Showing papers on "Particulates published in 2001"
920 citations
TL;DR: In this paper, the experimental techniques which have been used to study the gasification of soot are described and the methods and results obtained by analysis of the data from them are considered.
796 citations
TL;DR: In this paper, the authors focus on the number of particles and the characteristics of them (size, composition) rather than the mass of the particles and their characteristics have a higher impact on health.
Abstract: During the last few decades, concerns have grown on the negative effects that diesel particulate matter has on health. Because of this, particulate emissions were subjected to restrictions and various emission-reduction technologies were developed. It is ironic that some of these technologies led to reductions in the legislated total particulate mass while neglecting the number of particles. Focusing on the mass is not necessarily correct, because it might well be that not the mass but the number of particles and the characteristics of them (size, composition) have a higher impact on health. To eliminate the threat of diesel particulate matter, essentially absolute filtration in combination with the oxidation of all emitted hydrocarbons is what will be required. After two decades of development, the first filters will soon be introduced on a large scale. Many different problems had to be overcome; it was especially important that the filter was robust and its regeneration was controllable. The key technol...
509 citations
TL;DR: In this article, the mass concentrations of the two fractions showed significant daily variations linked to different thermodynamic conditions of the planetary boundary layer (PBL) and characterised by higher values during wintertime.
508 citations
TL;DR: The analysis of PM10 and TSP levels recorded in rural areas from Southern and Eastern Spain (1996-1999) shows that most of the peak events are simultaneously recorded at monitoring stations up to 1000 km apart as mentioned in this paper.
505 citations
TL;DR: It is hypothesized that semiquinone radicals in PM(2.5) undergo redox cycling, thereby reducing oxygen and generating reactive oxygen species while consuming tissue-reducing equivalents, such as NAD(P)H and ascorbate, which cause oxidative stress at sites of deposition and produce deleterious effects observed in the lung.
452 citations
TL;DR: In this article, the size distributions of diesel exhaust particulate matter measured from a large number of vehicles and test engines, using a variety of diesel fuels, collapse onto a single characteristic lognormal distribution, when normalized by total particle number and plotted against a scaled diameter.
449 citations
TL;DR: It is suggested that organic matter might be protected from degradation by the inorganic matrix of sinking particles, and that amino-acid-like material predominates throughout the water column in both regions of the Pacific Ocean and the Arabian Sea.
Abstract: The sinking of particulate organic matter from ocean surface waters transports carbon to the ocean interior1,2, where almost all is then recycled. The unrecycled fraction of this organic matter can become buried in ocean sediments, thus sequestering carbon and so influencing atmospheric carbon dioxide concentrations3. The processes controlling the extensive biodegradation of sinking particles remain unclear, partly because of the difficulty in resolving the composition of the residual organic matter at depth with existing chromatographic techniques4. Here, using solid-state 13C NMR spectroscopy5, we characterize the chemical structure of organic carbon in both surface plankton and sinking particulate matter from the Pacific Ocean4 and the Arabian Sea6. We found that minimal changes occur in bulk organic composition, despite extensive (>98%) biodegradation, and that amino-acid-like material predominates throughout the water column in both regions. The compositional similarity between phytoplankton biomass and the small remnant of organic matter reaching the ocean interior indicates that the formation of unusual biochemicals, either by chemical recombination7 or microbial biosynthesis8, is not the main process controlling the preservation of particulate organic carbon within the water column at these two sites. We suggest instead that organic matter might be protected from degradation by the inorganic matrix of sinking particles.
345 citations
TL;DR: In this article, the authors used a model in which the immediate effect of a decrease in global marine calcification relative to POC production on the potential capacity for oceanic CO2 uptake was simulated, assuming that overall marine biogenic calcification shows a similar response as obtained for E. huxleyi or G. oceanica in the present study.
Abstract: In laboratory experiments with the coccolithophore species Emiliania huxleyi and Gephyrocapsa oceanica, the ratio of particulate inorganic carbon (PIC) to particulate organic carbon (POC) production decreased with increasing CO2 concentration ([CO2]). This was due to both reduced PIC and enhanced POC production at elevated [CO2]. Carbon dioxide concentrations covered a range from a preindustrial level to a value predicted for 2100 according to a “business as usual” anthropogenic CO2 emission scenario. The laboratory results were used to employ a model in which the immediate effect of a decrease in global marine calcification relative to POC production on the potential capacity for oceanic CO2 uptake was simulated. Assuming that overall marine biogenic calcification shows a similar response as obtained for E. huxleyi or G. oceanica in the present study, the model reveals a negative feedback on increasing atmospheric CO2 concentrations owing to a decrease in the PIC/POC ratio.
