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611.
Metal binding properties of extracellular polymeric substances extracted from anaerobic granular sludges 总被引:1,自引:0,他引:1
Paul d’Abzac François Bordas Emmanuel Joussein Eric D. van Hullebusch Piet N. L Lens Gilles Guibaud 《Environmental science and pollution research international》2013,20(7):4509-4519
Extracellular polymeric substances (EPS) were extracted from four anaerobic granular sludges with different procedures to study their involvement in biosorption of metallic elements. EPS extracts are composed of closely associated organic and mineral fractions. The EPS macromolecules (proteins, polysaccharides, humic-like substances, nucleic, and uronic acids) have functional groups potentially available for the binding of metallic elements. The acidic constants of these ionizable groups are: pK a1 (4–5) corresponding to the carboxyl groups; pK a2 (6–7) corresponding to the phosphoric groups; pK a3 (8–10) and pK a4 (≈10) corresponding to the phenolic, hydroxyl, and amino groups. The polarographic study confirms the higher affinity of the EPS to bind to lead than to cadmium. Moreover, the binding of these metallic compounds with the EPS is a mix of several sorption mechanisms including surface complexation, ion exchange, and flocculation. Inorganic elements were found as ions linked to organic molecules or as solid particles. The mineral fraction affects the binding properties of the EPS, as the presence of salts decreases the EPS binding ability. Calcite and apatite particles observed on SEM images of EPS extracts can also sorb metallic elements through ion exchange or surface complexation. 相似文献
612.
Jacob F. Thomas Richard M. Engeman Eric A. Tillman Justin W. Fischer Steve L. Orzell Deborah H. Glueck Rodney K. Felix Michael L. Avery 《Environmental science and pollution research international》2013,20(3):1503-1510
Ecological sampling can be labor intensive, and logistically impractical in certain environments. We optimize line intercept sampling and compare estimation methods for assessing feral swine damage within fragile wetland ecosystems in Florida. Sensitive wetland sites, and the swine damage within them, were mapped using GPS technology. Evenly spaced parallel transect lines were simulated across a digital map of each site. The length of each transect and total swine damage under each transect were measured and percent swine damage within each site was estimated by two methods. The total length method (TLM) combined all transects as a single long transect, dividing the sum of all damage lengths across all transects by the combined length of all transect lines. The equal weight method (EWM) calculated the damage proportion for each transect line and averaged these proportions across all transects. Estimation was evaluated using transect spacings of 1, 3, 5, 10, 15, and 20 m. Based on relative root mean squared error and relative bias measures, the TLM produced higher quality estimates than EWM at all transect spacings. Estimation quality decreased as transect spacing increased, especially for TLM. Estimation quality also increased as the true proportion of swine damage increased. Diminishing improvements in estimation quality as transect spacings decreased suggested 5 m as an optimal tradeoff between estimation quality and labor. An inter-transect spacing of 5 m with TLM estimation appeared an optimal starting point when designing a plan for estimating swine damage, with practical, logistical, economic considerations determining final design details. 相似文献
613.
Robert E. Kohn Eric Weger 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1045-1047
In recent years, there has been a downward trend in sulfur dioxide concentrations in downtown St. Louis. This paper examines the contribution to this trend from locational changes of polluting sources and from technological abatement. A simple diffusion model is used to relate annual average concentrations to annual emission data. The results suggest that, had there been no abatement activity, the changes in location of sources that occurred between 1963 and 1970 have more or less offset a 40% increase in annual emissions over that period. However, the abatement activity, essentially the consequence of air pollution regulations, may possibly be credited with a decline of 35% in the annual average concentration. 相似文献
614.
Daniel Grosjean Edwin L. Williams II 《Journal of the Air & Waste Management Association (1995)》2013,63(6):805-809
A one-year survey of air quality has been carried out at two southern California inland locations, Perris and Palm Springs (90 km E-SE and 120 km E of Los Angeles) to evaluate transport of photochemical smog from the Los Angeles area and to assess population exposure to toxic air pollutants in the Coachella Valley and eastern Riverside County. Air pollutants measured included formaldehyde, acetaldehyde, nitric acid, and peroxyacetyl nitrate (PAN). Acetic acid was also measured as part of the time-integrated method employed to measure PAN. In addition, intensive studies were carried out at both locations and included measurements of aldehydes, nitric acid, PAN, peroxypropionyl nitrate (PPN), methylchloroform and tetrachloroethylene. Maximum concentrations of HCHO, CH3CHO, HNO3, PAN, PPN, CH3COOH and C2CI4 were 26, 21, 4.5, 7.6, 0.42, 6.6 and 0.29 ppb in Palm Springs and 15, 30, 6.3, 9.1, 0.73, 7.8 and 0.43 ppb in Perris. Pollutant concentrations measured in Palm Springs and Perris are compared to those measured in the Los Angeles area, and are discussed in terms of formation and removal during transport. 相似文献
615.
