Showing papers on "Particulates published in 2002"

Riverine composition and estuarine geochemistry of particulate metals in China-weathering features, anthropogenic impact and chemical fluxes

Abstract: Suspended sediments from large and middle size Chinese estuaries, including the Yalujiang, Shuangtaizihe, Luanhe, Jiaojiang and Zhujiang, were analysed to understand trace metal transport in the coastal zone. The determinations of 13 major and trace elements plus organic carbon were made of total concentrations and were fully validated by certified reference materials (CRMs). The combination of the data sets with other Chinese estuaries, such as Changjiang and Huanghe, provides an overview of particulate trace metal geochemistry in this region. Trace metal levels in Chinese rivers are relatively low compared with those draining industrialized regions of Europe and North America. In the estuaries, most particulate elements illustrate stable distribution in the mixing zone until a salinity of 30, especially when absolute concentrations are normalized to aluminium, although the total suspended matter (TSM) is quite different in time and space. Using Al as a reference, it was estimated that 25–40% for Cu, and 5–20% for Pb could remain in labile part in the Jiaojiang, Shuangtaizihe and Zhujiang, whereas different features of labile elements were found in the Changjiang and Luanhe. The mean enrichment factor (EFm) increases with higher sewage to river runoff ratio (S/R) over the drainage basin and EFm for suspended matter is higher than that for bottom sediments. Finally, inputs of particulate trace metals to the coast are estimated based on the riverine sediment load and chemical compositions.

Control of fossil‐fuel particulate black carbon and organic matter, possibly the most effective method of slowing global warming

Abstract: Under the 1997 Kyoto Protocol, no control of black carbon (BC) was considered. Here, it is found, through simulations in which 12 identifiable effects of aerosol particles on climate are treated, that any emission reduction of fossil-fuel (f.f.) particulate BC plus associated organic matter (OM) may slow global warming more than may any emission reduction of CO 2 or CH 4 for a specific period. When all f.f. BC + OM and anthropogenic CO 2 and CH 4 emissions are eliminated together, the period is 25-100 years. It is also estimated that historical net global warming can be attributed roughly to greenhouse gas plus f.f. BC + OM warming minus substantial cooling by other particles. Eliminating all f.f. BC + OM could eliminate 20-45% of net warming (8-18% of total warming before cooling is subtracted out) within 3-5 years if no other change occurred. Reducing CO 2 emissions by a third would have the same effect, but after 50-200 years. Finally, diesel cars emitting continuously under the most recent U.S. and E.U. particulate standards (0.08 g/mi; 0.05 g/km) may warm climate per distance driven over the next 100+ years more than equivalent gasoline cars. Thus, fuel and carbon tax laws that favor diesel appear to promote global warming. Toughening vehicle particulate emission standards by a factor of 8 (0.01 g/ mi; 0.006 g/km) does not change this conclusion, although it shortens the period over which diesel cars warm to 13-54 years. Although control of BC + OM can slow warming, control of greenhouse gases is necessary to stop warming. Reducing BC + OM will not only slow global warming but also improve human health.

Chapter 3 – Chemical Composition and Reactivity

Abstract: Oceans are the largest reservoirs of reactive organic carbon on the Earth. Most (97%) of the organic carbon in seawater resides in the operationally defined dissolved phase. The separation of the particulate and dissolved phases is most commonly accomplished by the passage of water samples through filters with pore sizes in the range 0.2–1.0 μm. During the past decade, it has become increasingly common to avoid the filtration of open ocean water samples for the separation of the particulate and dissolved phases. Filtration is often omitted because particulate organic carbon (POC) is a small fraction of the total organic carbon and the extra handling and processing of water samples during filtration aboard ship can lead to contamination. Concentrations of organic carbon, nitrogen, and phosphorus in unfiltered water samples are referred to as total organic concentrations (TOC, TON, and TOP respectively). Relatively small volumes (milliliters) of seawater are analyzed for these measurements and larger particles are not represented in these samples. Thus, the term “total” is somewhat of a misnomer for these analyses. In this chapter the data gathered on the concentrations and chemical composition of marine DOM includes some samples that were not filtered prior to the analysis. These samples come from the open ocean and the contribution of particulate organic matter (POM) to the reported data is considered to be minimal. In some cases, data for both filtered and unfiltered samples were available and the differences among these samples were often within the error of the measurement.