339 citations
TL;DR: In this paper, climate change may affect exposures to air pollutants by affecting weather, anthropogenic emissions, and biogenic emissions and by changing the distribution and types of airborne allergens, but the specific types of change (i.e., local, regional, or global), the direction of change in a particular location, and the magnitude of change that may be attributable to climate change are a matter of speculation, based on extrapolating present understanding to future scenarios.
Abstract: Climate change may affect exposures to air pollutants by affecting weather, anthropogenic emissions, and biogenic emissions and by changing the distribution and types of airborne allergens. Local temperature, precipitation, clouds, atmospheric water vapor, wind speed, and wind direction influence atmospheric chemical processes, and interactions occur between local and global-scale environments. If the climate becomes warmer and more variable, air quality is likely to be affected. However, the specific types of change (i.e., local, regional, or global), the direction of change in a particular location (i.e., positive or negative), and the magnitude of change in air quality that may be attributable to climate change are a matter of speculation, based on extrapolating present understanding to future scenarios. There is already extensive evidence on the health effects of air pollution. Ground-level ozone can exacerbate chronic respiratory diseases and cause short-term reductions in lung function. Exposure to particulate matter can aggravate chronic respiratory and cardiovascular diseases, alter host defenses, damage lung tissue, lead to premature death, and possibly contribute to cancer. Health effects of exposures to carbon monoxide, sulfur dioxide, and nitrogen dioxide can include reduced work capacity, aggravation of existing cardiovascular diseases, effects on pulmonary function, respiratory illnesses, lung irritation, and alterations in the lung's defense systems. Adaptations to climate change should include ensuring responsiveness of air quality protection programs to changing pollution levels. Research needs include basic atmospheric science work on the association between weather and air pollutants; improving air pollution models and their linkage with climate change scenarios; and closing gaps in the understanding of exposure patterns and health effects.
289 citations
TL;DR: In this article, a methodology based on PM2.5 measurement alone is not adequate for monitoring the impact of primary particulate emissions (such as ceramic emissions) on air quality, since the major ambient air particles derived from these emissions are mainly in the range of 2.5-10μm.
TL;DR: A population exposure model for particulate matter (PM), called the Stochastic Human Exposure and Dose Simulation (SHEDS-PM) model, has been developed and applied in a case study of daily PM2.5 exposures for the population living in Philadelphia, PA, suggesting that human activity patterns did not have as strong an influence on ambient PM 2.5 exposure patterns as was observed for exposure to other PM1.5 sources.
Abstract: A population exposure model for particulate matter: case study results for PM 2.5 in Philadelphia, PA
TL;DR: In this paper, an analysis of continuous simultaneous measurement data for PM 10 and PM 2.5 using TEOM instruments from five sites in the United Kingdom is presented, where the results are analyzed specifically in relation to the sources and processes influencing the coarse particle fraction (2.5-10μm).
TL;DR: In this subtropical city, local air quality objectives should take into account that air pollution has stronger health effects during the cool rather than warm season and that oxidant pollutants are more important indicators of health effects than particulates.
Abstract: In different weather conditions, constituents and concentrations of pollutants, personal exposure, and biologic responses to air pollution may vary. In this study we assessed the effects of four air pollutants on mortality in both cool and warm seasons in Hong Kong, a subtropical city. Daily counts of mortality, due to all nonaccidental causes, and cardiovascular and respiratory diseases were modeled with daily pollutant concentrations [24-hr means for nitrogen dioxide, sulfur dioxide, and particulate matter 0.135). In this subtropical city, local air quality objectives should take into account that air pollution has stronger health effects during the cool rather than warm season and that oxidant pollutants are more important indicators of health effects than particulates.
TL;DR: In this article, a detailed aerosol source apportionment study was performed with two sampling campaigns, during wintertime and summertime in the heavily polluted metropolitan area of S* ao Paulo, Brazil.
