| 摘要: | 由於二仁溪流域的家庭和畜牧廢水排放及其支流三爺宮溪至下游沿岸的工廠所造成的污染，使二仁溪成為全台灣污染最嚴重的河川，且污染河段有擴大趨勢；而多氯聯苯是環保署優先列管的毒性物質，在過去的研究中也證實存在河川的底泥當中；在二仁溪中，研究中顯示其下游三爺宮溪至出海口段比其它河段的多氯聯苯含量高出釵h。
本研究就二仁溪下游流域，以南萣橋為中心，區分以下三個區域：（一）二仁溪北側三爺宮溪至南萣橋（二）二仁溪北側南萣橋至出海口（三）二仁溪南側南萣橋至出海口，採集內側（靠堤防）及外側（靠河道）不同位置之底泥，將採得之底泥分為表層底泥(0~20公分)、中層底泥(20~40公分)及深層底泥(40~60公分)，針對不同深度之底泥進行多氯聯苯含量調查，以分析二仁溪下游流域河段之不同深度之底泥多氯聯苯含量的分佈情況。
為了研究南台灣河川底泥中多氯聯苯（PCBs）污染物，在2005年10月及2006年12月分別從6個位址採集不同地層（表層至深層在0~60公分深度）的底泥，在萃取之後以GC分析，結果顯示在較深層的多氯聯苯（PCBs）濃度高於表層的多氯聯苯（PCBs）濃度，而且下游處比上游處高；在所有樣本中多氯聯苯（PCBs）總濃度範圍在0~2.718ppm之間，其中含量最多的同類異構物為2,5,2’-CB，2,4,3’,4’-CB，2,5,3’,5’-CB，2,3,6,3’,4’-CB，2,4,5,3’,4’-C和 2,3,4,5,2’,3’,4’-CB，在這些同類異構物中，有5~6個氯之高含氯量的來自於Aroclors，而3~4個氯之低含氯量的可能從高含氯量多氯聯苯（PCBs）的脫氯作用而來；此外，在最下游處的深層底泥其多氯聯苯（PCBs）污染物的分佈與Aroclors1242及Aroclors1254的同類物較為相似；從時間上的次序比較多氯聯苯污染物的分布與濃度，其結果發現最近幾年多氯聯苯的脫氯作用表面上有受到抑制且其殘留的污染物有向大海移動的情況。
本研究可以發現二仁溪下游流域中以二仁溪南側南萣橋至出海口段多氯聯苯濃度含量較高而二仁溪北側三爺宮溪至南萣橋段內側（靠堤防）底泥多氯聯苯含量較低，且由高污染濃度地點之分布可以看出，多氯聯苯向下游移動，並有擴散至出海口的趨勢。
Erh-Jen river basin had been contaminated by domestic and stock farming waste water, and the tributary San-Ye-Gung creek also polluted by industrials the fact in down river.After decades of uncontrolled discharging Erh-Jen river became the most heavily polluted river in priority Taiwans, and the pollution had the tendency to expand. Polychlorinated biphenyls（PCBs）were considered as the hazardous chemacal controlled by the environmental protection administration.This group of compounds was verified and stored in the bottom mud in the rivers and creeks in the past research.
In order to investigate polychlorinated biphenyls(PCBs) contamination in the river sediment in southern Taiwan. Different layers (the upper layer to the lower layer,0~60cm in depth) of sediments from 6 locations were collected in October,2005 and December, 2006, separately. After extraction and GC analysis, the results showed the PCBs concentration in the lower layers were higher than the upper layers, and in the downstream locations were higher than the upstream locations. The total PCBs concentration of all samples were range from 0~2.718 ppm. 2,5,2’-CB-chlorobiphenyl (2,5,2’-CB), 2,4,3’,4’-CB, 2,5,3’,5’-CB, 2,3,6,3’,4’-CB, 2,4,5,3’,4’-CB and 2,3,4,5,2’,3’,4’-CB were the most abundant congeners. Among these congeners, the highly chlorinated ones with 5~6 chlorines were originated from Aroclors, and the less chlorinated ones with 3~4 chlorines were possibly from the dechlorination of highly chlorinated PCBs. Except the lower layer of the most downstream site,the layers with significant PCBs contamination showed the similar congener distribution with Aroclor 1242 and 1254. By comparing the concentration and distribution of PCBs contaminant in a sequence of time,the results suggested that the dechlorination of PCBs was seemingly inhibited in recent years and the persisted PCBs contamination was moving toward the sea. |