Chemical analysis of World Trade Center fine particulate matter for use in toxicologic assessment.

Abstract: The catastrophic destruction of the World Trade Center (WTC) on 11 September 2001 caused the release of high levels of airborne pollutants into the local environment. To assess the toxicity of fine particulate matter [particulate matter with a mass median aerodynamic diameter < 2.5 microm (PM2.5)], which may adversely affect the health of workers and residents in the area, we collected fallen dust samples on 12 and 13 September 2001 from sites within a half-mile of Ground Zero. Samples of WTC dust were sieved, aerosolized, and size-separated, and the PM2.5 fraction was isolated on filters. Here we report the chemical and physical properties of PM2.5 derived from these samples and compare them with PM2.5 fractions of three reference materials that range in toxicity from relatively inert to acutely toxic (Mt. St. Helens PM; Washington, DC, ambient air PM; and residual oil fly ash). X-ray diffraction of very coarse sieved WTC PM (< 53 microm) identified calcium sulfate (gypsum) and calcium carbonate (calcite) as major components. Scanning electron microscopy confirmed that calcium-sulfur and calcium-carbon particles were also present in the WTC PM2.5 fraction. Analysis of WTC PM2.5 using X-ray fluorescence, neutron activation analysis, and inductively coupled plasma spectrometry showed high levels of calcium (range, 22-33%) and sulfur (37-43% as sulfate) and much lower levels of transition metals and other elements. Aqueous extracts of WTC PM2.5 were basic (pH range, 8.9-10.0) and had no evidence of significant bacterial contamination. Levels of carbon were relatively low, suggesting that combustion-derived particles did not form a significant fraction of these samples recovered in the immediate aftermath of the destruction of the towers. Because gypsum and calcite are known to cause irritation of the mucus membranes of the eyes and respiratory tract, inhalation of high doses of WTC PM2.5 could potentially cause toxic respiratory effects.

The effects of the catalytic converter and fuel sulfur level on motor vehicle particulate matter emissions: light duty diesel vehicles.

Abstract: Wind tunnel measurements and direct tailpipe particulate matter (PM) sampling are utilized to examine how the combination of oxidation catalyst and fuel sulfur content affects the nature and quantity of PM emissions from the exhaust of a light duty diesel truck. When low sulfur fuel (4 ppm) is used, or when high sulfur (350 ppm) fuel is employed without an active catalyst present, a single log-normal distribution of exhaust particles is observed with a number mean diameter in the range of 70−83 nm. In the absence of the oxidation catalyst, the high sulfur level has at most a modest effect on particle emissions (<50%) and a minor effect on particle size (<5%). In combination with the active oxidation catalyst tested, high sulfur fuel can lead to a second, nanoparticle, mode, which appears at ∼20 nm during high speed operation (70 mph), but is not present at low speed (40 mph). A thermodenuder significantly reduces the nanoparticle mode when set to temperatures above ∼200 °C, suggesting that these particles...

Primary particle emissions from residential coal burning: Optical properties and size distributions

Abstract: [1] Particles generated by combustion of fossil fuels contribute to climate forcing by absorbing and scattering visible light. Residential combustion takes place in homes for heating or cooking purposes and is thought to contribute a large fraction of the global burden of anthropogenic primary particles. We present optical properties and size distributions of particulate matter emitted from three types of coal burned in residential combustors: bituminous coal, hard coal briquettes, and lignite. Emissions from these coals differ significantly and can be partially explained by differences in coal composition. For bituminous coal, particulate matter emission factors are somewhat greater than those used in current emission inventories. We observe particles for which the light absorption is weak and has a strong spectral dependence. For hard coal briquettes and lignite, emitted light absorption is low, and based on our measurements, current inventories of light-absorbing aerosols significantly overestimate the contribution from these sources. Hard coal briquettes produce very few particles in the optically active size range. For all coals tested the size distributions required to represent the average of the emitted particles are broader than atmospheric size distributions, with geometric standard deviations between 2.2 and 3.0.

