| Summary: | 碩士 === 國立成功大學 === 環境工程學系碩博士班 === 101 === This study investigates the characteristics of polychlorinated dibenzo -p-dioxins and dibenzofurans (PCDD/Fs) in the atmosphere and soils of northern Taiwan. The ambient air and soils were collected seasonally in the vicinity of three municipal solids waste incinerators to determine the concentration of PCDD/Fs. Gaseous and particle concentrations were both obtained by measurement and simulation, and dry and wet deposition fluxes and scavenging ration were also developed. The PCDD/F congener profiles of soils show that 1,2,3,4,6,7,8-HpCDD (3.57%) , OCDD (89.1%) and OCDF (3.35%) were dominant among seventeen congeners and OCDD (89.1%) shows significant high fraction. Comparing the fraction of OCDD in the soils to that in the ambient air, OCDD also show higher value in the soils than in the atmosphere. This result refer that OCDD is more resistant in the environment than other congeners. In the study of dry and wet deposition, we could find that both rainfall and rainy days would determine which process – dry or wet deposition – is more important during the atmospheric deposition. Moreover, the temperature changes during the seasons, the difference in chlorine atoms of each congener and particle characteristics would also have impact to the gas and particle partitioning. Additionally, the artifacts during sampling work due to the adsorption and blow-off mechanism were supposed to be neglected. Due to the different toxicity of each congener, this study used the view of toxicity to find out the influences of PCDD/Fs in northern Taiwan. From this study, the annual PCDD/F-I-TEQ wet deposition in Taipei city ranged from 399-775 (pg I-TEQ/m2-year) during 2006 to 2011. Since wet precipitation is more valid in scavenging particulate PCDD/Fs, the fluxes of dioxins in rainy season are higher than those in dry seasons. Therefore, the distribution of rainy season in each year have significant impacts on annual wet deposition flux. And regard to the annual PCDD/F-I-TEQ total deposition (dry+wet) in Taipei city ranged from 1.18-4.94 (ng I-TEQ/m2-year) during 2006 to 2011. Wet deposition account for 13.6-42.4 % among annual total PCDD/F-I-TEQ deposition (dry+wet), revealing that the part of dry deposition shows Factors that might affect the PCDD/F-I-TEQ deposition fluxes were seasonal changes, formation of inversion layers, domestic heating, photolysis and chemical reactions. In comparison with previous studies, the data gain in this study showed the characteristics of PCDD/F in Taipei city and can provide reference to governors and further studies.
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