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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Measurement and analysis of ambient atmospheric particulate matter in urban and remote environments

Hagler, Gayle S. W. 09 May 2007 (has links)
Atmospheric particulate matter pollution is a challenging environmental concern in both urban and remote locations worldwide. It is intrinsically difficult to control, given numerous anthropogenic and natural sources (e.g. fossil fuel combustion, biomass burning, dust, and seaspray) and atmospheric transport up to thousands of kilometers after production. In urban regions, fine particulate matter (particles with diameters under 2.5 m) is of special concern for its ability to penetrate the human respiratory system and threaten cardiopulmonary health. A second major impact area is climate, with particulate matter altering Earth s radiative balance through scattering and absorbing solar radiation, modifying cloud properties, and reducing surface reflectivity after deposition in snow-covered regions. While atmospheric particulate matter has been generally well-characterized in populated areas of developed countries, particulate pollution in developing nations and remote regions is relatively unexplored. This thesis characterizes atmospheric particulate matter in locations that represent the extreme ends of the spectrum in terms of air pollution the rapidly-developing and heavily populated Pearl River Delta Region of China, the pristine and climate-sensitive Greenland Ice Sheet, and a remote site in the Colorado Rocky Mountains. In China, fine particles were studied through a year-long field campaign at seven sites surrounding the Pearl River Delta. Fine particulate matter was analyzed for chemical composition, regional variation, and meteorological impacts. On the Greenland Ice Sheet and in the Colorado Rocky Mountains, the carbonaceous fraction (organic and elemental carbon) of particulate matter was studied in the atmosphere and snow pack. Analyses included quantifying particulate chemical and optical properties, assessing atmospheric transport, and evaluating post-depositional processing of carbonaceous species in snow.
262

Distribution and sources of polycyclic aromatic hydrocarbons(PAHs) in Er-Jen River

Lin, Chien-ming 22 July 2011 (has links)
In this study our purposes were to investigate the spatial distribution and seasonal variation of polycyclic aromatic hydrocarbons (PAHs) in the dissolved and particulate phase of PAHs in Er-Jen River. In addition, the potential sources of PAHs in Er-Jen River were investigated not only by finger printing, but also principal component analysis (PCA) and hierarchical cluster analysis (HCA). ¡@¡@Concentrations of dissolved and particulate PAHs ranged from 13.8 to 516 ng/L and from 4.05 to 55.9 ng/L, respectively. In March (dry season), concentrations of dissolved and particulate PAHs ranged from 38.3 to 186 ng/L and from 4.05 to 25.9 ng/L, respectively. In addition, concentrations of dissolved and particulate PAHs ranged from 32.3 to 82.8 ng/L and from 14.8 to 85.3 ng/L, respectively in September (wet season). The highest total PAH concentration in this area was found in Station Er-3 which is located on a tributary of Er-Jen River. Total PAH concentrations in wet season were higher than those found in dry season for all stations in Er-Jen River, except for station Er-3, which suggesting that different geography might be the reason. ¡@¡@Results from correlation analysis indicated that distributions of PAH concentrations for particulate phase in Er-Jen River correlated well with flow rate, suspended solid concentrations and salinity. Total PAH concentration of station Er-2, which was located at the downstream Er-Jen River, was highly correlated with salinity; while total PAH concentrations in other stations were mainly affected by flow rate, suspended solid concentrations and some potential sources of pollution. Results from PCA, HCA and finger printing all indicated the origins of PAHs were complex sources in the study area, including pyrogenic, petrogenic and diagenetic/biogenic origins. The origins of PAHs in dissolved phase were mainly from both pyrogenic and petrogenic sources; while those in particulate phase were mainly from pyrogenic sources. In addition, the pyrogenic origins in both dissolved and particulate phase were mostly from liquid fuel combustion. In wet season, howerer, diagenetic/biogenic origins were also found in particulate phase at the sampling sites of Er-Jen River. ¡@¡@The annual total PAH fluxes of Er-Jen River were estimated to be 23.1 kg For dissolved phase, the average daily fluxes in dry and wet season were 5.9 g/day and 65.8 g/day, respectively, with an annual mean fluxe of 11.3 kg/year. For particulate phase, the mean daily fluxes in dry and wet season were 0.8 g/day and 76.2 g/day, respectively, with an annual mean flux of 11.8 kg/year. In general, the total PAH fluxes in wet season were higher than dry season. The total annual PAH fluxes in Er-Jen River were generally less than those reported worldwide, and comparable to those in San Francisco River in USA, but higher than those in Le Havre River in France.
263