Methods of reducing or preventing particulate flow-back in wells

Abstract: Methods of reducing or preventing particulate flow-back in subterranean zones are provided. In accordance with the methods, a treating fluid having a mixture of reticulated foam fragments and particulate solids suspended therein is provided. The treating fluid is introduced into a subterranean zone and the mixture of the reticulated foam fragments and the particulate solids are deposited in the subterranean zone whereby the reticulated foam fragments retard or prevent the flow-back of the particulate solids and the transport of formation fines from the subterranean zone upon the flowing-back of fluid from the zone.

Nutrients and organic matter in a glacial river—floodplain system (Val Roseg, Switzerland)

Abstract: Nutrient and organic matter dynamics were evaluated for a glacial river‐floodplain system in the Swiss Alps (Val Roseg). Glacial melt water was the primary source of particulate organic and inorganic matter; hillslope groundwater was richest in DOC and SiO2; and pulses in dissolved nitrogen were identified during spring snowmelt. Calculations of temporal coherency revealed that hydrological processes within the catchment‐floodplain complex controlled nutrient and organic matter species along the main channel; however, local hydrological and/or biogeochemical processes played a major controlling role in most floodplain channels. DON and NO 3-N were the only variables that were in average significantly correlated across all sampling sites. Comparisons of measured concentrations and concentrations based on a two end member mixing model indicated that the floodplain served as a major sink for particulate phosphorous and suspended matter but was never a source for nutrients or organic matter. Annual areaspecific export rates from the Val Roseg catchment were 7.6 kg ha 21 yr

Sources and processes affecting levels and composition of atmospheric aerosol in the western Mediterranean

Abstract: [1] Airborne particulate composition in the western Mediterranean atmosphere was investigated by means of simultaneous sampling of PM10 (particulate matter <10 μm) at a rural site (Ebro basin) and an urban one (Barcelona) in eastern Spain in order to evaluate the natural and anthropogenic contributions. The major regional particulate pollutants were nitrate, sulfate, and carbonaceous aerosols, whereas sea salt and mineral dust accounted for the main natural contribution. Owing to the thermodynamic properties of nitrogenous species, the load of nitrate in PM10 attains a maximum in the cold season (30% of bulk PM10 as rural and urban means in winter and <15% in summer). Conversely, in summer, sulfate attains a maximum load in PM10 (15–35% of bulk PM10 in summer and 5–20% in winter at two sites). High-sulfate events in summer were associated with ozone episodes at the rural site, which suggests that photochemical processes play a significant role in the production of particulate pollutants. High mineral dust concentrations were simultaneously recorded at the two sites during African dust outbreaks, when the dust load accounted for 50–80% of bulk PM10 at the rural site and 20–45% at the urban site. Daily dust concentrations in the range 20–25 μg/m3 (40–50% of the daily EU limit value for PM10) are frequently recorded during these African events. Analysis of satellite observations and meteorology shows that African dust outbreaks occur over large areas in southern Europe and interferes with the monitoring of levels of anthropogenic PM10 aerosols regularly performed in the national air quality networks.

The transformation of outdoor ammonium nitrate aerosols in theindoor environment

Abstract: Recent studies associate particulate air pollution with adverse health effects; however, the exposure to indoor particles of outdoor origin is not well characterized, particularly for individual chemical species. In response to this, a field study in an unoccupied, single-story residence in Clovis, California has been conducted. Real-time particle monitors were used both outdoors and indoors to quantify PM2.5 nitrate, sulfate, and carbon. The results show that reduced indoor sulfate and carbon levels are primarily due to deposition and penetration losses. However, measured indoor ammonium nitrate levels were often observed to be at significantly lower levels than expected based solely on penetration and deposition losses. The additional reduction appears to be due to the transformation of ammonium nitrate into ammonia and nitric acid indoors, which are subsequently lost by deposition and sorption to indoor surfaces. The size of the effect is dependent upon factors such as temperature, relative humidity, and ventilation rate.

