台灣戴奧辛物質流分析

Abstract

戴奧辛號稱「世紀之毒」，台灣歷年來也有許多戴奧辛中毒及污染事件，對戴奧辛的管理則多琢磨在訂定排放標準以及建立排放清冊，雖然能於源頭減量並掌握每年戴奧辛排放趨勢，但對於戴奧辛的管理還不夠全面性，並且對於戴奧辛在環境中的流佈狀況也未善加瞭解。 本研究使用物質流分析，架構出台灣戴奧辛流佈狀況，並結合不確定性分析，考慮參數的不確定性，提高戴奧辛排放分佈估算的準確性。另外也使用CalTOX多介質模式，瞭解由經濟圈所排放的戴奧辛在環境圈中的分佈狀況。 研究結果顯示，台灣經濟圈戴奧辛整體釋放量為2480.19 g I-TEQ (589.18~8593.50 g I-TEQ)，有256.31 g I-TEQ (98.50~628.88 g I-TEQ)經煙道釋放到空氣，2197.46 g I-TEQ (606.15~7084.76 g I-TEQ)儲存在廢棄物，並有21.97 g I-TEQ(6.06~70.85 g I-TEQ)釋放到土壤，以及有2.07E-06 g I-TEQ (1.08E-07~6.28E-06 g I-TEQ)釋放到水體。並且計算貿易食品及境內產品所含戴奧辛量，進口食品為0.57 g I-TEQ(0.29~0.88 g I-TEQ)，出口食品為0.74 g I-TEQ(0.09~1.76 g I-TEQ)；自給畜產為1.78 g I-TEQ(0.44~3.86 g I-TEQ)。 而戴奧辛排放貢獻量依序為電弧爐(41.42%)、集塵灰回收設施(12.36%)、鑄造廠(12.32%)、事業廢棄物焚化爐(11.0%)、燒結廠(7.30%)。 戴奧辛由經濟圈釋放後的環境宿命，最終以儲存在土壤為主，尤其是根部土壤，佔52.70%的比例，另外在空氣(air)佔0.13%，植物體(leaf)佔1.01 %，植物表皮(cuticle)佔0.98%，表土(ground-soil)佔1.75%，深層土(vadose-zone soil)佔24.74%，表面水(surface water)佔0.01 %，地下水佔5.20 %，底泥(sediment)則佔13.19%。 本研究更進一步做情境假設，以所建立的戴奧辛物質流資料庫為基礎，並根據台灣在2004~2008年間所修改戴奧辛排放標準，可知在活動強度成長10%下，若能確實遵守所修改的戴奧辛排放標準，雖然整體戴奧辛量增加0.71%，但在經由煙道排放的戴奧辛則能有40.27%的減量較果，可知戴奧辛排放標準的修訂具有一定的成效。

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.