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Author: Toshihiro Kuwayama Publisher: ISBN: 9781321363104 Category : Languages : en Pages :
Book Description
Diesel and gasoline powered motor vehicle emissions were quantified through both ambient measurements and source-based emissions measurements. Ambient ultrafine particulate matter was measured and chemically speciated for a source apportionment analysis to identify the vehicular contributions at an urban city in California. The efforts of the Emissions Reduction Plan for Ports and Goods Movement in California have been realized through the comparison of ultrafine particulate matter contributions from old-technology diesel engines during different phases of the regulation implementation between years 2009 and 2010. Volatility of primary organic aerosols from gasoline powered motor vehicles was investigated using a series of thermodenuder experiments and particle evaporation modeling. The behaviors and the compositions of gas- and particle-phase motor vehicle emissions under atmospherically relevant conditions were also examined. These analyses will aid scientists and regulators in properly assessing the current state of vehicular emissions regulations, aid in particulate matter exposure studies, improve the understanding of the characteristics of vehicular emissions, and determine the effects of atmospheric parameters on the production and the partitioning of organic pollutants.
Author: Toshihiro Kuwayama Publisher: ISBN: 9781321363104 Category : Languages : en Pages :
Book Description
Diesel and gasoline powered motor vehicle emissions were quantified through both ambient measurements and source-based emissions measurements. Ambient ultrafine particulate matter was measured and chemically speciated for a source apportionment analysis to identify the vehicular contributions at an urban city in California. The efforts of the Emissions Reduction Plan for Ports and Goods Movement in California have been realized through the comparison of ultrafine particulate matter contributions from old-technology diesel engines during different phases of the regulation implementation between years 2009 and 2010. Volatility of primary organic aerosols from gasoline powered motor vehicles was investigated using a series of thermodenuder experiments and particle evaporation modeling. The behaviors and the compositions of gas- and particle-phase motor vehicle emissions under atmospherically relevant conditions were also examined. These analyses will aid scientists and regulators in properly assessing the current state of vehicular emissions regulations, aid in particulate matter exposure studies, improve the understanding of the characteristics of vehicular emissions, and determine the effects of atmospheric parameters on the production and the partitioning of organic pollutants.
Author: Timothy Ryan Dallmann Publisher: ISBN: Category : Languages : en Pages : 153
Book Description
Mobile sources contribute significantly to air pollution problems. Relevant pollutants include numerous gaseous and particle-phase species that can affect human health, ecosystems, and climate. Accurate inventories of emissions from these sources are needed to help understand possible adverse impacts, and to develop effective air quality management strategies. Unfortunately large uncertainties persist in the understanding of mobile source emissions, and how these emissions are changing over time. There are more than two hundred million motor vehicles operating in the United States alone, and measurements of emissions from these sources are sparse. Pollutant emission factor distributions are becoming increasingly skewed, and this continually increases the needed vehicle sample size in studies that seek to quantify fleet-average vehicle emission rates. This dissertation aims to evaluate long-term trends in mobile source emissions in the United States, and to make detailed measurements of emissions from present-day fleets of on-road vehicles operating in California. Novel features of this work include studies of the in-use effectiveness of modern control technologies used to reduce diesel engine emissions, and application of advanced instrumentation to measure emissions from large numbers of on-road gasoline and diesel vehicles at high time resolution and with a high level of chemical and physical detail. Long-term trends in mobile source emissions of nitrogen oxides (NOx) and fine particulate matter (PM2.5) in the United States were investigated through development of a fuel-based emission inventory. Annual emissions from on- and off-road gasoline and diesel engines were quantified for the years 1996-2006. Diesel engines were found to be the dominant mobile source of NOx and PM2.5, and on-road diesel vehicles were identified as the single largest anthropogenic source of NOx emissions in the United States as of 2005. The relative importance of diesel engines as a source of NOx grew over the ten-year time period considered here, while emissions from gasoline engines declined due to increased effectiveness and use of three-way catalytic converters. A comparison with national emission inventory estimates for 2005 found substantial differences in source contributions to overall mobile source emissions, with larger contributions from on-road diesel engines indicated in this study. The importance of diesel engines as a source of exhaust particulate matter emissions has led to the recent introduction of advanced emission control technologies in the United States, such as diesel particle filters (DPF), which have been required since 2007 for all new on-road heavy-duty (HD) diesel engines. In addition