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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

Tempospatial distribution of platycephalids and the biology of Suggrundus macracanthus in the waters off southwestern Taiwan

Huang, Chien-Chih 11 September 2007 (has links)
This study aims to describe the spatial and temporal distribution of Platycephalids and the biology of the dominant species Suggrundus macracanthus, in the coastal waters off southwestern Taiwan. A beam trawl was adopted to collect fish samples from 7 stations, including Jiading, Zouying, Jhongjhou, Linyuan, Dapeng Bay, Linbian and Fangliao. Samplings were carried out on a 1-2 month interval, started from June 2000 and ended in August 2005. In total, 3,780 specimens were collected, including 9 genus 11 species. The distribution of Platycephalids varied in station, water depth and season. The lowest abundance were recorded at Jiading, then decreased from Zouying to Linyuan, and then increased southwards. Platycephalids eived more abundant in depth 25-55 m, and the number increased with depth 15-35 m. The highest abundance occurred from spring to summer. S. macracanthus (74%) were the top dominant species. S. macracanthus spawn once a year during February to April, with a peak in the frequency distribution of egg diameter. The recruitment of S. macracanthus occurred in the period from June to July, at near-shore waters of 15 m depth with mud and sand substrata. S. macracanthus take epibenthic shrimp as the major diet accounts for above 68%, including 59% of Metapenaeopsis palmensis. Other food items still had the fish, crab, Mollusca and Amphipoda. S. macracanthus juveniles nearly didn¡¦t ate crab, but the adult ate crab up to 12%.
2

Physicochemical Characteristics and Source Apportionment of Atmospheric Particles in Kinmen-Xiamen Region

Li, Tsung-chang 22 July 2009 (has links)
In recent years, the air quality of Kinmen-Xiamen region has deteriorated gradually, and PM10 was always the worst air quality indicator. Particularly, high PM10 concentration has been observed in spring and winter. The objective of this study was to characterize the chemical properties of atmospheric aerosol particles sampled at Xiamen Bay located at the west coast of Taiwan Strait by sampling atmospheric particles and using chemical mass balance (CMB) receptor model for source apportionment, which indicated the difference of background and episode periods. Furthermore, this study applied HYSPLIT model to figure out the transportation routes of polluted air mass by backward trajectory. Seven particulate matter (PM) sampling sites at Xiamen Bay, three sites at Kinmen Island and four sites at metro Xiamen, were selected for this particular study. Particulate matter sampling included regular and intensive sampling. Intensive sampling was conducted to collect PM2.5 and PM2.5-10 with dichotomous samplers in the spring and winter of 2008 and 2009, while regular sampling was conducted to collect PM10 with high-volume samplers twice a month since March 2008. Results from PM sampling indicated that atmospheric particles had a tendency to accumulate in Xiamen Bay all year round, particularly in spring and winter. Five sampling sites inside the Xiamen Bay had relatively higher PM concentration than two sampling sites outside the Xiamen Bay. It suggested that local emission at the Xiamen Bay was superior to long-range transportation from the Northeastern Monson. A superimposition phenomenon was regularly observed during the episodes at Xiamen Bay. The most abundant water-soluble ionic species of PM were SO42-, NO3-, and NH4+ at Xiamen Bay, the major chemical species of PM were secondary aerosols (i.e. (NH4)2SO4 and NH4NO3). Crustal elements (e.g. Ca, Mg, Fe, and Al) and anthropogenic elements (e.g. Zn and Pb) dominated the chemical species of particles. Backward trajectory results indicated that polluted air mass originated from Asian continent moved directly to Kinmen-Xiamen region in winter and spring, while air mass originated from the southwestern and southeastern ocean did not pass polluted region in summer, which result in better air quality of Kinmen-Xiamen region in summer than those in winter and spring. Results from CMB receptor modeling showed that the major sources of atmospheric PM10 at Kinmen-Xiamen region were soil dust, secondary aerosol, petroleum industry, motor vehicle exhanst, iron and steel industry, cement industry, Diesel vehicle exhanst marine aersols, and vegetative burning. The stationary sources were the major contributor accounting for approximately 50% of PM10 in Kinmen. It suggested that atmospheric particles were mainly originated from cross-boundary transport rather than local emission sources since there are no such kinds of industrial factories in Kinmen.
3

Influences of Sea-land Breezes and Northeastern Monsoon on the Transportation and Dispersion of Air Pollutants over Coastal Region in Southern Taiwan

