| As a typical representative of persistent organic pollutants, PCDD/Fs are of widely concerned due to their persistence, transportation, bioaccumulation and toxicity to biota. Consequently, investigation on level and emission sources of these pollutants as well as establishment of effective prevention measurement and legislation are hot global topics. In this thesis, atmospheric PCDD/Fs of Guangzhou, a typical southern city, was studied for environmental action (temporal and spatial distribution, sources, transportation and transformation). In addition, human risks of PCDD/Fs via inhalation were assessed. Moreover, some PCDD/Fs emission sources impacting on Guangzhou atmospheric quality were investigated preliminarily.The levels of atmospheric PCDD/Fs in Guangzhou were associated with regional environment. The mean concentrations (I-TEQ values) for Huadu district, Liwan district, Tianhe district and Huangpu district were 3815 fg/m~3 (104.6 fg I-TEQ/m~3), 12777 fg/m~3 (430.5 fg I-TEQ/m~3), 6963 fg/m~3 (163.7 fg I-TEQ/m~3) and 10953 fg/m~3 (769.3 fg I-TEQ/m~3), respectively. The concentration distribution trend is suburb < residential area < industrial area. Liwan district and Huangpu district are seriously polluted areas due to industrial activities. On the other hand, after annual monitoring of atmosphere at Tianhe district, the PCDD/Fs annual concentration (I-TEQ value) was 5295 fg/m~3 (240.1 fg I-TEQ/m~3). The concentration of atmospheric PCDD/Fs for Tianhe district was low in high temperature season, and high in low temperature season.The congener profile of atmospheric PCDD/Fs in Guangzhou was steady. The concentrations of OCDF, OCDD, 1,2,3,4,6,7,8-HpCDF and 1,2,3,4,6,7,8-HpCDD were relatively high, which accounting for more than 50% to total concentration. The contribution of 2,3,4,7,8-PeCDF to total I-TEQ was predominant with a range of 25%-40%. Steady congener profile suggested that the emission sources of PCDD/Fs in each area were fixed and no seasonal influence was observed. Emission sources of districts had correlation with their regional characteristic and function, which affected directly on regional atmospheric quality.The percentage of the different PCDD/Fs congeners associated with gas phase was increased with the number of chlorine decrease, ranging from 30% to 100% for 4CDD/Fs, about 50% for 5CDD/Fs and <20% for 6-8CDD/Fs.Of human risks via inhalation and daily intake in four districts in Guangzhou, inhabitants in Liwan district were highest. Especially for children, the daily intake for children was 4.1 pg I-TEQ/kg/day, and beyond the range for the tolerable daily intake of PCDD/Fs established by World Health Organization. In severely polluted day of Tianhe district, inhabitant's daily intake was possibly beyond the tolerable range. For example, the daily intakes for adults and children were 3.2 pg I-TEQ/kg/day and 4.3 pg I-TEQ/kg/day on Jan 6, 2006, respectively. Human health is probably threatened when there is some episode.The results showed that electric waste combustion, cooking exhaust and vehicle exhaust were main potential PCDD/Fs emission sources for Guangdong province. The concentration (I-TEQ) of three PCDD/Fs emission sources were 135666 fg/m~3 (7509.5 fg I-TEQ/m~3), 17826 fg/m~3 (1821.1 fg I-TEQ/m~3) and 5176 fg/m~3 (251.8 fg I-TEQ/m~3), respectively. Electric waste combustion was not only important PBDD/Fs emission source, but also for PCDD/Fs, which could affect on ambient air quality. The gas-particle partitioning of PCDD/Fs emitted from three emission sources was different because of different burning material, burning condition and burning degree. More than 90% PCDD/Fs presented in particle phase in cooking exhaust and vehicle exhaust. However, more than 30% PCDD/Fs were in gas phase in electric waste combustion emission, the proportion of the different PCDD/Fs congeners associated in gas phase was increased with the number of chlorine decrease.
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