to national requirements for the use of such control devices on new engines, California has mandated accelerated clean-up of statewide emissions from older in-use diesel engines. This goal is to be achieved through filter retrofit and truck/engine replacement programs. This dissertation uses measurements of emissions from in-use HD diesel trucks at the Port of Oakland to evaluate the impacts of a DPF retrofit and truck replacement program. A plume capture method was developed to quantify black carbon (BC) and NOx emission factors for individual trucks and to characterize emission factor distributions. A comparison of emissions measured before and after the implementation of the truck retrofit/replacement rule shows a 54 " 11% reduction in the fleet-average BC emission factor, accompanied by a shift to a more highly skewed emission factor distribution. Although only particulate matter mass reductions were required in the first phase of the program, a 41 " 5% reduction in the fleet-average NOx emission factor was observed. These results provide an in-use/real-world assessment of the impact of DPF emission control systems, and a preview of emissions changes that may be expected from the extension of similar control programs to the entire HD truck fleet in California beginning in 2014. The plume capture method was further applied to measure emissions from a more diverse population of trucks observed at the Caldecott tunnel in summer 2010. Emissions from hundreds of individual trucks were measured, and emission factor distributions were characterized for nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), formaldehyde, BC, as well as optical properties of the emitted particles. Emission factor distributions for all species were skewed, with a small fraction of trucks contributing disproportionately to total emissions. For example, half of the total measured NO2 and BC were produced by only 10% of the total measurements. Total NOx and formaldehyde showed less skewed emission factor distributions compared to CO and BC. Emission factors for NO2 were found to be anti-correlated with all other pollutants considered here. Also, the fleet-average NO2 emission factor increased 34 " 18% relative to the corresponding value measured at the same location in 2006. These findings confirm that the use of catalyzed DPF systems is leading to increased primary NO2 emissions. Absorption and scattering cross-section emission factors were used to calculate the aerosol single scattering albedo (SSA, at 532 nm) for individual truck exhaust plumes, which averaged 0.14 " 0.03. This value of aerosol SSA is very low compared to typical values (0.90-0.99) observed in ambient air studies. It is indicative of a strongly light-absorbing aerosol, due to the high BC emissions that are a characteristic feature of diesel exhaust PM emissions. Measurements at the Caldecott tunnel also included efforts to quantify light-duty (LD) gasoline vehicle emission factors, and further investigation of the relative contributions of on-road gasoline and diesel engines to air pollutant emissions. Measurements of CO, NOx, PM2.5, BC, and organic aerosol (OA) were made in a tunnel traffic bore where LD vehicles account for>99% of total traffic. Measured pollutant concentrations were apportioned between LD gasoline vehicles and diesel trucks, and fleet-average emission factors were quantified for LD gasoline vehicles using a carbon balance method. Diesel trucks contributed 18 " 3, 22 " 5, 44 " 8% of measured NOx, OA, and BC concentrations, respectively, despite accounting for
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We have derived ambient black carbon (BC) concentrations and estimated emission factors for on-road diesel vehicles from archived Coefficient of Haze (COH) data that was routinely collected beginning in 1967 at 11 locations in the San Francisco Bay Area. COH values are a measure of the attenuation of light by particles collected on a white filter, and available data indicate they are proportional to BC concentrations measured using the conventional aethalometer. Monthly averaged BC concentrations are up to five times greater in winter than summer, and, consequently, so is the population's exposure to BC. The seasonal cycle in BC concentrations is similar for all Bay Area sites, most likely due to area-wide decreased pollutant dispersion during wintertime. A strong weekly cycle is also evident, with weekend concentrations significantly lower than weekday concentrations, consistent with decreased diesel traffic volume on weekends. The weekly cycle suggests that, in the Bay Area, diesel vehicle emissions are the dominant source of BC aerosol. Despite the continuous increase in diesel fuel consumption in California, annual Bay Area average BC concentrations decreased by a factor of (almost equal to)3 from the late 1960s to the early 2000s. Based on estimated annual BC concentrations, on-road diesel fuel consumption, and recent measurements of on-road diesel vehicle BC emissions, diesel BC emission factors decreased by an order of magnitude over the study period. Reductions in the BC emission factor reflect improved engine technology, emission controls and changes in diesel fuel composition. A new BC monitoring network is needed to continue tracking ambient BC trends because the network of COH monitors has recently been retired.
Author: Toshihiro Kuwayama
Author: Toshihiro Kuwayama
Author: Timothy Ryan Dallmann
Author: José Luis Jiménez-Palacios
Author: Dennis McClement
Author: California. Bureau of Air Sanitation
Author: Michael Arthur Robert
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Author: California. Bureau of Air Sanitation