TL;DR: A need exists for a comprehensive investigation of the human health-related aspects of exposure to particulates and PAHs in the urban environment.
Abstract: Airborne suspended particulate matter is an important marker of air quality. The term 'particulates' includes organic and inorganic matter, nitrogen compounds, sulphur compounds, polycyclic aromatic hydrocarbons (PAHs), several heavy metals, and radionuclides. The health risks from the 'classic' pollutants sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, and particulates have been comprehensively reviewed. Alarming levels of non-classic pollutants like the PAHs have been reported globally. PAHs have been found in placental tissues of women and in umbilical cord blood samples from newborn babies. The damaged DNA in cord blood is a indication of the fate of these pollutants in the environment. Hence, a need exists for a comprehensive investigation of the human health-related aspects of exposure to particulates and PAHs in the urban environment. This paper reviews the literature on PAHs in conjunction with particulate matter on a global perspective.
TL;DR: In this paper, the evolution of sea-salt and dust particles in East Asia is investigated using a three-dimensional transport and chemistry model, and a kinetic approach under thermodynamic constraint is utilized to model the condensation/evaporation processes, and other important aerosol processes and influential components are taken into account in this analysis.
Abstract: The evolution of sea-salt and dust particles in East Asia is investigated using a three-dimensional transport and chemistry model. A kinetic approach under thermodynamic constraint is utilized to model the condensation/evaporation processes, and other important aerosol processes and influential components (e.g., dust/sea-salt generation, NH3 emissions, gravitational settling, nucleation) are taken into account in this analysis. The model is used to study the Pacific Exploratory Mission-West B period (March 1–6, 1994). It is found that (1) during strong continental outflow, in general, the fine aerosol mode ( 2 μm in aerodynamic diameter) attracts nitrate. However, in the dust plume, sulfate preferentially resides in the coarse mode due to larger coarse mode mass loading; (2) particulate nitrate coupled with particulate ammonium in the fine mode is predicted over regions where high gaseous NH3 mixing ratios are present (lower courses of the Huang river); (3) dust and sea-salt particles provide important reaction surfaces for sulfate production in the troposphere and increase sulfate production rates by 20–80%; and (4) soil dust and sea salt provide an important source of boundary layer and free troposhpere alkaline material, and these cations play an important role in controlling the partitioning of semivolatile HNO3 throughout large portions of the troposphere, increasing particulate nitrate levels 10–50%.
TL;DR: Transformation and remineralization of freshly produced particulate organic matter by aggregate-attached food web is significant and the vertical flux of particulates organic matter in the ocean is highly reduced during sedimentation.
Abstract: The major pathways of transformation of particulate organic matter by heterotrophic bacteria are respiration and production of new biomass. Until today only a limited number of studies have measured simultaneously respiration and production by aggregate-associated bacteria. To study their role in the carbon cycle of aquatic systems we have formed model particles from diatoms (Skeletonema costatum, Thalasiosira weissflogii, Chaetoceros debilis) in roller tanks filled with natural seawater from Oresund, Denmark. Changes in bacterial community structure were analyzed by in situ hybridization and revealed members of the Cytophaga/Flavobacterium cluster and of the g subclass of Proteobacteria to be the main actors. The combination of radiotracer and microsensor techniques allowed determination of bacterial protein production and community respiration on the same aggregate and hence the apparent growth efficiency. Apparent growth efficiency (bacterial production/[bacterial production 1 community respiration]) was 0.50 ± 0.03 (se) on 1.5–2.5 d old aggregates and independent of bacterial growth rate. The initial carbon-specific bacterial production and community respiration was 0.082 d-1 and 0.084 d-1, respectively. Thereafter, the carbon-specific bacterial production decreased to 0.020 d-1, whereas specific community respiration decreased to 0.057 d-1. Hence, the apparent net growth efficiency decreased, partly as a result of grazing by protozoa, and it was much lower (0.23 ±; 0.04) at the end of incubation. Bacterial production was best correlated to particulate amino acids, whereas community respiration was best correlated to particulate organic carbon (POC). Protease activity was correlated to bacterial production and particulate combined amino acid content, whereas b-glucosidase activity was better correlated to POC and community respiration than to particulate combined amino acid content. Turnover times of radiolabeled amino acids increased from 17.8 to 1,190 h during incubation and were tightly coupled to particulate combined amino acids and POC. Eighty-seven percent of the decrease in particulate organic nitrogen (PON) over time could be explained by turnover of particulate combined amino acids by aggregate-associated food web. Thus, transformation and remineralization of freshly produced particulate organic matter by aggregate-attached food web is significant and the vertical flux of particulate organic matter in the ocean is highly reduced during sedimentation.