Tsai, Hsieh-Hung 11 August 2010 (has links)
This study investigated the influences of sea-land breezes (SLBs) and northeastern monsoon (NEM) on the transportation and dispersion of air pollutants over coastal region in southern Taiwan. The physicochemical properties of particulate matter (PM) was simultaneously sampled and analyzed at both inland and offshore sites during eight intensive sampling periods. This study further used a SURFER 2-D plotting software, a backward trajectory model, a 3-D meteorological model (MM5), and a comprehensive air quality model (CAMx) to simulate surface wind fields and spatial distribution of air pollutants over the coastal region during the intensive sampling periods of SLBs and NEM. According to the meteorological condition and the synoptic weather patterns of the observation data showed that the SLBs sampling periods commonly occurred the weather patterns were zone of low pressure, pacific high pressure, and west stretch of the pacific high pressure when the main prevailing wind direction were west wind and southwest wind. During the NEM sampling periods, the weather patterns were strong northeastern monsoon, standard northeastern monsoon, and outflow rebound with high pressure in southern Taiwan, and then the main prevailing wind direction were northwest wind and northeast wind. However, during the MIX sampling periods, the weather patterns were outflow circulation of typhoon, weak northeastern monsoon, and outflow rebound with high pressure, while the wind directions didn¡¦t change regular. Thus, at coastal sites, the sea-land breezes induce an inland transport of air pollutants during the daytime and a seaward return of air pollutants at nighttime, causing a recirculation of air pollutants back to inland regions each day during the SLBs sampling periods. During the NEM sampling period was mainly brought from the northeastern wind which transported air pollutants from the northern region to Kaohsiung metropolitan area. The results of PM concentration and size distribution indicated that the inland sites had a higher fraction of fine particles (PM2.5), whereas the offshore sites had a higher fraction of coarse particles (PM2.5-10). These phenomena were attributed to the fact that marine aerosols are generally abundant in the coarse particles. PM concentration is relatively higher during the NEM sampling periods than during the SLBs and MIX sampling periods. For PM concentration, the order of secondary inorganic aerosols (SIA) was NEM > MIX > SLBs, while the SIA/Ions ratio of PM2.5 were approximately 50% during sampling periods. The [NO3-]/[SO42-] ratios of PM2.5 and PM2.5-10 during the SLBs sampling periods were always lowest than those during the NEM and MIX sampling periods. It is suggested that the PM concentrations during the SLBs sampling periods were highly influenced by stationary sources emissions. The crustal elements indicated that the Al, Ca, Fe, and K contributed major composition of particles. Artificial metals, such as Mg, Pb, V, and Zn were also enriched in the atmospheric PM during the NEM sampling periods. In addition, the higher concentration of Fe was attributed to local anthropogenic emission and weak northeastern monsoon during the MIX sampling periods. Regardless of inland or offshore sites, a high concentration of secondary organic carbon (SOC) during the NEM and MIX sampling periods was consistent with OC/EC ratio higher than 2.2 indicates the potential formation of secondary aerosols. Chloride deficit of PM at inland sites were lost easily for approximately 40.28% during the NEM sampling periods. Moreover, the lowest [Cl-]/[Na+] ratio occurred during the sampling periods when the chloride deficit was relative high at inland sites. According to the results of neutralization ratio (NR), regardless of the periods (SLBs, NEM, and MIX), the particulates of inland and offshore sites were both acid. During the NEM and MIX sampling periods, sulphur oxidation ratio (SOR) of PM2.5 over coastal region in southern Taiwan were above 0.25. It is suggested that the results of SOR during those sampling periods were highly influenced by long transportation. In addition, the nitrogen oxidation ratio was lower influenced than SOR over coastal region in southern Taiwan. It is suggested that air quality of Kaohsiung metropolitan area were influenced by the industrial source emissions. During the SLBs sampling period, sea breezes blown in the morning transported the offshore PM10 back to the inland sites in the Kaohsiung metropolitan area. In contrast, the air mass observed during the NEM sampling period was brought to the Kaohsiung metropolitan area mainly by a northerly wind which transported air mass originating in the northern region (i.e. Chiayi counties). The backward trajectory modeling of the MIX sampling periods suggested that the winds were dominated by the Northeastern Monsoon, and as such, likely inhibited the influences of sea-land breezes. Local surface air mass circulation over southern Taiwan obtained from MM5 model influenced by the southwestern monsoon during the SLBs sampling period. The weather in southern Taiwan during the NEM intensive sampling period was occasionally influenced by the Northeastern Monsoon as well as by complex terrain. During the MIX sampling periods, air mass recirculation was frequently observed in the coastal region of southern Taiwan. The results of CAMx model showed that air pollutions were occurred apparent sea breezes in the afternoon and land breezes at night during the SLBs sampling period. During the NEM sampling period, a strong Northeastern Monsoon blew air pollutions from the north to the southern region. We have compared the model simulation with field measured O3 and PM10 concentrations for inland and offshore regions. The order of correlation coefficients of ¬the model simulation and the measurement for O3¬ and PM10 in sampling periods is SLBs>MIX>NEM and NEM>MIX>SLBs, respectively. Overall, the correlation coefficients of the model simulation and the measurement were middle and high correlation.

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