The Experts below are selected from a list of 3321 Experts worldwide ranked by ideXlab platform
John G. Watson - One of the best experts on this subject based on the ideXlab platform.
-
Chemical Mass Balance source apportionment for combined pm2 5 measurements from u s non urban and urban long term networks
Atmospheric Environment, 2010Co-Authors: L Antony W Chen, Judith C. Chow, John G. Watson, David Dubois, Lisa HerschbergerAbstract:Abstract The Minnesota Particulate Matter 2.5 (PM2.5) Source Apportionment Study was undertaken to explore the utility of PM2.5 Mass, element, ion, and carbon measurements from long-term speciation networks for pollution source attribution. Ambient monitoring data at eight sites across the state were retrieved from the archives of the Interagency Monitoring of Protected Visual Environments (IMPROVE) and the Speciation Trends Network (STN; part of the Chemical Speciation Network [CSN]) and analyzed by an Effective Variance – Chemical Mass Balance (EV-CMB) receptor model with region-specific geological source profiles developed in this study. PM2.5 was apportioned into contributions of fugitive soil dust, calcium-rich dust, taconite (low grade iron ore) dust, road salt, motor vehicle exhaust, bioMass burning, coal-fired utility, and secondary aerosol. Secondary sulfate and nitrate contributed strongly (49–71% of PM2.5) across all sites and was dominant (≥60%) at IMPROVE sites. Vehicle exhausts accounted for 20–70% of the primary PM2.5 contribution, largely exceeding the proportion in the primary PM2.5 emission inventory. The diesel exhaust contribution was separable from the gasoline engine exhaust contribution at the STN sites. Higher detection limits for several marker elements in the STN resulted in non-detectable coal-fired boiler contributions which were detected in the IMPROVE data. Despite the different measured variables, analytical methods, and detection limits, EV-CMB results from a nearby IMPROVE-STN non-urban/urban sites showed similar contributions from regional sources – including fugitive dust and secondary aerosol. Seasonal variations of source contributions were examined and extreme PM2.5 episodes were explained by both local and regional pollution events.
-
simulating changes in source profiles from coal fired power stations use in Chemical Mass Balance of pm2 5 in the mount zirkel wilderness
Energy & Fuels, 2002Co-Authors: John G. Watson, Judith C. Chow, Norman F. Robinson, Douglas H. Lowenthal, Catherine F Cahill, Donald L BlumenthalAbstract:An aerosol evolution model that incorporates explicit Chemical changes for gas and aqueous phase sulfur reactions and equilibrium with gaseous precursors is used to simulate the change in coal-fired power station source emissions for a variety of conditions. These “aged” profiles are used in a Chemical Mass Balance (CMB) source apportionment to estimate the amount of PM2.5 and sulfate contributed by local power stations vs regional sources at locations near the Mt. Zirkel Wilderness Area in northwestern Colorado. On average, local power station contributions were negligible because gas-phase conversion created insufficient sulfate during reasonable plume aging periods. However, when plumes were combined with fogs in the nearby Yampa Valley prior to transport to the Wilderness, substantial fractions of sulfate, with corresponding contributions to light extinction, were estimated by the CMB. These contributions were qualitatively consistent with independent hourly measurements of particle light scattering, ...
-
review of pm2 5 and pm10 apportionment for fossil fuel combustion and other sources by the Chemical Mass Balance receptor model
Energy & Fuels, 2002Co-Authors: Judith C. Chow, John G. WatsonAbstract:This review examines how the Chemical Mass Balance (CMB) receptor model has been used to quantify source contributions from fossil fuel combustion and other sources to ambient concentrations of PM2.5 and PM10 for urban and regional scales. Nonfossil fuel sources, such as fugitive dust, cooking, vegetative burning, and natural or human-caused biogenics must be considered together with fossil-fuel sources in a CMB analysis to obtain closure for PM2.5 and PM10 Mass. CMB analyses in 22 different studies have found fossil fuel combustion to be a large contributor to PM2.5 and PM10 concentrations, with most of the primary contributions originating form diesel- and gasoline-powered vehicle exhaust. Primary contributions from ducted sources, such as coal- and oil-fired power stations, are negligible when these facilities have been modernized with effective pollution controls, but they have been shown to be large contributors without these controls. Secondary sulfates and nitrates from fossil fuel combustion are r...
