Showing papers on "Particulates published in 2006"

Evolution of ozone, particulates, and aerosol direct radiative forcing in the vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model

Abstract: [1] A new fully coupled meteorology-chemistry-aerosol model is used to simulate the urban- to regional-scale variations in trace gases, particulates, and aerosol direct radiative forcing in the vicinity of Houston over a 5 day summer period. Model performance is evaluated using a wide range of meteorological, chemistry, and particulate measurements obtained during the 2000 Texas Air Quality Study. The predicted trace gas and particulate distributions were qualitatively similar to the surface and aircraft measurements with considerable spatial variations resulting from urban, power plant, and industrial sources of primary pollutants. Sulfate, organic carbon, and other inorganics were the largest constituents of the predicted particulates. The predicted shortwave radiation was 30 to 40 W m−2 closer to the observations when the aerosol optical properties were incorporated into the shortwave radiation scheme; however, the predicted hourly aerosol radiative forcing was still underestimated by 10 to 50 W m−2. The predicted aerosol radiative forcing was larger over Houston and the industrial ship channel than over the rural areas, consistent with surface measurements. The differences between the observed and simulated aerosol radiative forcing resulted from transport errors, relative humidity errors in the upper convective boundary layer that affect aerosol water content, secondary organic aerosols that were not yet included in the model, and uncertainties in the primary particulate emission rates. The current model was run in a predictive mode and demonstrates the challenges of accurately simulating all of the meteorological, chemical, and aerosol parameters over urban to regional scales that can affect aerosol radiative forcing.

Emissions of primary aerosol and precursor gases in the years 2000 and 1750 prescribed data-sets for AeroCom

Abstract: Inventories for global aerosol and aerosol precursor emissions have been collected (based on published inventories and published simulations), assessed and prepared for the year 2000 (present-day conditions) and for the year 1750 (pre-industrial conditions). These global datasets establish a comprehensive source for emission input to global modeling, when simulating the aerosol impact on climate with state-of-the-art aerosol component modules. As these modules stratify aerosol into dust, sea-salt, sulfate, organic matter and soot, for all these aerosol types global fields on emission strength and recommendations for injection altitude and particulate size are provided. Temporal resolution varies between daily (dust and sea-salt), monthly (wild-land fires) and annual (all other emissions). These datasets benchmark aerosol emissions according to the knowledge in the year 2004. They are intended to serve as systematic constraints in sensitivity studies of the AeroCom initiative, which seeks to quantify (actual) uncertainties in aerosol global modeling.

The Effects of Components of Fine Particulate Air Pollution on Mortality in California: Results from CALFINE

Abstract: ObjectiveSeveral epidemiologic studies provide evidence of an association between daily mortality and particulate matter < 2.5 μm in diameter (PM2.5). Little is known, however, about the relative e...

Characterization of metals emitted from motor vehicles.

Abstract: A systematic approach was used to quantify the metals present in particulate matter emissions associated with on-road motor vehicles. Consistent sampling and chemical analysis techniques were used to determine the chemical composition of particulate matter less than 10 microm in aerodynamic diameter (PM10*) and particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5), including analysis of trace metals by inductively coupled plasma mass spectrometry (ICP-MS). Four sources of metals were analyzed in emissions associated with motor vehicles: tailpipe emissions from gasoline- and diesel-powered vehicles, brake wear, tire wear, and resuspended road dust. Profiles for these sources were used in a chemical mass balance (CMB) model to quantify their relative contributions to the metal emissions measured in roadway tunnel tests in Milwaukee, Wisconsin. Roadway tunnel measurements were supplemented by parallel measurements of atmospheric particulate matter and associated metals at three urban locations: Milwaukee and Waukesha, Wisconsin, and Denver, Colorado. Ambient aerosol samples were collected every sixth day for one year and analyzed by the same chemical analysis techniques used for the source samples. The two Wisconsin sites were studied to assess the spatial differences, within one urban airshed, of trace metals present in atmospheric particulate matter. The measurements were evaluated to help understand source and seasonal trends in atmospheric concentrations of trace metals. ICP-MS methods have not been widely used in analyses of ambient aerosols for metals despite demonstrated advantages over traditional techniques. In a preliminary study, ICP-MS techniques were used to assess the leachability of trace metals present in atmospheric particulate matter samples and motor vehicle source samples in a synthetic lung fluid.

