| 摘要: | 本研究主要目的在於測試二仁溪自然環境底泥中六氯苯(Hexachlorobenzene, HCB)的移動與降解等環境命運，研究採集二仁溪南萣橋上下游兩區段的河川底泥作為實驗主體，依處理方式區分為四個研究區塊，其個別實驗結果顯示：
(1) 在底泥水中添加不同濃度的HCB，分別為2 ppm、10 ppm兩種，其中2 ppm低濃度的HCB，上游微生物只能降解30~36%，殘餘濃度約1.3 ppm，就會停滯，而下游底泥微生物之降解可達42%到48%，殘餘濃度約為1.1 ppm。而10ppm高濃度HCB的組別，上游底泥微生物可降解到70%左右，換算殘餘濃度約為2.8 ppm，下游底泥降解率64%，殘餘濃度約3.6 ppm。
(2) 在上游及下游底泥中添加HCB達2ppm、20ppm兩種濃度，2 ppm組別於上游底泥中降解達68%，下游底泥降解達73%。20 ppm組別於上游底泥中降解達64%，下游底泥降解達72%。
(3) 進行HCB移動與降解測試之環境流布實驗結果發現，將受測底泥分為上、中、下共三層，下層與中層的降解結果差不多，而上層受到曝氣影響而導致降解成果不如中、下兩層(4) 定期定量添加HCB進行模擬擴散測試，每週在底泥環境模擬槽中添加達0.1 ppm 之HCB，到第八週在上層底泥也驗出1.56 ppm濃度，在第十六週時驗出上層有3.68 ppm，而中層底泥僅於第十二週驗出0.14 ppm、第十六週驗出0.58 ppm。代表HCB會經有水流而擴散，並在底泥中沉積後，且有往中層擴散之跡象。
The main purpose of this study is dedicated to test the environmental fate of Hexachlorobenzene (HCB) in the sediments of Er-Ren River natural environment. The river sediments in the upstream and downstream areas of Nan-Din Bridge were collected as the subjected matrix. According to the processing methods, it is divided into four researches, and the individual result showed:
(1) Amending HCB in the sediment waters to reach a final concentrations of 2 ppm and 10ppm respectively, the sets of 2 ppm HCB showed 30~36% of HCB degradation by the upstream sediment microorganisms, and 1.3 ppm of the residual concentration. Meanwhile, downstream microorganisms could reach 42% to 48% of HCB degradation, and get the residual concentration of 1.1 ppm. In the sets of 10 ppm amendment, the upstream microorganisms could degrade HCB to about 70% with the residual concentration about 2.8 ppm, the downstream’s degradation was about 64%, and the residual concentration was about 3.6 ppm.
(2) In the sets of amending HCB in the river sediments to a concentration of 2 ppm, HCB was 68% degraded in the upstream sediment and 73% in the downstream sediment. And in the sets of 20 ppm amendment, HCB was 64% degraded in the upstream sediment and 72% in the downstream sediment.
(3)The movement and degradation tests of HCB were constructed by divided tested sediments into three layers (upper, middle and lower). And the degradation results showed similar HCB degradation within the lower layer and the middle layer, however, the upper layer was less-degraded with the inhibition of the oxygen.
(4) In environmental distribution tests of HCB by adding 0.1 ppm of HCB per week to the Simulated Aquarium Boxes (SAB), 1.56 ppm of HCB was first found in the upper layer sediment after eight weeks of treatment. At the 16th week, 3.68 ppm HCB was detected in the upper layer. As well as 0.14 ppm HCB was first detected in the middle layer at 12th week and 0.58ppm at 16th week. No HCB was found in the lower layer with 16 weeks. It suggested that HCB will transport by the water flow and deposit in the surface of sediment, but not significantly diffuse into the lower and bottom layers. |