Physicochemical Characteristics and Source Apportionment of Ambient Suspended Particles at Boundary and Sensitive Sites Surrounding a Steel Manufacturing Plant

Liao, Chia-cheng 24 August 2012 (has links)
Steel industry is a highly polluted industry and one of the most important stationary sources in Kaohsiung City. The steel manufacturing process could emit a huge amount of particles, such as the sintering process, the blast furnace operation, and the raw material handling process. Suspended particles emitted from steel industry could deteriorate ambient air quality and cause adverse effects on human health. In order to understand the impact of steel industry on ambient air quality in Siaogang District and to identify potential pollution sources, this study selected a integrated steel manufacturing plant located at Siaogang District to conduct a sampling protocol of suspended particulate matter (PM) at ambient sites (A1~A5) and sensitive sites (S1~S5) from July 2011 to March 2012. The size distribution of suspended particles in four seasons was measured with PM10 high-volume samplers, dichotomous samplers, and MOUDI for 3 days (24 hours for single sampling), and dustfall samplers for one month, to investigate the spatial distribution and temporal variation of PM concentration. After sampling, the physicochemical properties of PM, including mass concentration, particle size distribution, dustfall concentration, water-soluble ionic species, metallic elements, and carbonaceous contents, were further analyzed. Field measurement of ambient PM showed that the averaged ambient PM10 concentration (53.54 - 203.56 £gg/m3) were higher than sensitive sites (55.06 - 140.07 £gg/m3) and the averaged ambient PM2.5 concentration of ambient (23.10 - 120.21£gg/m3) were higher than sensitive sites (12.52 - 65.62 £gg/m3). No matter ambient or sensitive sites, it showed a tendency of lower concentration in summer, indicating that concentration variation of PM10 and PM2.5 were highly affected by meteorological factors (such as wind direction, wind speed, and relative humidity) in Siaogang District. Furthermore, a t-test result showed that ambient and sensitive sites have similar pollution sources since the p-values were in significantly different. Chemical analysis of PM results showed that the most abundant water-soluble ionic species of PM at the ambient and sensitive sites were secondary inorganic aerosols (SO42-, NO3-, and NH4+) and [NO3-]/[SO42-] showed that ionic species were mainly emitted from stationary sources. Fe, Al, K and Ca were the major metallic elements of this study, and the major pollution sources contain industries, traffics, and road dusts. Additionally, the raw material handling process was the major pollution source of PM. Correlation analysis of OC and EC showed that PM at ambient and sensitive sites were originated from primary sources, such as vehicles, industries, road dusts, and human activities. Results obtained from PCA and CMB receptor modeling showed that both PM2.5 and PM10 highly correlated with wind direction in different season and the major pollution sources were industry pollution (including petroleum refineries, power plants, waste incinerators, consistent operating steel mills and electric arc furnace steel mills, etc.), followed by local traffics and derivative. Furthermore, marine aerosols were one of the important pollution sources at sensitive sites (S1, S4, and S5) where close to the ocean.
264

Burial and decomposition of particulate organic matter in a temperate, siliciclastic, seasonal wetland

Welsh, Lisa Williamson 15 May 2009 (has links)
Understanding the role of freshwater wetlands in the global carbon cycle has become more important as evidence of climate change grows. In this paper, we examine the burial and decomposition of particulate organic matter (POM) in a temperate, siliciclastic, seasonal wetland. High POM abundances are found in silt layers, while sand units preserve very little POM. The POM distribution with depth is compared to the biogeochemistry of sediment porewater with depth. POM acts as a driver for reduction reactions within the wetland soil. Porewater biogeochemistry and POM decomposition are controlled by seasonal changes in the level of the water table which cause seasonal shifts in the oxic/anoxic boundary. At the oxic/anoxic boundary, reoxidation of FeS minerals in the soil cause rapid POM decomposition at the average minimum water table level in the late summer and early fall. Variation in the minimum depth of the water table from year to year may account for fluctuating POM numbers in the upper silt layers. The results from this study can be used to predict seasonal water level fluctuations in ancient wetland and to explain recurrence horizons in peat.
265