Quantifying assimilation of sewage-derived organic matter by riverine benthos

Abstract: Fresh waters worldwide receive substantial loadings of particulate organic waste from municipal sewage collection and treatment works. This material may transport a wide variety of particle-associated contaminants. Using stable isotopes of carbon and nitrogen, we detected the influence of a nearby primary sewage treatment plant on the benthic food web of a large temperate river. Despite the low concentration of wastewater and the absence of accumulated sediment, >60% of carbon and nitrogen in benthic organisms near the outfall was of sewage origin. This fraction is disproportionately high relative to the fraction of sewage-derived suspended particulate matter in the seston, suggesting preferential assimilation. Assimilation of sewage-derived particulate organic matter exposes benthos to high levels of contamination and may represent an important source of contaminants to higher trophic levels.

Urban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy

Abstract: [1] A comprehensive range of aerosol parameters was measured at an urban and a rural site in the Milan, Italy metropolitan region during summer smog events in summer 1998. Measurements were performed as part of the Pianura Padana Produzione di Ozono (PIPAPO) field campaign to determine the sensitivity of O3 production to NOX and volatile organic carbon concentrations at several ground stations. Primary aerosol parameters (i.e., direct emissions) such as aerosol black carbon showed a distinct diurnal variation with maxima at about 0000 and 0800 central European summer time (CEST), in contrast to secondary aerosol parameters such as sulfate and nitrate. Aerosol number size distributions were measured under ambient conditions as well as after conditioning with volatility and hygroscopicity systems. A mode at d = 20–30 nm in the number concentration was found at 0800 CEST and exhibited high volatility at 110°C (∼80% volume lost upon heating) but no hygroscopic behavior. Based on these measurements, small particles (d < 40 nm) are thought to consist mainly of hydrophobic particulate organic matter, rather than soot or H2SO4 aerosols. Two distinct hygroscopic modes with average growth factors d/d0 ∼ 1.02 and 1.21–1.28 were found for particles with dry (relative humidity of <30%) diameters d0 = 50–200 nm. Submicrometer aerosols exhibited lower volatility at the rural than at the urban site, which is attributed to additional particulate mass produced by secondary particle formation.

Concentration and emissions of ammonia and particulate matter in tunnel–ventilated broiler houses under summer conditions in texas

Abstract: Total suspended particulate (TSP) concentrations, ammonia (NH3) concentrations, and ventilation rates were measured in four commercial, tunnel–ventilated broiler houses in June through December of 2000 in Brazos County, Texas. TSP and NH3 concentrations ranged from 7,387 to 11,387 .g m–3 and 2.02 to 45 ppm, respectively. Ammonia concentration exhibited a correlation with the age of the birds. Mass median diameters (MMD) of the TSP samples were between 24.0 and 26.7 .m aerodynamic equivalent diameter. MMD increased with bird age. The mass fraction of PM10 in the TSP samples was between 2.72% and 8.40% with a mean of 5.94%. Ventilation rates were measured between 0.58 and 89 m3 s–1. Measured concentrations of PM10 and ammonia were multiplied by the measured ventilation rates to calculate emission rates for PM10 and ammonia. Ammonia emission rates varied from 38 to 2105 g hr–1. TSP emission rates and PM10 emission rates ranged from 7.0 to 1673 g hr–1 and 0.58 to 99 g hr–1, respectively. Emission rates for ammonia and particulate matter increased with the age of the birds. Most of the PM in the commercial broiler houses was large enough to be captured by the human or poultry respiratory system prior to being inhaled into the lungs.

Source apportionment of secondary airborne particulate matter in a polluted atmosphere

Abstract: Secondary airborne particulate matter formed from gas-phase pollutants contributes significantly to the most severe particulate air quality events that occur in the United States each year. In this study, a mechanistic air quality model is demonstrated that can predict source contributions to the size distribution of secondary airborne particulate matter. Calculations performed for a typical air quality episode in Southern California show that NOx released from diesel engines and catalyst-equipped gasoline engines account for the majority of the secondary particulate nitrate aerosol measured at inland locations. NH3 released from catalyst-equipped gasoline engines, farm animals, and residential sources account for the majority of the secondary particulate ammonium ion at inland locations in the region. When both tailpipe and road dust emissions are considered, transportation sources dominate the size distribution of total (primary plus secondary) airborne particulate matter in the South Coast Air Basin during the episode studied. These findings suggest that the public health risk associated with air pollution released from transportation sources is significant relative to other public health threats such as traffic accidents.

