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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.
1

Pollution characteristics of polyaromatic organic contaminants in PM₂.₅ from typical regions of China

Zhang, Yanhao 18 August 2020 (has links)
Air pollution has become a serious environmental issue around the world. Among the multiple pollutants like NOx and O3, the atmospheric particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) has been the most serious problem lately. The daily life and health of general public are greatly affected by PM2.5. For instance, the extended exposure to PM2.5 was reported to have association with increased prevalence of heart and lung diseases. China has suffered from serious PM2.5 pollution for many years. The vast territory, abundant anthropogenic activities and various geographical features make the formation mechanisms and possible health effects of PM2.5 become diverse and complicated. Because of that, regional study is necessary to control PM2.5 pollution and reduce the associated health risks. Taiyuan and Guangzhou are two typical megacities with strong regional characteristics in North and South China, both of which are subjected to PM2.5 pollution for long time. Through the analysis of PM2.5 samples collected from Taiyuan and Guangzhou, it will benefit the investigations of sources and toxicities of PM2.5 in Northern and Southern regions in China. Due to the complexity, research on components of PM2.5 is important. Polyaromatic organic contaminants are an important PM2.5 composition because of their relatively high concentration and obvious toxicity. In this study, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), hydroxy-PAHs (OHPAHs) in PM2.5 samples from Taiyuan and Guangzhou were determined. A novel atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS) method with higher sensitivity was developed. 19 PAHs, 18 NPAHs and 12 OHPAHs in PM2.5 were analyzed with the method detection limits of 0.021 (PAHs), 0.001 (NPAHs) and 0.005 (OHPAHs) pg m-3, respectively. The developed APGC-MS/MS method provided acceptable recoveries (70 - 120%) and precision (RSD < 15%). PM2.5 samples collected from Taiyuan and Guangzhou from May. 2017 to April. 2018 were analyzed for 19 PAHs, 18 NPAHs and 12 OHPAHs. The pollution characteristics, including contamination levels, sources and possible influences on human health, were investigated and compared between the two sampling sites. Compared to Guangzhou, Taiyuan had higher contamination levels for most of the determined PAHs, NPAHs and OHPAHs in PM2.5. Except for NPAHs, whose major source was the OH· radical-initiated secondary formation, the predominant pollution sources of PAHs and OHPAHs in PM2.5 were different in these two cities. The mixed primary source of coal combustion and traffic emission was predominant for both PAHs and OHPAHs in PM2.5 from Taiyuan. But in Guangzhou, single primary traffic emission was major source. Higher carcinogenic health risks of PM2.5 were found in Taiyuan for adults, children and infants compared to Guangzhou based on the determined concentrations of PAHs and NPAHs. Obvious temporal and spatial variations among Taiyuan and Guangzhou were seen, which indicated that the pollution status of PAHs, NPAHs and OHPAHs in PM2.5 in Taiyuan was serious. The pollution levels of PM2.5-bound PAHs and NPAHs in Guangzhou also became higher in recent years. Besides PAHs and their derivatives, 14 emerging polycyclic aromatic sulfur heterocycles (PASHs) were detected in PM2.5 collected from Taiyuan and Guangzhou. They were assessed by accurate quantification, investigation of contamination levels and pollution sources, and the preliminary studies of pollutant-induced toxic effects. A novel APGC-MS/MS method was developed for the determination of the PASHs in PM2.5 with superior sensitivity of 0.052 -1.673 pg m-3. Higher contamination levels in atmosphere were found in Taiyuan at ng m-3. Coal combustion/secondary formation and traffic emission/secondary formation were found as pollution sources of the PASHs in PM2.5 from Taiyuan and Guangzhou, respectively. Dithiothreitol (DTT) and cell viability assays were performed for the preliminary assessment of PASH-induced reactive oxygen species (ROS) production and cell toxicity based on the exposure dosage for human. The results indicated that PASHs in PM2.5 collected from Taiyuan could lead to oxidative stress and human bronchial epithelial cells' death. The toxicity results suggest that more efforts are necessary to control the local primary sources and secondary formation of PASHs in PM2.5. In summary, a novel analytical method using APGC-MS/MS was developed and successfully applied for determination of different polyaromatic organic contaminants in PM2.5. 19 PAHs, 18 NPAHs, 12 OHPAHs and 14 PASHs in PM2.5 collected from Taiyuan and Guangzhou, the typical regions in North and South China, were determined. The pollution characteristics, including contamination levels, sources, health risks and temporal/spatial distributions were investigated and compared. Significantly different pollution characteristics of PAHs, NPAHs and OHPAHs in PM2.5 showed a close connection between pollution features with local economic structures. For the 14 emerging PASHs, their pollution status, sources and implication for human health in these two sites were studied. Compared to Guangzhou, Taiyuan had relatively higher exposure levels and health risks of PASHs in PM2.5 for local people. The study of pollution characteristics of the polyaromatic organic contaminants in PM2.5 from representative areas could provide a useful guidance for PM2.5 pollution control and general public health protection in China.
2