-
review of volatile organic compound source apportionment by Chemical Mass Balance
Atmospheric Environment, 2001Co-Authors: John G. Watson, Judith C. Chow, Eric M FujitaAbstract:The Chemical Mass Balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the Chemical compounds used in the calculation, the apportionment units, and the source profiles applied. Nevertheless, they show similar results for VOC fractions contributed by different sources. Gasoline vehicle exhaust, liquid gasoline, and gasoline evaporation contribute up to 50% or more of the ambient VOCs in many of these studies. Relative motor vehicle source contributions determined by CMB were similar to or larger than their proportions in emissions inventories. Coatings and solvent contributions from CMB were much lower than the proportions attributed to these sources in current emissions inventories. Several measurement and reporting conventions would facilitate CMB analyses of VOC data sets.
-
second generation Chemical Mass Balance source apportionment of sulfur oxides and sulfate at the grand canyon during the project mohave summer intensive
Journal of The Air & Waste Management Association, 2000Co-Authors: Delbert J Eatough, Robert J Farber, John G. WatsonAbstract:ABSTRACT Receptor-based Chemical Mass Balance (CMB) analysis techniques are designed to apportion species that are conserved during pollutant transport using conserved source profiles. The techniques will fail if non-conservative species (or profiles) are not properly accounted for in the CMB model. The straightforward application of the CMB model developed for Project MOHAVE using regional profiles resulted in a significant under-prediction of total sulfate oxides (SOx, SO2 plus fine particulate sulfate) for many samples at Meadview, AZ. In addition, for these samples the concentration of the inert tracer emitted from the MOHAVE Power Project (MPP), ocPDCH, was also under-predicted. A second-generation model has been developed which assumes that separation of particles and SO2 can occur in the MPP plume during nighttime stable plume conditions. This second-generation CMB model accounts for all SOx present at the various receptor sites. In addition, the concentrations of ocPDCH and the presence of other i...
Judith C. Chow - One of the best experts on this subject based on the ideXlab platform.
-
Chemical Mass Balance source apportionment for combined pm2 5 measurements from u s non urban and urban long term networks
Atmospheric Environment, 2010Co-Authors: L Antony W Chen, Judith C. Chow, John G. Watson, David Dubois, Lisa HerschbergerAbstract:Abstract The Minnesota Particulate Matter 2.5 (PM2.5) Source Apportionment Study was undertaken to explore the utility of PM2.5 Mass, element, ion, and carbon measurements from long-term speciation networks for pollution source attribution. Ambient monitoring data at eight sites across the state were retrieved from the archives of the Interagency Monitoring of Protected Visual Environments (IMPROVE) and the Speciation Trends Network (STN; part of the Chemical Speciation Network [CSN]) and analyzed by an Effective Variance – Chemical Mass Balance (EV-CMB) receptor model with region-specific geological source profiles developed in this study. PM2.5 was apportioned into contributions of fugitive soil dust, calcium-rich dust, taconite (low grade iron ore) dust, road salt, motor vehicle exhaust, bioMass burning, coal-fired utility, and secondary aerosol. Secondary sulfate and nitrate contributed strongly (49–71% of PM2.5) across all sites and was dominant (≥60%) at IMPROVE sites. Vehicle exhausts accounted for 20–70% of the primary PM2.5 contribution, largely exceeding the proportion in the primary PM2.5 emission inventory. The diesel exhaust contribution was separable from the gasoline engine exhaust contribution at the STN sites. Higher detection limits for several marker elements in the STN resulted in non-detectable coal-fired boiler contributions which were detected in the IMPROVE data. Despite the different measured variables, analytical methods, and detection limits, EV-CMB results from a nearby IMPROVE-STN non-urban/urban sites showed similar contributions from regional sources – including fugitive dust and secondary aerosol. Seasonal variations of source contributions were examined and extreme PM2.5 episodes were explained by both local and regional pollution events.