Photochemical reactions in the tropospheric aqueous phase and on particulate matter

Abstract: This paper is a tutorial review in the field of atmospheric chemistry. It describes some recent developments in tropospheric photochemistry in the aqueous phase and on particulate matter. The main focus is regarding the transformation processes that photochemical reactions induce on organic compounds. The relevant reactions can take place both on the surface of dispersed particles and within liquid droplets (e.g. cloud, fog, mist, dew). Direct and sensitised photolysis and the photogeneration of radical species are the main processes involved. Direct photolysis can be very important in the transformation of particle-adsorbed compounds. The significance of direct photolysis depends on the substrate under consideration and on the colour of the particle: dark carbonaceous material shields light, therefore protecting the adsorbed molecules from photodegradation, while a much lower protection is afforded for the light-shaded mineral fraction of particulate. Particulate matter is also rich in photosensitisers (e.g. quinones and aromatic carbonyls), partially derived from PAH photodegradation. These compounds can induce degradation of other molecules upon radiation absorption. Interestingly, substrates such as methoxyphenols, major constituents of wood-smoke aerosol, can also enhance the degradation of some sensitisers. Photosensitised processes in the tropospheric aqueous phase have been much less studied: it will be interesting to assess the photochemical properties of Humic-Like Substances (HULIS) that are major components of liquid droplets. The main photochemical sources of reactive radical species in aqueous solution and on particulate matter are hydrogen peroxide, nitrate, nitrite, and Fe(III) compounds and oxides. The photogeneration of hydroxyl radicals can be important in polluted areas, while their transfer from the gas phase and dark generation are usually prevailing on an average continental scale. The reactions involving hydroxyl radicals can induce very fast transformation of compounds reacting with •OH at a diffusion-controlled rate (1010 M−1 s−1), with time scales of an hour or less. The hydroxyl-induced reactivity in solution can be faster than in the gas phase, influencing the degradation kinetics of water-soluble compounds. Moreover, photochemical processes in fog and cloudwater can be important sources of secondary pollutants such as nitro-, nitroso-, and chloro-derivatives.

Chemical Composition and Sources of PM10 and PM2.5 Aerosols in Guangzhou, China

Abstract: Aerosol samples of PM10 and PM2.5 are collected in summertime at four monitoring sites in Guangzhou, China. The concentrations of organic and elemental carbons (OC/EC), inorganic ions, and elements in PM10 and PM2.5 are also quantified. Our study aims to: (1) characterize the particulate concentrations and associated chemical species in urban atmosphere (2) identify the potential sources and estimate their apportionment. The results show that average concentration of PM2.5 (97.54 μg m−3) in Guangzhou significantly exceeds the National Ambient Air Quality Standard (NAAQS) 24-h average of 65 μg m−3. OC, EC, Sulfate, ammonium, K, V, Ni, Cu, Zn, Pb, As, Cd and Se are mainly in PM2.5 fraction of particles, while chloride, nitrate, Na, Mg, Al, Fe, Ca, Ti and Mn are mainly in PM2.5-10 fraction. The major components such as sulfate, OC and EC account for about 70–90% of the particulate mass. Enrichment factors (EF) for elements are calculated to indicate that elements of anthropogenic origins (Zn, Pb, As, Se, V, Ni, Cu and Cd) are highly enriched with respect to crustal composition (Al, Fe, Ca, Ti and Mn). Ambient and source data are used in the multi-variable linearly regression analysis for source identification and apportionment, indicating that major sources and their apportionments of ambient particulate aerosols in Guangzhou are vehicle exhaust by 38.4% and coal combustion by 26.0%, respetively.

Measurements of emission factors for primary carbonaceous particles from residential raw-coal combustion in China

Abstract: [1] The emission factors (EFs) of particles and their carbonaceous fractions, including black carbon (BC) and organic carbon (OC), are measured for residential burning of coal-chunks. Nine types of coals with wide-ranged thermal maturities were used. Particulate emissions from coal-stove are collected on quartz fiber filters through a dilution sampling system and analyzed for BC and OC by thermal-optical method. The EFs of particulate matter, OC, and BC from bituminous coal burning are 16.77, 8.29, and 3.32 g/kg, respectively, on the basis of burned dry and ash-free (daf) coal mass. They were much higher than those of anthracites, which are 0.78, 0.04, and 0.004 g/kg, respectively. Annual emission inventories of particles, OC, and BC from household coal burning are also estimated based on the EFs and coal consumption. The results of the calculations are 917.8, 477.7, and 128.4 gigagrams (Gg) for total particles, OC, and BC emitted in China during the year 2000.