Pollution characteristics of polyaromatic organic contaminants in PM₂.₅ from typical regions of China

Zhang, Yanhao 18 August 2020 (has links)
Air pollution has become a serious environmental issue around the world. Among the multiple pollutants like NOx and O3, the atmospheric particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) has been the most serious problem lately. The daily life and health of general public are greatly affected by PM2.5. For instance, the extended exposure to PM2.5 was reported to have association with increased prevalence of heart and lung diseases. China has suffered from serious PM2.5 pollution for many years. The vast territory, abundant anthropogenic activities and various geographical features make the formation mechanisms and possible health effects of PM2.5 become diverse and complicated. Because of that, regional study is necessary to control PM2.5 pollution and reduce the associated health risks. Taiyuan and Guangzhou are two typical megacities with strong regional characteristics in North and South China, both of which are subjected to PM2.5 pollution for long time. Through the analysis of PM2.5 samples collected from Taiyuan and Guangzhou, it will benefit the investigations of sources and toxicities of PM2.5 in Northern and Southern regions in China. Due to the complexity, research on components of PM2.5 is important. Polyaromatic organic contaminants are an important PM2.5 composition because of their relatively high concentration and obvious toxicity. In this study, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), hydroxy-PAHs (OHPAHs) in PM2.5 samples from Taiyuan and Guangzhou were determined. A novel atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS) method with higher sensitivity was developed. 19 PAHs, 18 NPAHs and 12 OHPAHs in PM2.5 were analyzed with the method detection limits of 0.021 (PAHs), 0.001 (NPAHs) and 0.005 (OHPAHs) pg m-3, respectively. The developed APGC-MS/MS method provided acceptable recoveries (70 - 120%) and precision (RSD < 15%). PM2.5 samples collected from Taiyuan and Guangzhou from May. 2017 to April. 2018 were analyzed for 19 PAHs, 18 NPAHs and 12 OHPAHs. The pollution characteristics, including contamination levels, sources and possible influences on human health, were investigated and compared between the two sampling sites. Compared to Guangzhou, Taiyuan had higher contamination levels for most of the determined PAHs, NPAHs and OHPAHs in PM2.5. Except for NPAHs, whose major source was the OH· radical-initiated secondary formation, the predominant pollution sources of PAHs and OHPAHs in PM2.5 were different in these two cities. The mixed primary source of coal combustion and traffic emission was predominant for both PAHs and OHPAHs in PM2.5 from Taiyuan. But in Guangzhou, single primary traffic emission was major source. Higher carcinogenic health risks of PM2.5 were found in Taiyuan for adults, children and infants compared to Guangzhou based on the determined concentrations of PAHs and NPAHs. Obvious temporal and spatial variations among Taiyuan and Guangzhou were seen, which indicated that the pollution status of PAHs, NPAHs and OHPAHs in PM2.5 in Taiyuan was serious. The pollution levels of PM2.5-bound PAHs and NPAHs in Guangzhou also became higher in recent years. Besides PAHs and their derivatives, 14 emerging polycyclic aromatic sulfur heterocycles (PASHs) were detected in PM2.5 collected from Taiyuan and Guangzhou. They were assessed by accurate quantification, investigation of contamination levels and pollution sources, and the preliminary studies of pollutant-induced toxic effects. A novel APGC-MS/MS method was developed for the determination of the PASHs in PM2.5 with superior sensitivity of 0.052 -1.673 pg m-3. Higher contamination levels in atmosphere were found in Taiyuan at ng m-3. Coal combustion/secondary formation and traffic emission/secondary formation were found as pollution sources of the PASHs in PM2.5 from Taiyuan and Guangzhou, respectively. Dithiothreitol (DTT) and cell viability assays were performed for the preliminary assessment of PASH-induced reactive oxygen species (ROS) production and cell toxicity based on the exposure dosage for human. The results indicated that PASHs in PM2.5 collected from Taiyuan could lead to oxidative stress and human bronchial epithelial cells' death. The toxicity results suggest that more efforts are necessary to control the local primary sources and secondary formation of PASHs in PM2.5. In summary, a novel analytical method using APGC-MS/MS was developed and successfully applied for determination of different polyaromatic organic contaminants in PM2.5. 19 PAHs, 18 NPAHs, 12 OHPAHs and 14 PASHs in PM2.5 collected from Taiyuan and Guangzhou, the typical regions in North and South China, were determined. The pollution characteristics, including contamination levels, sources, health risks and temporal/spatial distributions were investigated and compared. Significantly different pollution characteristics of PAHs, NPAHs and OHPAHs in PM2.5 showed a close connection between pollution features with local economic structures. For the 14 emerging PASHs, their pollution status, sources and implication for human health in these two sites were studied. Compared to Guangzhou, Taiyuan had relatively higher exposure levels and health risks of PASHs in PM2.5 for local people. The study of pollution characteristics of the polyaromatic organic contaminants in PM2.5 from representative areas could provide a useful guidance for PM2.5 pollution control and general public health protection in China.
3