Evaluation of PM10 and Total Suspended Particulate Sampler Performance Through Wind Tunnel Testing

Thelen, Mary Katherine 2010 August 1900 (has links)
Particulate matter (PM) concentrations in ambient air can be monitored by gravimetric sampling near a source using Federal Reference Method (FRM) samplers. PM is regulated by size, with PM10, which is comprised of particles with aerodynamic equivalent diameters less than or equal to 10 μm, being the main focus of this research. FRM PM10 samplers exhibit sampling errors when sampling dusts with mass median diameters (MMDs) that are larger than the 10 μm sampler cutpoint. For industries to be regulated equitably, these sampler errors must be quantified and understood. This research evaluates the performance of FRM PM10 and low volume total suspended particulate (TSP) samplers under the controlled conditions of a wind tunnel. The performance evaluation was conducted by observing the sampler cutpoints, slopes, and measured concentrations. These measured values were compared to values obtained using a collocated isokinetic reference sampler. The results of this research indicate that PM10 samplers do not operate as intended under all conditions. The cutpoint of the PM10 inlets was significantly higher than the maximum FRM limit of 10.5 μm when sampling dust with MMDs larger than the cutpoint of the sampler. The slope values for the PM10 inlets were significantly higher than the maximum FRM limit of 1.6. MMDs and geometric standard deviations of PM collected by TSP samplers were significantly different than those of PM collected using the collocated isokinetic sampler. The concentrations measured by the TSP samplers were significantly higher than the collocated isokinetic sampler. The results of this research provide a better understanding of the performance of TSP and PM10 samplers operating under different conditions and shows that these samplers are not operating as intended. Because of this, industries may be suffering the consequences of inequitable regulation.
266

Physicochemical Properties and Exposure Assessment of Suspended Particles in Steel Plants

Her, Chia-Ta 24 August 2004 (has links)
The objective of this study was to investigate the exposure assessment and health risk of particulate matter emitted from steel industry for high-risk inhabitants living in metro Kaohsiung. A steel plant and an electric arc plant were selected for conducting the sampling of particulate matter (PM). The physical and chemical properties of PM sampled at the working place and at the fence of selected plants were also analyzed to establish the fingerprints of PM in the steel industry. In order to accomplish this study, both personal sampling and environmental sampling were conducted in steel plants. Personal exposure sampling was undertaken at working places, while the conduction of environmental sampling might affected by various uncertain environmental factors (such as meteorological condition and other emission sources), but it could characterize the overall environmental situation and help exposure assessment. Moreover, The exposure of employers (including manufacturing workers and supporting staffs) could be further assessed based on the concentration and duration of PM exposure. Specific metal concentration was obtained from working environment, searching for exposure parameter (such as exposure frequency, exposure duration, body weight, average time, and etc.) and toxicity database (e.g. cancer slope factor and reference dose). The data could be used for assessing both cancer risk and non-cancer risk of specific heavy metal. Sampling data obtained from working places showed that the highest PM concentration were observed during the electric arc process, especially the charging and discharging procedures. The concentration of PM1.0, PM10, and TSP at the working places were 53.3~195.6 £gg/m3 ,365.7~550.0 £gg/m3, and 1085.5~2755.0 £gg/m3, respectively. Measured at the outdoor environments of working places, the highest PM10 and TSP concentration, ranging from 365.7~550.0 £gg/m3 and 1085.5 ~2755.0 £gg/m3, were observed at the sinter plants of a steel manufacturer. Sampling data obtained at the fence of steel plants (a steel plant and electric arc plant) indicated that the concentration of PM10 and TSP exceeded the ambient air quality standards. Modification of manufacturing process and improvement of PM collection system are highly required to reduce the concentration level as well as the emission of PM. Results of fingerprint of PM (PM2.5, PM2.5-10, TSP) obtained from working places showed that iron, calcium, sulfate, nitrate, calcium ion, and elemental carbon were the major chemical content of PM at the melting plant, the sinter plant, and the storage field. While, iron, calcium, sulfate, nitrate, calcium ion, and organic carbon were the major chemical content of PM at electric arc plant. Results of personal exposure concentration and exposure dose of PM showed that the highest exposure level of both manufacturing workers and supporting staffs were observed at the storage field, while the lowest exposure level was found at the sinter plant. Therefore, enforcement of wearing maskers and/or shelters at the storage field is also highly recommended to prevent manufacturing workers from the exposure of high-level PM at working places. Moreover, the cancer risk of manufacturing workers exposured to hexavalent chromium (Cr6+) at the melting plant, the sinter plant, the storage field, and the electric arc plant exceeded acceptable cancer risk standard (10-5~10-6), while the hazard index of manganese (Mn) was much higher than other metals.Meanwhile, exposuring to Cr6+, Ni, and Mn at the electric arc plant also exceeded acceptable standards (Cr6+ and Ni¡G10-5~10-6 , Mn¡G1). Several control strategies, including pollution reduction measures such as the usage of clean fuel, process modification, the improvement of collection system, the enhancement of manufacture management, the conduction of environmental monitoring and exposure assessment, floor cleanup and truck entrance management, are recommended to improve the contamination of PM at working places and surrounding environments for metallurgic industries. Moreover, enforcement of wearing maskers and/or shelters at high-risk environments is also highly recommended to prevent manufacturing workers from the exposure of high-level PM at working places. Keywords: steel industry, particulate matter sampling, physical and chemical characteristics, exposure assessment, health risk
267