-
evaluations of the Chemical Mass Balance method for determining contributions of gasoline and diesel exhaust to ambient carbonaceous aerosols
Journal of The Air & Waste Management Association, 2007Co-Authors: Eric M Fujita, Judith C. Chow, David E Campbell, W P Arnott, Barbara ZielinskaAbstract:Abstract The US. Department of Energy Gasoline/Diesel PM Split Study was conducted to assess the sources of uncertainties in using an organic compound–based Chemical Mass Balance receptor model to quantify the relative contributions of emissions from gasoline (or spark ignition [SI]) and diesel (or compression ignition [CI]) engines to ambient concentrations of fine particulate matter (PM2.5) in California’s South Coast Air Basin (SOCAB). In this study, several groups worked cooperatively on source and ambient sample collection and quality assurance aspects of the study but worked independently to perform Chemical analysis and source apportionment. Ambient sampling included daily 24–hr PM2.5 samples at two air quality–monitoring stations, several regional urban locations, and along freeway routes and surface streets with varying proportions of automobile and truck traffic. Diesel exhaust was the dominant source of total carbon (TC) and elemental carbon (EC) at the Azusa and downtown Los Angeles, CA, monit...
-
simulating changes in source profiles from coal fired power stations use in Chemical Mass Balance of pm2 5 in the mount zirkel wilderness
Energy & Fuels, 2002Co-Authors: John G. Watson, Judith C. Chow, Norman F. Robinson, Douglas H. Lowenthal, Catherine F Cahill, Donald L BlumenthalAbstract:An aerosol evolution model that incorporates explicit Chemical changes for gas and aqueous phase sulfur reactions and equilibrium with gaseous precursors is used to simulate the change in coal-fired power station source emissions for a variety of conditions. These “aged” profiles are used in a Chemical Mass Balance (CMB) source apportionment to estimate the amount of PM2.5 and sulfate contributed by local power stations vs regional sources at locations near the Mt. Zirkel Wilderness Area in northwestern Colorado. On average, local power station contributions were negligible because gas-phase conversion created insufficient sulfate during reasonable plume aging periods. However, when plumes were combined with fogs in the nearby Yampa Valley prior to transport to the Wilderness, substantial fractions of sulfate, with corresponding contributions to light extinction, were estimated by the CMB. These contributions were qualitatively consistent with independent hourly measurements of particle light scattering, ...
-
review of pm2 5 and pm10 apportionment for fossil fuel combustion and other sources by the Chemical Mass Balance receptor model
Energy & Fuels, 2002Co-Authors: Judith C. Chow, John G. WatsonAbstract:This review examines how the Chemical Mass Balance (CMB) receptor model has been used to quantify source contributions from fossil fuel combustion and other sources to ambient concentrations of PM2.5 and PM10 for urban and regional scales. Nonfossil fuel sources, such as fugitive dust, cooking, vegetative burning, and natural or human-caused biogenics must be considered together with fossil-fuel sources in a CMB analysis to obtain closure for PM2.5 and PM10 Mass. CMB analyses in 22 different studies have found fossil fuel combustion to be a large contributor to PM2.5 and PM10 concentrations, with most of the primary contributions originating form diesel- and gasoline-powered vehicle exhaust. Primary contributions from ducted sources, such as coal- and oil-fired power stations, are negligible when these facilities have been modernized with effective pollution controls, but they have been shown to be large contributors without these controls. Secondary sulfates and nitrates from fossil fuel combustion are r...