The Effect of Oxygenates on Diesel Engine Particulate Matter

Abstract: A summary is presented of experimental results obtained from a Cummins B5.9 175 hp, direct-injected diesel engine fueled with oxygenated diesel blends. The oxygenates tested were dimethoxy methane (DMM), diethyl ether, a blend of monoglyme and diglyme, and ethanol. The experimental results show that particulate matter (PM) reduction is controlled largely by the oxygen content of the blend fuel. For the fuels tested, the effect of chemical structure was observed to be small. Isotopic tracer tests with ethanol blends reveal that carbon from ethanol does contribute to soot formation, but is about 50% less likely to form soot when compared to carbon from the diesel portion of the fuel. Numerical modeling was carried out to investigate the effect of oxygenate addition on soot formation. This effort was conducted using a chemical kinetic mechanism incorporating n-heptane, DMM and ethanol chemistry, along with reactions describing soot formation. Results show that oxygenates reduce the production of soot precursors (and therefore soot and PM) through several key mechanisms. The first is due to the natural shift in pyrolysis and decomposition products. In addition, high radical concentrations produced by oxygenate addition promote carbon oxidation to CO and CO2, limiting carbon availability for soot precursor formation. Additionally, high radical concentrations (primarily OH) serve to limit aromatic ring growth and soot particle inception.

Sources of atmospheric carbonaceous particulate matter in Pittsburgh, Pennsylvania.

Abstract: The organic carbon (OC)/elemental carbon (EC) tracer method is applied to the Pittsburgh, PA, area to estimate the contribution of secondary organic aerosol (SOA) to the monthly average concentration of organic particulate matter (PM) during 1995. An emissions inventory is constructed for the primary emissions of OC and EC in the area of interest. The ratio of primary emissions of OC to those of EC ranges between 2.4 in the winter months and 1.0 in the summer months. A mass balance model and ambient measurements were used to assess the accuracy of the emissions inventory. It is estimated to be accurate to within 50%. The results from this analysis show a strong monthly dependence of the SOA contribution to the total organic PM concentration, varying from near zero during winter months to as much as 50% of the total OC concentration in the summer.

Livestock ammonia management and particulate-related health benefits.

Abstract: Agricultural operations are the largest source of ammonia emissions in the United States and contribute to the formation of ammonium nitrate and ammonium sulfate, two prevalent forms of fine particulate matter. Researchers have found an association between fine particulate matter and a variety of adverse healths effects, including premature mortality, chronic bronchitis, hospital admissions, and asthma attacks. Management practices that reduce ammonia emissions may decrease adverse health effects, resulting in significant economic benefits. We estimated the impact of a variety of emission controls, including diet optimization, alum, and incorporation of manure into the land. The results suggest that relatively modest management policies can have a significant impact on fine particulate formation in the atmosphere. Because of the heterogeneous nature of particulate matter, a key question is the importance of particulate matter size and composition. To the extent that ammonium nitrate and ammonium sulfate c...

Diesel Soot Oxidation with NO2: Engine Experiments and Simulations

Abstract: The diesel particulate filters (DPFs) technology has impressively advanced especially during the last years, driven by the interest in the reduction of automobile particulate emissions. This paper is concerned with the effect of NO2 as an active oxidation agent in the regeneration process of the soot accumulated in the particulate filter. Experiments at realistic conditions using a diesel engine equipped with a standard oxidation catalyst and a particulate filter are carried out at a wide range of operating conditions. These results are used to validate an already available mathematical model of the NO2-assisted regeneration phenomena in the particulate filter. The combined use of experimental and modeling results provides interesting conclusions regarding the significance and the chemistry of the reaction of soot with NO2. The advantages and drawbacks of such an approach compared to standard laboratory synthetic gas studies are discussed. The agreement between experimental and simulation results in terms...