The response of poplar clones to atmospheric pollution by ozone and sulphur dioxide

Kargiolaki, Hariklia January 1989 (has links)
No description available.
4

Toxicokinetics of inhaled trimethylbenzenes in man /

Järnberg, Jill, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Univ. / Härtill 6 uppsatser.
5

Airborne concentrations of formaldehyde in a pathology unit

Ntsuba, Hlosi Samuel 19 January 2012 (has links)
Background This descriptive cross-sectional study aimed to assess the exposure to formaldehyde associated with the tasks in a pathology laboratory unit. The study objectives were to describe the tasks involving the use of formaldehyde in the unit and assess exposure to formaldehyde as well as assess the effectiveness of existing engineering/ventilation system control methods. Methods The study involved observation and description of all tasks carried out in the laboratory, assessing exposure to formaldehyde and physical measurements of laboratory parameters such as area and volume. Exposure assessment involved three levels: task-based exposure assessment; personal exposure assessment and area exposure assessment. Formaldehyde measurements, by means of shadow sampling (personal breathing zone sampling by another person shadowing person being sampled) were taken using the formaldehyde meter. Data were summarised using means, medians and proportions and results were presented in figures and tables. For significance testing, an analysis of variance was carried out on the log-transformed data and p-value less than 0.05 were interpreted as statistically significant. Results Not all tasks in the laboratory were done according to the standard operating procedures. In general, exposure to formaldehyde was highest among the assistants group who were mostly responsible for high-exposure tasks. Mean STEL values for assistants, technologists and pathologist were 2.37ppm, 1.21ppm and 1.59ppm respectively, while for TWA, the figures were 0.60ppm, 0.36ppm and 0.21ppm. For short term exposures (STEL and peak values) pathologist exposure levels were higher than those of technologists while technologists were higher for long term exposures (daily exposure and 8-hour TWA). Daily exposure varied significantly for assistants and technologists but not for pathologist. Despite the use of engineering exposure controls for formaldehyde, 27/28 of all tasks were higher than the ACGIH threshold ceiling limit of 0.3ppm, 0.008ppm MRL value and 0.002ppm RELTWAConclusion The results have shown exposures among the employees of all job categories in this study, with laboratory assistants being the most exposed. Currently installed local ventilation system requires to be upgraded in accordance with best practices of 3.5m/s for air speed. Training, on PPE usage together with the medical surveillance should also be implemented. value.
6