-
review of volatile organic compound source apportionment by Chemical Mass Balance
Atmospheric Environment, 2001Co-Authors: John G. Watson, Judith C. Chow, Eric M FujitaAbstract:The Chemical Mass Balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the Chemical compounds used in the calculation, the apportionment units, and the source profiles applied. Nevertheless, they show similar results for VOC fractions contributed by different sources. Gasoline vehicle exhaust, liquid gasoline, and gasoline evaporation contribute up to 50% or more of the ambient VOCs in many of these studies. Relative motor vehicle source contributions determined by CMB were similar to or larger than their proportions in emissions inventories. Coatings and solvent contributions from CMB were much lower than the proportions attributed to these sources in current emissions inventories. Several measurement and reporting conventions would facilitate CMB analyses of VOC data sets.
C Samara - One of the best experts on this subject based on the ideXlab platform.
-
an iterative method for evaluating the inter comparability between Chemical Mass Balance and multivariate receptor models
Chemometrics and Intelligent Laboratory Systems, 2016Co-Authors: G Argyropoulos, C Samara, E Diapouli, Kostas EleftheriadisAbstract:Abstract A comparative study between Chemical Mass Balance (CMB) and multivariate receptor modeling techniques was conducted. The study involved common application of Robotic Chemical Mass Balance (RCMB) and 2-dimensional Positive Matrix Factorization (PMF). A two-fold methodology was developed for Source Apportionment (SA) of reactive species, in order to address previous limitations of CMB models. The developed methodology (a) uses a detailed set of theoretical source profiles, taking into account secondary reactions that were not considered in CMB modelling until now, and (b) implements a Least Squares (LS) fitting method that iteratively readjusts the values of independent variables in the CMB fit, providing (for the first time, to our knowledge) CMB source profiles as output data, in which secondary transformations may be reflected. A straight-forward computational procedure named Factor Mapping (FM) was developed as well, for intercomparison between RCMB and PMF. The distinctive feature of FM is that similarity measures are used not just to compare the results of the two models, as in previous intercomparison exercises, but, moreover, to actively assist in the physical interpretation of PMF factors, thus minimizing user interference. The intercomparison between RCMB and PMF also involved an independent evaluation of each model's performance in reproducing ambient concentrations of particulate matter (PM) and associated Chemical constituents. Overall, it was shown that the employed series of computational steps substantially improve qualitative as well as quantitative agreement between the two models.
-
development and application of a robotic Chemical Mass Balance model for source apportionment of atmospheric particulate matter
Environmental Modelling and Software, 2011Co-Authors: Georgios Argyropoulos, C SamaraAbstract:An advanced computational procedure is presented for the source apportionment (SA) of airborne particulate matter (PM) using Chemical Mass Balance (CMB) receptor modeling. The so-called "Robotic Chemical Mass Balance" model (RCMB) minimizes personal judgment, by leading straight-forwardly to the best-fit combination of the source profiles that are included in a set of input data. RCMB involves application of an established least squares fitting method to every one of the possible combinations that can be made from the source profiles, without any human interference, in contrast with previous CMB modeling software. Any successful applications of the fitting method are automatically ranked according to performance measures, common in multiple linear regression (MLR). By maximizing an overall fitting index, the proposed computational procedure provides a unique solution to the conventional CMB problem, which cannot be questioned readily, unless additional information becomes available about the study area. This explicit advantage of RCMB is illustrated by a comparison with the original CMB analysis of the Crows, California PM2.5 data from the San Joaquin Valley Air Quality Study (SJVAQS).