Investigation Of The Effect Of Oxidation Filters On The Particulate Emissions Of Diesel Engines

Cerit, Ersen Recep 01 September 2006 (has links) (PDF)
Oxidation filters are used to decrease particulate emissions commonly. In this study, design of a particulate trap to produce an alternative, low cost filter has been aimed. An experimental setup has been installed according to standards to carry out tests of these designed filters. Electronic measurement and control systems have been attached to this setup to increase efficiency of experiments. Two filter designs have been used in the experiments. First design consists of aluminum wire cloth. Second design is sheet metal structure, which includes three longitudinal cells. Metal chip is used as filter material. Empty filter tests have been performed firstly, and then experiments have been repeated with aluminum, iron, and copper chip addition in filter. Copper chip test results are better than other metal chip for first experiments. Afterwards, experiments have been repeated with varying copper chip amount. Suitable copper chip amount was determined based on fuel consumption rate of the engine. As a result, designed filter reduce the particulate emissions with high efficiency. Although, carbon monoxide, and carbon dioxide gaseous emissions increase with designed filter, hydro carbon emissions decrease.
268

Time-Series Sediment Traps Mooring in South Okinawa Trough: Particulate Fluxes and Pb-210 Study

Chung, Kendy 08 June 2000 (has links)
Abstract The research was conducted as a part of the phase III of the KEEP(Kuroshio Edge Exchange Processes)program. Two strings of sediment traps were deployed simultaneously: one near the outlet of North Mien-Hua Canyon (T15), and the other at the south rim of the South Okinawa Trough (T16). The purposes are to collect settling particulates at various depths for the studies of temporal and spatial variations of the particulate flux, 210Pb activity, 210Pb flux and size distribution. The particulate fluxes showed synchronous variations among the traps deployed at different depths of the same site. In general, the particulate flux in the marginal sea areas increases with depth but the maximum values may be at the mid-depth rather than at the deepest trap and remain so for the entire mooring period as observed at T15 and T16. Unusually high particulate fluxes could occur within the same period, probably reflecting an episodic event, such as typhoon or rain storm. 210Pb activity measured from different depths at T15 and T16 increases generally with depth along with the increase of the particulate flux toward the bottom. The temporal variation of 210Pb activity is generally smaller than that of the particulate flux in terms of relative amplitude. At the outlet of the canyon, T15, the temporal mean particulate flux of each trap ranged from 0.16 to 3.3 g/m2/d(a factor of ~ 20), while the mean 210Pb activity of each trap varied from about 98 to 168 dpm/g. At T16 located at the south rim of the South Okinawa Trough, the temporal mean particulate flux ranged from 0.06 to 5.7 g/m2/d(a factor of ~ 100), while the mean 210Pb activity varied from 82 to 192 dpm/g. The particulate 210Pb flux was smaller at T15 than at T16 because T15 has smaller particulate flux. The trapped particulates in the canyon(T1-T3) are mostly silt and sand, while the particulates collected from the Okinawa Trough(T15, T16) are mainly silt and clay. The 210Pb activity of the former is much lower than that of the latter, indicating the enrichment of 210Pb on the fine particulates. As the fine-grained particulates away from landmass have longer residence time in the ambient water, they can scavenge 210Pb more effectively.
269