Steven H. Cadle Patricia Mulawa Eric C. Hunsanger Ken Nelson Ronald A. Ragazzi Richard Barrett 《Journal of the Air & Waste Management Association (1995)》2013,63(9):164-174
ABSTRACT A study of particulate matter (PM) emissions from in-use, light-duty vehicles was conducted during the summer of 1996 and the winter of 1997 in the Denver, CO, region. Vehicles were tested as received on chassis dynamometers on the Federal Test Procedure Urban Dynamometer Driving Schedule (UDDS) and the IM240 driving schedule. Both PM10 and regulated emissions were measured for each phase of the UDDS. For the summer portion of the study, 92 gasoline vehicles, 10 diesel vehicles, and 9 gasoline vehicles with visible smoke emissions were tested once. For the winter, 56 gasoline vehicles, 12 diesel vehicles, and 15 gasoline vehicles with visible smoke were tested twice, once indoors at 60 °F and once outdoors at the prevailing temperature. Vehicle model year ranged from 1966 to 1996. Impactor particle size distributions were obtained on a subset of vehicles. Continuous estimates of the particle number emissions were obtained with an electrical aerosol analyzer. This data set is being provided to the Northern Front Range Air Quality Study program and to the State of Colorado and the U.S. Environmental Protection Agency for use in updating emissions inventories. 相似文献
616.
D. Alan Hansen Eric Edgerton Ben Hartsell John Jansen Harriet Burge Petros Koutrakis 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1445-1458
Abstract Measurements of pollutant gases, airborne particulate matter mass and composition, and meteorology have been made at a core site near downtown Atlanta, GA, since August 1998 in support of the Aerosol Research and Inhalation Epidemiology Study (ARIES). This site is one of eight in the Southeastern Aerosol Research and Characterization network. The measurement objective is to provide a long-term, multivariate dataset suitable for investigating statistical associations of respiratory and cardiovascular disease with airborne particulate matter composition, meteorology, and copollutant gases through epidemiologic modeling. Measurements are expected to continue through 2010. Ancillary multiyear measurements at additional sites in the Atlanta metropolitan area and in short-term exposure assessments have been used to estimate the exposure/measurement error associated with using data from a central site to approximate human exposures for the entire area. To date, 13-, 25-, and 53-month air quality datasets have been used in epidemiologic analyses. 相似文献
617.
Diana Ceballos Eric Fujita John Sagebiel 《Journal of the Air & Waste Management Association (1995)》2013,63(3):355-365
Abstract Gasoline tracers were collected on solid-phase microextraction (SPME) fibers and analyzed by capillary gas chromatography with photoionization detector (GC/PID). This was part of a larger study to quantify personal exposure to motor vehicle gasoline evaporative and combustive emissions in high-end exposure microenvironments (MEs). The SPME fiber selected for this application was a 75-µm carboxen/polydimethylsiloxane. Sequential 10-min samples were collected for measurement of benzene, toluene, ethylbenzene, and ortho-, meta-, and para-xylene in different MEs in Atlanta, GA, in summer 2002 and Reno, NV, in spring 2003. Field calibrations were performed with certified gas standards in 1-L Tedlar bags for varying concentrations and exposure times. SPME detection limits were ~0.2 ppbv with a precision of 3–17% and accuracy of 30%. A dynamic system was designed for temperature and relative humidity calibrations, with corrections for the effects of these variables performed when necessary. SPME data compared satisfactorily with integrated canister samples, continuous PID, and field portable mass spectrometer data. 相似文献
618.
Eric S. Edgerton Benjamin E. Hartsell Rick D. Saylor John J. Jansen D. Alan Hansen George M. Hidy 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1325-1341
Abstract Deployment of continuous analyzers in the Southeastern Aerosol Research and Characterization Study (SEARCH) network began in 1998 and continues today as new technologies are developed. Measurement of fine particulate matter (PM2.5) mass is performed using a dried, 30 °C tapered element oscillating microbalance (TEOM). TEOM measurements are complemented by observations of light scattering by nephelometry. Measurements of major constituents include: (1) SO4 2? via reduction to SO2; (2) NH4 + and NO3 ? via respective catalytic oxidation and reduction to NO, (3) black carbon (BC) by optical absorption, (4) total carbon by combustion to CO2, and (5) organic carbon by difference between the latter two measurements. Several illustrative examples of continuous data from the SEARCH network are presented. A distinctive composite annual average diurnal pattern is observed for PM2.5 mass, nitrate, and BC, likely indicating the influence of traffic-related emissions, growth, and break up of the boundary layer and formation of ammonium nitrate. Examination of PM2.5 components indicates the need to better understand the continuous composition of the unmeasured “other” category, because it contributes a significant fraction to total mass during periods of high PM2.5 loading. Selected episodes are presented to illustrate applications of SEARCH data. An SO2 conversion rate of 0.2%/hr is derived from an observation of a plume from a coal-fired power plant during early spring, and the importance of local, rural sources of NH3 to the formation of ammonium nitrate in particulate matter (PM) is demonstrated. 相似文献
619.