TL;DR: Carbon black is distinctly different from soot, and when discussing potential health effects, care must be taken to differentiate between the two types of carbon-based particles.
Abstract: Carbon blacks are manufactured under controlled conditions for commercial use primarily in the rubber, painting, and printing industries. In contrast, soots are unwanted byproducts from the combustion of carbon-based materials for the generation of energy or heat, or for the disposal of waste. Unfortunately, the terms carbon black and soot often have been used interchangeably; however, carbon black is physically and chemically distinct from soot. Greater than 97% of carbon black consists of elemental carbon arranged as aciniform particulate. Depending on the type of soot, the relative amount of carbon (<60% of the total particle mass), the type of particulate carbon, and particle characteristics (size, shape, and heterogeneity) can vary considerably. For both carbon black and soot, other elements and chemical compounds are associated with the particulate carbon. Total inorganics (ash) represent <1% of the carbon black particle mass. Organic compounds can be extracted from particle surfaces (solvent extrac...
TL;DR: In this paper, the authors collected aerosol was analyzed in relation to black and organic carbon content, showing that dispersion and dry deposition into the forest canopy were more important during the transport of the air masses than aerosol production by condensation and photochemical reactions.
TL;DR: Particulate matter emissions from the California in-use vehicle fleet were measured as 37,500 vehicles traveled through two bores of the Caldecott Tunnel located in the San Francisco Bay area to determine the particle chemical composition as a function of particle size.
Abstract: Particulate matter emissions from the California in-use vehicle fleet were measured as 37 500 vehicles traveled through two bores of the Caldecott Tunnel located in the San Francisco Bay area. Microorifice cascade impactors and filter-based samplers were used to determine the particle chemical composition as a function of particle size. Ammonia emissions from the vehicle fleet were measured as well. Concentrations of aerosol mass, organic carbon, elemental carbon, sulfate ion, nitrate ion, and ammonium ion, as well as 13 elements are reported. The particle mass distribution peaks in the particle size range 0.1−0.18 μm aerodynamic diameter (D_a). Elemental carbon and organic matter were the largest components of particle mass in all the size ranges studied. The Caldecott Tunnel bores studied include one which carries light-duty vehicle traffic and one which carries a mixture of light- and heavy-duty vehicle traffic. From experiments conducted in both bores, estimates are made of the size distribution and chemical composition of particulate matter emissions extrapolated to the 100% light-duty and 100% heavy-duty vehicle fleets. The heavy-duty vehicle fleet emitted 1285 ± 237 mg of fine particulate matter (D_a < 1.9 μm)/kg of C contained in the fuel burned (corresponding to approximately 430 ± 79 mg/km driven). Light-duty vehicles emitted less than 85 ± 6 mg/kg of C in the fuel burned (corresponding to less than approximately 5.5 ± 0.4 mg/km driven). Emissions of gas-phase ammonia in the Caldecott Tunnel were measured to be 194 and 267 mg/L of gasoline-equivalent fuel burned in the tunnel. The ammonia emissions are attributed to automobiles that were equipped with 3-way catalysts and operating fuel rich.
TL;DR: In this paper, the concentrations of semi-volatile polycyclic aromatic hydrocarbons (PAHs), hydro-carbons, HCs, particulate matter (PM 1, 2.5 and 10 μm), and total suspended particles (TSPs) were measured in a tra...
TL;DR: Mercury was the most strongly retained within the watershed for most of the rivers sampled, consistent with the tendency of this metal to bind strongly to particulate matter.
TL;DR: In this article, the authors used principal component factor analysis (PCFA) to identify and quantify aerosol sources using TSP (total suspended particulate matter), PM2−10 and PM2 (particulate matter with aerodynamic diameters from 2 to 10μm and less than 2μm, respectively) in Ho Chi Minh City.