Pb-210 and Po-210 in the Western South Okinawa Trough:Distribution Pattern and Radioactive Disequilibrium

Chu, Kevin 19 July 2001 (has links)
In this study, the settling particulates collected by time-series sediment traps, sediment cores, and seawater samples taken in the western South Okinawa Trough were analyzed for 210Pb and 210Po in order to understand the characteristics of the particulates and sediments based on the distribution of these two nuclides and the extent of their radioactive disequilibrium. Two sediment traps were deployed at T18 (24¢X45'N 122¢X18'E, about 300m and 100m above bottom) from February to August 1999. The results show that higher mass fluxes were observed from February to April, ranging between 16 and 56 g/m2/d. The 210Pb activity increases systematically with time from about 80 to 100 dpm/g, and the upper trap has slightly higher values. Similar to 210Pb, the 210Po activity also increases, but from near zero to only 27 dpm/g for both traps, much lower than the corresponding 210Pb activity. The 210Pb activities are quite different between the settling particulates collected by traps at T18 and the surface sediment taken nearby (the former have a mean activity of about 85 to 90 dpm/g; the latter has a value of only 11 dpm/g). The size distribution and elemental composition are also different between the trapped particulates and the sediment. Thus the underlying sediments were not directly derived from the overlying trapped particulates. Except for T4 core below 15cm and T19 entire core, the 210Po/210Pb activity ratio in the sediments varies greatly, from near zero to 0.7, indicating deficiency of 210Po. Both 210Po and 210Pb activities are much lower in the sediments than in the settling particulates. A T19 both 210Po and 210Pb activities in the core decrease steeply from 120 dpm/g at surface to 60 dpm/g at 4 cm, indicating radioactive equilibrium. This is entirely different from the cores taken at other stations. The total 210Po/210Pb activity ratio in the water column at T17 is nearly constant at about 0.6, but drops to 0.3 below 700m, i.e. 210Po activity is deficient in the entire water column. At T18, the activity ratio is about 1.3 between 100m and 300m, indicating a 210Po excess in this layer. Below 400m, the ratio is about 0.6 to 0.7, showing 210Po deficit again. These observations indicate that the water columns at T17 and T18 are stratified, probably due to lateral transport. Based on the 210Po/210Pb activity ratio the mean residence time of 210Po with respect to particulate scavenging ranges from 3 to 16 months.
270

Engineering analysis of fugitive particulate matter emissions from cattle feedyards

Hamm, Lee Bradford 12 April 2006 (has links)
An engineering analysis of the fugitive particulate matter emissions from a feedyard is not simple. The presence of an evening dust peak in concentration measurements downwind of a feedyard complicates the calculation of an average 24-h emission flux for the feedyard. The evening dust peak is a recurring event that occurs during evening hours when particulate matter concentration measurements increase and decrease dramatically during a short period of time. The concentrations measured during the evening can be up to 8 times the concentrations measured throughout the rest of the day. There is a perception that these concentration increases are due to increases in cattle activity as the temperature decreases during the evening. The purpose of Objective 1 of this research was to quantify the changes in concentrations based on changes in meteorological conditions and/or cattle activity. Using ISCST3, a Gaussian-based EPAapproved dispersion model used to predict concentrations downwind of the feedyard , the results of this work indicate that up to 80% of the increase in concentrations can be attributed to changes in meteorological conditions (wind speed, stability class, and mixing height.)The total fugitive particulate matter emissions on a cattle feedyard are due to two sources: unpaved roads (vehicle traffic) and pen surfaces (cattle activity). Objective 2 of this research was to quantify the mass fraction of the concentration measurements that was due to unpaved road emissions (vehicle traffic). A recent finding by Wanjura et al. (2004) reported that as much as 80% of the concentrations measured after a rain event were due to unpaved road emissions. An engineering analysis of the potential of the unpaved road emissions versus the total feedyard emissions using ISCST3 suggests that it is possible for 70 to 80% of the concentration measurements to be attributed to unpaved road emissions. The purpose of Objective 3 was to demonstrate the science used by ISCST3 to predict concentrations downwind of an area source. Results from this study indicate that the ISCST3 model utilizes a form of the Gaussian line source algorithm to predict concentrations downwind of an area source.

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