10 PFCs by employing on-line solid-phase extraction coupled with reversed-phase high-performance liquid chromatography-tandem mass spectrometry. PFOS and PFOA were detected in 99 and 100% of umbilical cord sera, with geometric mean concentrations of 4.9 and 1.6 ng/mL, respectively. PFOS and PFOA concentrations were highly correlated (Pearson's r = 0.64 after natural log transformation, p < 0.01). Eight other PFCs were detected less frequently and at lower concentrations than PFOS and PFOA. Geometric mean concentrations of PFOS for Asians (6.0 ng/mL) and Blacks (5.1 ng/mL) were higher than those for Whites (4.2 ng/mL), while PFOA levels were more evenly distributed by race. Other maternal demographic and socioeconomic characteristics, including age, education, marital status, and living in the city limits were not significantly associated with cord concentrations. Our findings suggest that in utero exposure to PFOS and PFOA is ubiquitous in a population of babies born in Baltimore, MD. -------------------------------------------------------------------------------- Microbial Fuel Cell Operation with Continuous Biological Ferrous Iron Oxidation of the Catholyte Annemiek ter Heijne, Hubertus V. M. Hamelers,* and Cees J. N. Buisman Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen, The Netherlands, and Wetsus, Centre for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands Received for review February 5, 2007 Revised manuscript received March 13, 2007 Accepted March 14, 2007 Abstract: The oxygen reduction rate at the cathode is a limiting factor in microbial fuel cell (MFC) performance. In our previous study, we showed the performance of an MFC with ferric iron (Fe3+) reduction at the cathode. Instead of oxygen, ferric iron was reduced to ferrous iron (Fe2+) at the cathode with a bipolar membrane between the anode and cathode compartment. This resulted in a higher cathode potential than is usually obtained with oxygen on metal-based chemical catalysts in MFCs. In this study, we investigated the operation of the same MFC with ferric iron reduction at the cathode and simultaneous biological ferrous iron oxidation of the catholyte. We show that the immobilized microorganism Acidithiobacillus ferrooxidans is capable of oxidizing ferrous iron to ferric iron at a rate high enough to ensure an MFC power output of 1.2 W/m2 and a current of 4.4 A/m2. This power output was 38% higher than in our previous study at a similar current density without ferrous iron oxidation. The bipolar membrane is shown to split water into 65-76% of the needed protons and hydroxides. The other part of the protons was supplied as H2SO4 to the cathode compartment. The remaining charge was transported by K+ and HSO4-/SO42- from the one compartment to the other. This resulted in increased salt concentrations in the cathode. The increased salt concentrations reduced the ohmic losses and enabled the improved MFC power output. Iron could be reversibly removed from the bipolar membrane by exchange with protons. -------------------------------------------------------------------------------- |
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