Lung Toxicity of Ambient Particulate Matter from Southeastern U.S. Sites with Different Contributing Sources: Relationships between Composition and Effects

Abstract: BackgroundExposure to air pollution and, more specifically, particulate matter (PM) is associated with adverse health effects. However, the specific PM characteristics responsible for biological ef...

Exhaust emission control system for internal combustion engine

Abstract: PROBLEM TO BE SOLVED: To provide an exhaust emission control system for an internal combustion engine capable of efficiently regenerating diesel particulate filter without exposing the diesel particulate filter under a high temperature condition. SOLUTION: The diesel particulate filter (DPF) is constructed by putting a solid electrolyte film between an anode 21 and a cathode 22. Particulate matter accumulated in the DPF is electrochemically removed by supplying exhaust gas and air to the anode 21 and the cathode 22. Consequently, since the DPF regeneration process can be performed at a temperature at which particulate matter suddenly burns by the propagation of combustion or lower, deterioration of DPF can be prevented. Also, since part of energy which particulate matter has can be electrochemically taken out, fuel economy can be improved. COPYRIGHT: (C)2007,JPO&INPIT

Sensitivity of global tropospheric ozone and fine particulate matter concentrations to climate change

Abstract: [1] An integrated global model of climate, tropospheric gas phase chemistry, and aerosols has been used to investigate the sensitivity of global ozone and fine particulate matter concentrations to climate change. Two simulations corresponding to present (1990s) and future (2050s) climates have been performed and compared. A future climate has been imposed using ocean boundary conditions corresponding to the Intergovernmental Panel on Climate Change SRES A2 scenario for the 2050s decade, resulting in an increase in the global annual average values of the surface air temperature by 1.7°C, the lower tropospheric specific humidity by 0.9 g H2O/kg air, and the precipitation by 0.15 mm d−1. Present-day anthropogenic emissions have been used in both simulations while climate-sensitive natural emissions were allowed to vary with the simulated climate. The tropospheric ozone burden in the future climate run decreased by 5%, and its lifetime decreased from 27.8 to 25.3 days. The tropospheric ozone change is driven primarily by increased ozone loss rates through ozone photolysis in the presence of water vapor, which on a global scale, more than compensate for the increased ozone chemical production associated with increased temperatures. At the model surface layer, over remote regions, ozone mixing ratios decreased by 1–3 ppbv, while polluted regions showed a relatively smaller decrease of 0–1 ppbv and increased by 1–5 ppbv in some cases. The global burdens and lifetimes of fine particulate matter species in the future climate run decreased by 2 to 18% because of increased wet deposition loss rates associated with increased precipitation. At the model surface layer, there are regions of decreases and increases in the concentrations of fine particulate matter species. The increased surface layer concentrations of some fine particulate matter species is primarily driven by lower regional-scale precipitation and increased secondary production, where applicable. The robustness of the predicted regional-scale changes for fine particulate matter species is strongly dependent upon the predicted regional-scale precipitation changes.

Measurements of emission factors for primary carbonaceous particles from residential raw-coal combustion in China - article no. L20815

Abstract: The emission factors (EFs) of particles and their carbonaceous fractions, including black carbon (BC) and organic carbon (OC), are measured for residential burning of coal-chunks Nine types of coals with wide-ranged thermal maturities were used Particulate emissions from coal-stove are collected on quartz fiber filters through a dilution sampling system and analyzed for BC and OC by thermal-optical method The EFs of particulate matter, OC, and BC from bituminous coal burning are 1677, 829, and 332 g/kg, respectively, on the basis of burned dry and ash-free (daf) coal mass They were much higher than those of anthracites, which are 078, 004, and 0004 g/kg, respectively Annual emission inventories of particles, OC, and BC from household coal burning are also estimated based on the EFs and coal consumption The results of the calculations are 9178, 4777, and 1284 gigagrams (Gg) for total particles, OC, and BC emitted in China during the year 2000

Comprehensive study of lead pollution in Shanghai by multiple techniques

Abstract: Aerosol samples of PM10 particulates were examined with particle-induced X-ray emission (PIXE and micro-PIXE ), inductively coupled plasma-mass spectrometry, and X-ray absorption fine structures (XAFS) to investigate atmospheric Pb concentrations and its chemical species and to decide the source assignment. From the elemental analyses, lead concentrations were averaged at 369 and 237 ng·m-3 in aerosol samples of PM10 collected from 19 monitor sites in Shanghai in the winter of 2002 and 2003, respectively. The XAFS results show that major chemical forms of the lead particulates are probably PbCl2, PbSO4, and PbO. A calculation of isotope ratio and chemical mass balance of the PM10 samples revealed that the atmospheric lead particulates in Shanghai in the two periods were mainly from coal combustors, iron and steel plants, and automobile exhausts, with coal combustion dominating the lead pollution after the phasing out of leaded gasoline in 1997 in Shanghai.