Michael Van Loy Tina Bahadori Ron Wyzga Ben Hartsell Eric Edgerton 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1446-1458
ABSTRACT The Aerosol Research and Inhalation Epidemiology Study (ARIES) was designed to provide high-quality measurements of PM25, its components, and co-varying pollutants for an air pollution epidemiology study in Atlanta, GA. Air pollution epidemiology studies have typically relied on available data on particle mass often collected using filter-based methods. Filter-based PM2.5 sampling is susceptible to both positive and negative errors in the measurement of aerosol mass and particle-phase component concentrations in the undisturbed atmosphere. These biases are introduced by collection of gas-phase aerosol components on the filter media or by volatilization of particle phase components from collected particles. As part of the ARIES, we collected daily 24-hr PM2.5 mass and speciation samples and continuous PM2.5 data at a mixed residential-light industrial site in Atlanta. These data facilitate analysis of the effects of a wide variety of factors on sampler performance. We assess the relative importance of PM2.5 components and consider associations and potential mechanistic linkages of PM2.5 mass concentrations with several PM2.5 components. For the 12 months of validated data collected to date (August 1, 1998-July 31, 1999), the monthly average Federal Reference Method (FRM) PM2 5 mass always exceeded the proposed annual average standard (12-month average = 20.3 ± 9.5 ug/m3). The particulate SO4 2- fraction (as (NH4)2SO4) was largest in the summer and exceeded 50% of the FRM mass. The contribution of (NH4)2SO4 to FRM PM2.5 mass dropped to less than 30% in winter. Particu-late NO3 - collected on a denuded nylon filter averaged 1.1 ± 0.9 ug/m3. Particle-phase organic compounds (as organic carbon × 1.4) measured on a denuded quartz filter sampler averaged 6.4 ± 3.1 ug/m3 (32% of FRM PM2 5 mass) with less seasonal variability than SO4 2-. 相似文献
620.
Eric S. Edgerton Benjamin E. Hartsell Rick D. Saylor John J. Jansen D. Alan Hansen George M. Hidy 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1527-1542
Abstract The Southeastern Aerosol Research and Characterization Study (SEARCH) was implemented in 1998–1999 to provide data and analyses for the investigation of the sources, chemical speciation, and long-term trends of fine particulate matter (PM2.5) and coarse particulate matter (PM10–2.5) in the Southeastern United States. This work is an initial analysis of 5 years (1999–2003) of filter-based PM2.5 and PM10–2.5 data from SEARCH. We find that annual PM2.5 design values were consistently above the National Ambient Air Quality Standards (NAAQS) 15 µg/m3 annual standard only at monitoring sites in the two largest urban areas (Atlanta, GA, and North Birmingham, AL). Other sites in the network had annual design values below the standard, and no site had daily design values above the NAAQS 65 µg/m3 daily standard. Using a particle composition monitor designed specifically for SEARCH, we found that volatilization losses of nitrate, ammonium, and organic carbon must be accounted for to accurately characterize atmospheric particulate matter. In particular, the federal reference method for PM2.5 underestimates mass by 3–7% as a result of these volatilization losses. Organic matter (OM) and sulfate account for ≥60% of PM2.5 mass at SEARCH sites, whereas major metal oxides (MMO) and unidentified components (“other”) account for ≥80% of PM10–2.5 mass. Limited data suggest that much of the unidentified mass in PM10–2.5 may be OM. For paired comparisons of urban-rural sites, differences in PM2.5 mass are explained, in large part, by higher OM and black carbon at the urban site. For PM10, higher urban concentrations are explained by higher MMO and “other.” Annual means for PM2.5 and PM10–2.5 mass and major components demonstrate substantial declines at all of the SEARCH sites over the 1999–2003 period (10–20% in the case of PM2.5, dominated by 14–20% declines in sulfate and 11–26% declines in OM, and 14–25% in the case of PM10–2.5, dominated by 17–30% declines in MMO and 14–31% declines in “ other”). Although declining national emissions of sulfur dioxide and anthropogenic carbon may account for a portion of the observed declines, additional investigation will be necessary to establish a quantitative assessment, especially regarding trends in local and regional emissions, primary carbon emissions, and meteorology. 相似文献