-
Chemical Mass Balance source apportionment of tsp in a lignite burning area of western macedonia greece
Atmospheric Environment, 2005Co-Authors: C SamaraAbstract:Abstract Total suspended particle Mass concentrations (TSP) were determined in the Kozani-Ptolemais-Florina basin (western Macedonia, Greece), an area with intensive lignite burning for power generation. The study was conducted over a 1-year period (November 2000–November 2001) at 10 receptor sites located at variable distances from the power plants. Ambient TSP samples were analyzed for 27 major, minor and trace elements. Particulate emissions were also collected from a variety of sources including fly ash, lignite dust, automobile traffic, domestic heating, and open-air burning of agricultural bioMass and refuse, and analyzed for the same Chemical components. Ambient and source Chemical profiles were used for source identification and apportionment of TSP by employing a Chemical Mass Balance (CMB) receptor model. Diesel burning in vehicular traffic and in the power plants for generator start up was found to be the major contributor to ambient TSP levels at all 10 sites. Other sources with significant contributions were domestic coal burning, vegetative burning (wood combustion and agricultural burns) and refuse open-air burning. Fly ash escaping the electrostatic precipitators of the power plants was a minor contributor to ambient TSP.
-
Chemical Mass Balance source apportionment of pm10 in an industrialized urban area of northern greece
Atmospheric Environment, 2003Co-Authors: C Samara, Th Kouimtzis, R Tsitouridou, G Kanias, Vasil SimeonovAbstract:Ambient PM10 were sampled at three sites in an industrialized urban area of Northern Greece during June 1997–June 1998 and analyzed for 17 Chemical elements, 5 water-soluble ions and 13 polycyclic aromatic hydrocarbons. In addition, Chemical source profiles consisting of the same particulate components were obtained for a number of industrial activities (cement, fertilizer and asphalt production, quarry operations, metal electroplating, metal welding and tempering, steel manufacture, lead and bronze smelters, metal scrap incineration), residential oil burning, non-catalyst and catalyst-equipped passenger cars, diesel fuelled taxis and buses, as well as for geological fugitive sources (paved road dust and soil from open lands). Ambient and source data were used in a Chemical Mass Balance (CMB) receptor model for source identification and apportionment. Results of CMB modeling showed that major source of ambient PM10 at all three sites was diesel vehicle exhaust. Significant contribution from industrial oil burning was also evidenced at the site located closest to the industrial area.
Eric M Fujita - One of the best experts on this subject based on the ideXlab platform.
-
evaluations of the Chemical Mass Balance method for determining contributions of gasoline and diesel exhaust to ambient carbonaceous aerosols
Journal of The Air & Waste Management Association, 2007Co-Authors: Eric M Fujita, Judith C. Chow, David E Campbell, W P Arnott, Barbara ZielinskaAbstract:Abstract The US. Department of Energy Gasoline/Diesel PM Split Study was conducted to assess the sources of uncertainties in using an organic compound–based Chemical Mass Balance receptor model to quantify the relative contributions of emissions from gasoline (or spark ignition [SI]) and diesel (or compression ignition [CI]) engines to ambient concentrations of fine particulate matter (PM2.5) in California’s South Coast Air Basin (SOCAB). In this study, several groups worked cooperatively on source and ambient sample collection and quality assurance aspects of the study but worked independently to perform Chemical analysis and source apportionment. Ambient sampling included daily 24–hr PM2.5 samples at two air quality–monitoring stations, several regional urban locations, and along freeway routes and surface streets with varying proportions of automobile and truck traffic. Diesel exhaust was the dominant source of total carbon (TC) and elemental carbon (EC) at the Azusa and downtown Los Angeles, CA, monit...
-
review of volatile organic compound source apportionment by Chemical Mass Balance
Atmospheric Environment, 2001Co-Authors: John G. Watson, Judith C. Chow, Eric M FujitaAbstract:The Chemical Mass Balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the Chemical compounds used in the calculation, the apportionment units, and the source profiles applied. Nevertheless, they show similar results for VOC fractions contributed by different sources. Gasoline vehicle exhaust, liquid gasoline, and gasoline evaporation contribute up to 50% or more of the ambient VOCs in many of these studies. Relative motor vehicle source contributions determined by CMB were similar to or larger than their proportions in emissions inventories. Coatings and solvent contributions from CMB were much lower than the proportions attributed to these sources in current emissions inventories. Several measurement and reporting conventions would facilitate CMB analyses of VOC data sets.
