| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 95 === Dioxins are persistant organic pollutants in the environment and have diverse toxic occur in living organisms. The events of dioxins toxication and dioxins pollution happened in Taiwan constantly. Although the government sets up the emission standard and emission inventory to control the dioxins, the effective management requires more comprehensive understanding of dioxins flow in the economy and the environment.
The substance flow of dioxins of Taiwan is investigated in this study and the framework of substance flow network is defined. Uncertainty analysis and multimedia model (CalTOX) are combined to increase the accuracy of estimation of the flow in the environment.
The results show that dioxins are discharged on average 2480.19 (589.18 ~8593.50) g I-TEQ, including 256.31 (98.50 ~628.88) g I-TEQ to air, 2197.46 (606.15~7084.76) g I-TEQ in the residues, 21.97 (6.06~70.85) g I-TEQ to soil, and 2.07E-06 (1.08E-07~6.28E-06) g I-TEQ to water. Dioxins in the food are also estimated. There are 0.57 (0.29~0.88) g I-TEQ in imported foods, 0.74 (0.09~1.76) g I-TEQ in exported foods, and 1.78 (0.44~3.86) g I-TEQ in the animal husbandry in Taiwan.
The contributions of the sources of dioxins discharge in order are electric arc furnaces (41.42%), ferrous foundries (12.32%), industrial waste incineration (11.0%), and sintering plants (7.30%).
The fate of most dioxins in the environment is stored in root soil (52.70%); others are in air (0.13%), leaf (1.01%), cuticle (0.98%), ground-soil (1.75%), vadose-zone soil (24.74%), surface water (0.01%), aquifer (5.20%), and sediment (13.19%).
The study also conducts a scenario simulation, according to the dioxin emission standard modified from 2004 to 2008 and activity intensities that grow 10%. Although the amount of dioxins increases 0.71%, the dioxins emitted from flue reduces 40.27%. It shows the modification of dioxin emission standard has effect.
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