Characterization and identification of the sources of chromium, zinc, lead, cadmium, nickel, manganese and iron in PM10 particulates at the two sites of Kolkata, India.

Abstract: Monitoring of ambient PM10 (particulate matter which passes through a size selective impactor inlet with a 50% efficiency cut-off at 10 microm aerodynamic diameter) has been done at residential (Kasba) and industrial (Cossipore) sites of an urban region of Kolkata during November 2003 to November 2004. These sites were selected depending on the dominant anthropogenic activities. Metal constituents of atmospheric PM10 deposited on glass fibre filter paper were estimated using Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). Chromium (Cr), zinc (Zn), lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn) and iron (Fe) are the seven toxic trace metals quantified from the measured PM10 concentrations. The 24 h average concentrations of Cr, Zn, Pb, Cd, Ni, Mn and Fe from ninety PM10 particulate samples of Kolkata were found to be 6.9, 506.1, 79.1, 3.3, 7.4, 2.4 and 103.6 ng/m3, respectively. The 24 h average PM10 concentration exceeded national ambient air quality standard (NAAQS) as specified by central pollution control board, India at both residential (Kasba) and industrial (Cossipore) areas with mean concentration of 140.1 and 196.6 microg/m3, respectively. A simultaneous meteorology study was performed to assess the influence of air masses by wind speed, wind direction, rainfall, relative humidity and temperature. The measured toxic trace metals generally showed inverse relationship with wind speed, relative humidity and temperature. Factor analysis, a receptor modeling technique has been used for identification of the possible sources contributing to the PM10. Varimax rotated factor analysis identified four possible sources of measured trace metals comprising solid waste dumping, vehicular traffic with the influence of road dust, road dust and soil dust at residential site (Kasba), while vehicular traffic with the influence of soil dust, road dust, galvanizing and electroplating industry, and tanning industry at industrial site (Cossipore).

Size-resolved emissions of organic tracers from light- and heavy-duty vehicles measured in a California roadway tunnel.

Abstract: Individual organic compounds found in particulate emissions from vehicles have proven useful in source apportionment of ambient particulate matter. Species of interest include the hopanes, originating in lube oil, and selected PAHs generated via combustion. Most efforts to date have focused on emissions and apportionment PM10 or PM2.5 However, examining how these compounds are segregated by particle size in both emissions and ambient samples will help efforts to apportion size-resolved PM, especially ultrafine particles which have been shown to be more potent toxicologically. To this end, high volume size-resolved (coarse, accumulation, and ultrafine) PM samples were collected inside the Caldecott tunnel in Orinda, California to determine the relative emission factors for these compounds in different size ranges. Sampling occurred in two bores, one off-limits to heavy-duty diesel vehicles, which allows determination of the different emissions profiles for diesel and gasoline vehicles. Although tunnel measurements do not measure emissions over a full engine duty cycle, they do provide an average emissions profile over thousands of vehicles that can be considered characteristic of "freeway" emissions. Results include size-fractionated emission rates for hopanes, PAHs, elemental carbon, and other potential organic markers apportioned to diesel and gasoline vehicles. The results are compared to previously conducted PM2.5 emissions testing using dynamometer facilities and othertunnel environments.

The Impact of Energy, Transport, and Trade on Air Pollution in China

Abstract: A team of U.S.- and China-based geographers examines the relationship between China's economic development and its environment by modeling the effects of energy, transport, and trade on local air pollution emissions (sulfur dioxide and soot particulates) using the Environmental Kuznets model. Specifically, the latter model is investigated using spatial econometrics that take into account potential regional spillover effects from high-polluting neighbors. The analysis finds an inverted-U relationship for sulfur dioxide but a U-shaped curve for soot particulates. This suggests that soot particulates such as black carbon may pose a more serious environmental problem in China than sulfur dioxide. Journal of Economic Literature, Classification Numbers: C50, F10, Q43, R40. 4 figures, 3 tables, 47 references.