-
validation of the Chemical Mass Balance receptor model applied to hydrocarbon source apportionment in the southern california air quality study
Environmental Science & Technology, 1994Co-Authors: Eric M Fujita, Judith C. Chow, John G. Watson, Zhiqiang LuAbstract:The non-methane hydrocarbon (NMHC) data base acquired during the Southern California Air Quality Study (SCAQS) was used to assess the performance of the Chemical Mass Balance (CMB) receptor model following the CMB applications and validation protocol. As a prelude to the actual CMB effective variance runs, initial source contribution estimates were made to determine the optimal combination of source profiles and fitting species. Several different source composition profiles were selected for major source types to determine the effect of alternative profiles on the source contribution estimates and on overall model performance. The ambient NMHC data were also examined by less complex tracer and bivariate regression methods to gain additional insights about probable source contributions, spatial and temporal patterns of emission sources, and photoChemical reactions of various hydrocarbon species. NMHC was apportioned to motor vehicle exhaust, liquid fuel, gasoline vapor, gas leaks, architectural and industrial coatings, and biogenic emissions. Attribution of source contributions among the motor vehicle source categories is highly sensitive to the abundance of ethyne and light olefins to NMHC in the exhaust composition profile, which varies with emission control technology and vehicle maintenance and operation. 51 refs., 2 figs., 9 tabs.
-
Chemical Mass Balance source apportionment of pm10 during the southern california air quality study
Aerosol Science and Technology, 1994Co-Authors: John G. Watson, Judith C. Chow, Eric M Fujita, Douglas H. Lowenthal, Zhiqiang Lu, Douglas R Lawson, Lowell L AshbaughAbstract:The Chemical Mass Balance (CMB) receptor model was applied to the Chemically speciated diurnal particulate matter samples acquired at nine locations in California's South Coast Air Basin (SoCAB) during the summer and fall of 1987 as part of the Southern California Air Quality Study (SCAQS). Source profiles applicable to the Los Angeles area were used to apportion PM2.5 and PM10 (particles with aerodynamic diameters < 2.5 and 10 μm, respectively) to primary paved road dust, primary construction dust, primary motor vehicle exhaust, primary marine aerosol, secondary ammonium nitrate, and secondary ammonium sulfate. Suspended dust was the major contributor to PM10 during the summer, whereas secondary ammonium nitrate and primary motor vehicle exhaust contributions were high during the fall. Secondary ammonium sulfate contributions were uniform across the SoCAB, with average contributions during the fall less than half those found during the summer. Marine aerosol contributions were lower during the fall than ...
Lowell L Ashbaugh - One of the best experts on this subject based on the ideXlab platform.
-
Chemical Mass Balance source apportionment of pm10 during the southern california air quality study
Aerosol Science and Technology, 1994Co-Authors: John G. Watson, Judith C. Chow, Eric M Fujita, Douglas H. Lowenthal, Zhiqiang Lu, Douglas R Lawson, Lowell L AshbaughAbstract:The Chemical Mass Balance (CMB) receptor model was applied to the Chemically speciated diurnal particulate matter samples acquired at nine locations in California's South Coast Air Basin (SoCAB) during the summer and fall of 1987 as part of the Southern California Air Quality Study (SCAQS). Source profiles applicable to the Los Angeles area were used to apportion PM2.5 and PM10 (particles with aerodynamic diameters < 2.5 and 10 μm, respectively) to primary paved road dust, primary construction dust, primary motor vehicle exhaust, primary marine aerosol, secondary ammonium nitrate, and secondary ammonium sulfate. Suspended dust was the major contributor to PM10 during the summer, whereas secondary ammonium nitrate and primary motor vehicle exhaust contributions were high during the fall. Secondary ammonium sulfate contributions were uniform across the SoCAB, with average contributions during the fall less than half those found during the summer. Marine aerosol contributions were lower during the fall than ...