以密閉式藻類毒性試驗評估多環芳香烴化合物之光誘導毒性效應

Abstract

本研究利用BOD瓶針對UV光照前後之11種PAHs 進行密閉式藻類毒性試驗，比較其光照前後毒性差異進而判別其光誘導毒性效應之影響。實驗結果顯示五環之B[b]C毒性最強，兩環Nap之毒性最弱；光毒實驗部份則發現本研究之11種PAHs其中有六組會產生光誘導毒性造成其光照後毒性明顯增強的現象，分別為Ben, Flu, Ant, B[a]A, Acr, Per六種。而本研究敏感度最高之試驗終點為最終產量。 QSAR預測光毒之部分，本研究依HOMO-LUMO gap與光照前後之EC50 比值迴歸所建立之光毒窗預測範圍，在以生長率為試驗終點時△GAP值分佈在6.7~7.9 ev時具光毒性，而另外兩種試驗終點亦得到十分相近之結果。此外由中斷值（cut-off value）分析結果發現三參數下之平均中斷值皆小於10%，顯示本研究之PAHs無論光照前後皆以NOEC值能提供比EC10更好的保護標準。關於其它QSAR分析參數則是發現PAHs與水及辛醇係數有良好之相關性，可做為預測毒性之參考。 此外在物種比較的部份發現藻類毒性試驗敏感度皆較柵狀藻 (Scenedesmus subspicatus)、鯉魚(Fathead minnow)、鱒魚(Rainbow trout)要高，並與鯉魚(Fathead minnow)試驗結果有極高之相關性。

The effects on algal (Pseudokirchneriella subcapitata) inhibition of 11 PAHs between dark and light conditions were assessed by using a close-system BOD bottle test , and evaluated the effect of phototoxicity. The result show that B[b]C is the most toxic compound and the toxicity was risen by increasing the number of rings. Six compounds reveals obvious phototoxic after the irradiation of UV lights among the 11 PAHs of our test. They are Ben , Flu , Ant , B[a]A , Acr , Per. Besides, the most sensitive end point in our test is FY. The prediction of phototoxicity by QSAR in our test is established by the HOMO-LUMO gap and the EC50 ratio between dark and light. The △GAP distributed over the range of 6.7~7.9 ev exhibits phototoxic base on growth rate. The other two of the end points show the similar results. In addition, the results indicates that NOEC offers better protection to test organisms than EC10 by observation of the cut-off value. With regard to other parameters we found that there are good correlation between LogP and the result of our test. The BOD bottle test shows a greater sensitivity than other species and a good correlation was found in comparison with the fish (Fathead minnow).