TL;DR: In this article, the occurrence of selected nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) associated with atmospheric particulate matter has been investigated at an urban site and at a semi-rural site.
TL;DR: The MK1 fuel was found to be more environmentally friendly than the EPEFE fuel, which is the reference diesel fuel used in the "European Program on Emissions, Fuels and Engine Technologies" (EPEFE).
Abstract: Diesel fuels, classified as environmentally friendly, have been available on the Swedish market since 1991. The Swedish diesel fuel classification is based upon the specification of selected fuel composition and physical properties to reduce potential environmental and health effects from direct human exposure to exhaust. The objective of the present investigation was to compare the most stringent, environmentally classified Swedish diesel fuel (MK1) to the reference diesel fuel used in the "European Program on Emissions, Fuels and Engine Technologies" (EPEFE) program. The study compares measurements of regulated emissions, unregulated emissions, and biological tests from a Volvo truck using these fuels. The regulated emissions from these two fuels (MK1 vs EPEFE) were CO (-2.2%), HC (12%), NOx (-11%), and particulates (-11%). The emissions of aldehydes, alkenes, and carbon dioxide were basically equivalent. The emissions of particle-associated polycyclic aromatic hydrocarbons (PAHs) and 1-nitropyrene were 88% and 98% lower than those of the EPEFE fuel, respectively. The emissions of semi-volatile PAHs and 1-nitropyrene were 77% and 80% lower than those from the EPEFE fuel, respectively. The reduction in mutagenicity of the particle extract varied from -75 to -90%, depending on the tester strain. The reduction of mutagenicity of the semi-volatile extract varied between -40 and -60%. Furthermore, the dioxin receptor binding activity was a factor of 8 times lower in the particle extracts and a factor of 4 times lower in the semi-volatile extract than that of the EPEFE fuel. In conclusion, the MK1 fuel was found to be more environmentally friendly than the EPEFE fuel.
Patent•
27 Mar 2001TL;DR: In this paper, a device for purifying the exhaust gas of an internal combustion engine is described, which has a particulate filter arranged in the exhaust system on which the trapped particulates are oxidized, and a reversing mechanism for reversing the exhaust gases upstream side and downstream side of the filter so that the first trapping surface and second trapping surface are used alternately to trap the particulates.
Abstract: A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device has a particulate filter arranged in the exhaust system on which the trapped particulates are oxidized, and a reversing mechanism for reversing the exhaust gas upstream side and the exhaust gas downstream side of the particulate filter. The particulate filter has a trapping wall. The trapping wall has a first trapping surface and a second trapping surface. The reversing mechanism reverses the exhaust gas upstream side and the exhaust gas downstream side of the particulate filter so that the first trapping surface and the second trapping surface are used alternately to trap the particulates. The device can improve the amount of particulates that can be oxidized and removed on the particulate filter.
TL;DR: Magnetic hysteresis parameters were measured for three sample sets of respirable atmospheric particulate matter collected in Munich, Germany, and were compared with pollution data and meteorological data using principal component analysis.
TL;DR: The current status of the mathematical modeling of atmospheric particulate matter (PM) is reviewed and 11 3-dimensional Eulerian air quality models for PM are reviewed in terms of their formulation and past applications.
Abstract: The current status of the mathematical modeling of atmospheric particulate matter (PM) is reviewed in this paper. Simulating PM requires treating various processes, including the formation of condensable species, the gas/ particle partitioning of condensable compounds, and in some cases, the evolution of the particle size distribution. The algorithms available to simulate these processes are reviewed and discussed. Eleven 3-dimensional (3-D) Eulerian air quality models for PM are reviewed in terms of their formulation and past applications. Results of past performance evaluations of 3-D Eulerian PM models are presented. Currently, 24-hr average PM2.5 concentrations appear to be predicted within 50% for urban-scale domains. However, there are compensating errors among individual particulate species. The lowest errors tend to be associated with SO4 2-, while NO3 -, black carbon (BC), and organic carbon (OC) typically show larger errors due to uncertainties in emissions inventories and the predictio...
TL;DR: The presence of these tracers in atmospheric particulate matter over the ocean confirms the long-range transport of smoke from biomass burning off the continents.