Biological treatment of hazardous air pollutants from corn-to-biofuel dry mill production facilities

Chen, Li-Jung 02 June 2010 (has links)
Development of renewable energy sources such as ethanol has become a priority to meet growing energy demands. In the United States, the majority of ethanol is produced at dry mill facilities that convert corn to ethanol; these facilities can be a major emission source for volatile organic compounds (VOCs). Biofiltration is a promising VOC control technology but its effectiveness for the VOC mixtures emitted from ethanol production facilities has yet to be determined. The main goal of this research was to evaluate the feasibility of using biofiltration to treat ethanol plant air pollutants. To accomplish this, microbial degradation of four representative pollutants (formaldehyde, acetaldehyde, ethanol and acetic acid) was examined first in simplified batch reactors and then in a laboratory-scale biofilter system. The batch data indicate that, at a neutral pH, an enriched microbial consortium was capable of completely degrading formaldehyde, acetaldehyde and ethanol, and the Monod model was successfully utilized to describe single substrate degradation kinetics for these pollutants. However, the consortium only partially degraded acetic acid. In binary substrate experiments, acetaldehyde degradation was not significantly affected by either ethanol or formaldehyde. However, acetaldehyde inhibition of ethanol degradation was observed and inhibition kinetics were necessary to describe the observed ethanol removals. Formaldehyde degradation was inhibited in the presence of acetaldehyde and/or ethanol; however, further research will be required to identify the inhibtion. The biofilter study was performed to investigate the effects of pollutant loading, substrate mixtures and low pH on system performance. The results indicate that it is feasible to achieve greater than 97% overall removal efficiency at a short contact time of 5 seconds under neutral pH conditions. The level of substrate inhibition observed in the batch experiments was not evident in the biofilter experiments. However, low pH conditions gradually decreased the biofilter performance with a more significant impact on acetaldehyde, a result that was supported by batch data. Finally, a numerical model that integrated degradation kinetics was able to describe the biofilter performance under the test conditions. This research demonstrates that biofiltration has the potential to be a viable VOC treatment technology at corn-derived ethanol production facilities. / text
7

Chemical exposures, biological monitoring and cancer risks in Swedish aluminium foundries and remelting plants /

Westberg, Håkan, January 2001 (has links) (PDF)
Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 6 uppsatser.
8

Ethers as gasoline additives : toxicokinetics and acute effects in humans /

Nihlén, Annsofi, January 1900 (has links) (PDF)
Diss. (sammanfattning) Stockholm : Karol. inst., 1999. / Härtill 7 uppsatser.
9

Ozone and diesel exhaust : airway signaling, inflammation and pollutant interactions /

Bosson, Jenny, January 2007 (has links)
Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.
10

Air sanitation the nature and control of air contaminants, including dusts, fumes and smokes; mists and fogs; vapors, gases and odors; pollen, spores and bacteria : a preliminary report on a study of the scope of air sanitation and of contemporary problems in the control of air quality : submitted in partial fulfillment ... Master of Science in Public Health Engineering ... /

Witheridge, William N. January 1946 (has links)
Thesis (M.S.P.H.)--University of Michigan, 1946.

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