| 摘要: | 本研究採集南台灣二仁溪下流流域之底泥6處，將採得之底泥分為表層底泥(0~30 公分)及深層底泥(31~60 公分)，針對不同深度之底泥進行多氯聯苯含量分析調查，A點表層底泥(0~30 公分)全部多氯聯苯濃度總合為4.814 μM，其中以2,3,6,3',4'-CBp 15.25%佔的百分比最多，次之是2,4,3',4'-CBp 13.74%及2,4,5,3',4'-CBp之13.47%。 A點深層底泥(31~60 公分)全部多氯聯苯濃度總合為1.676 μM，其中以23452'3'4'-CBp, 38.89%佔的百分比最多。B、C兩點表層底泥(0~30 公分)及深層底泥(31~60 公分)並無出現任何多氯聯苯。D點表層底泥(0~30 公分)以253'5'-CBp, 12.41%所佔百分比最高，252'-CBp, 11.76%次之。D點深層底泥(31~60 公分)以23452'3'4'-CBp, 26.20%所佔百分比最高，其次是242'5'- CBp, 15.74%。E點表層底泥(0~30 公分)以262'-CBp, 47.31%所佔百分比最高，其次是23452'3'4'-CBp, 25.25%。E點深層底泥(31~60 公分)以252'-CBp, 17.62%所佔百分比最高，其次是253'5'-CBp, 12.07%。F點表層底泥(0~30 公分)以23452'3'4'-CBp, 93.19%所佔百分比最高，而F點深層底泥(31~60 公分)， 23452'3'4'-CBp, 21.69%所佔百分比最高，其次是252'-CBp, 7.85%；各點之污染狀況與Aroclor 1242近似，皆有較低氯數之多氯聯苯的存在。
此外本研究建立模擬箱模擬環境中多氯聯苯之脫氯情形，土壤管柱中添加234-CBp、253'4'-CBp、242'5'-CBp、2452'4'5'-CBp及Aroclor 1242，經過3個月的置放培養後，發現234-CBp濃度皆有降低的現象；也發現有24-CBp的脫氯產物，證實模擬箱中234-CBp管柱中有明顯的脫氯作用存在。253'4'-CBp及242'5'-CBp濃度皆有降低的現象；而在253'4'-CBp發現在11~15cm及21~25cm有342'-CBp的脫氯產物，242'5'-CBp之管柱也發現在16~20cm有24'-CBp, 0.1415 μM及發現252'-CBp, 1.1745 μM的脫氯產物。
2,4,5,2',4',5'-CBp發現有部分242'5'-CBp、242'4'-CBp、2,4,5,2',5'-CBp及2,4,5,2',4'-CBp脫氯產物，因此2,4,5,2',4',5'-CBp應有脫氯作用的發生。
In order to investigate polychlorinated biphenyls (PCBs) contamination in the river sediment in southern Taiwan, every 2 layers (the upper layer 0 ~ 30 cm, and the lower layer 30 ~ 60 cm, in depth) of sediments from 6 different sites were collected and analyzed the PCBs content. The results showed that in the upper layer of Site A, total PCBs concentration was 4.814 M, 2,3,6,3’,4’-chlorobiphenyl (2,3,6,3’,4’-CB) was the most abundant congeners with a ratio of 15.25 %, and 2,4,3’,4’-CB and 2,4,5,3’,4’-CB were 13.74 %, 13.47 %, respectively. In site B and site C, there was no significant PCBs contamination. In Site D upper layer, 2,5,3’,5’-CB and 2,5,2’-CB were the major congeners with 12.41% and 11.76 % of weight ratio. Similar to the lower layer of Site E, 2,5,2’-CB and 2,5,3’,5’-CB were two most abundant congeners. However, in Site F lower layer, 2,3,4,5,2’,3’,4’-CB was congeners with the highest concentration of 21.69%, then 252'-CBp was of 7.85%. Except Site F lower layer, most of the layers with significant PCBs contamination showed the similar congener distribution with Aroclor 1242.
While the investigation of PCBs contamination was completed, a Simulated Aquarium Box (SAB) was constructed in a purpose of evaluating PCBs dechlorination in natural sediment environment. Sediment columns amended with different PCBs congeners or mixture such as 2,3,4-CB, 2,5,3’,4’,-CB, 2,4,2’,5’-CB 2,4,5,2’,4’,5’-CB and Aroclor 1242 were introduced into SAB for PCBs dechlorination tests. After 3 months of incubation, 2,3,4-CB concentration decreased and 2,4-CB was found. It suggested that PCBs dechlorination happened in the sediment. In 2,5,3’,4’-CB and 2,4,2’,5’-CB columns, the concentration were both decreasing, and their dechlorination products, 3,4,2’-CB and 2,5,2’-CB were also produced. 2,4,5,2’,4’,5’-CB, a congener with 6 substituted chlorines was thought not easily dechlorinated, however in SAB, it’s dechlorination product such as 2,4,2’,4’-CB, 2,4,2’,5’-CB and 2,4,5,2’,4’-CB, 2,4,5,2’,5’-CB were produced during a 3 months of incubation. |
