多環芳香烴化合物對藻類之光毒效應研究

Abstract

本研究利用BOD瓶進行密閉式藻類（Raphidocelis subcapitata）毒性試驗評估PAHs光變化產物之毒性，且分析月芽藻對Anthracene 光誘導毒性的光合作用機制。 本實驗主要量測三種反應終點，包括溶氧變化量(△DO)，以藻類細胞密度變化量計算所得的最終產量（Final yield）及生長率(Growth rate)。ANT的光產物毒性較原ANT毒性更毒，其中以1,8-dhATQ為最毒，而ISO則毒性最低。ANT經UV-A照射後會迅速光變化，形成較具水溶性產物且對藻類毒性更毒。比較ANT光誘導毒性，毒性可在生長率上增加10倍，此外ANT 經6小時光UV-A曝露後，會轉變為ATQ、1-hATQ與單環芳香族。而ANT經24與48小時UV-A後，ANT會進一步光變化產生1,8-dhAT 與 1,4-dhATQ。在物種之間的敏感度比較上，藻類毒性試驗比浮萍敏感。本研究發現藻類敏感度會受一些因素的影響，這對以後藻類抑制反應提供寶貴資料。 此外本研究以平均中斷值（cut-off value）作為選擇NOEC或EC10的客觀參考點，結果顯示NOEC比EC10提供生物更嚴謹的保護標準。

In this study, we use BOD bottles to perform a close-system algal(Raphidocelis subcapitata) test to assess the toxicity of PAHs photomodification products. we also analyze the photosynthesis mechanisms associated with photoinduced toxicity of anthracene to R.subcapitata The toxic test was ended based on DO, final yield and growth rate methods. The cell density difference was used to calculate the final yield and growth rate. ANT photoproducts those were more toxic than the parent compound. The most toxic was 1,8-dhATQ. In contrast, ISO was the least toxic. ANT are rapidly photomodified in UV-A to products that are more water soluble and toxic to R. subcapitata. Compared to ANT photo-induced toxicity, toxicity was increased 10 times on GR. Furthermore, ANT was converted to ATQ, 1-hATQ, and one-ring aromatics after 6 h of UV-A exposure. After 24 and 48 h UV-A, photomodification of ANT had further generated of 1,8-dhATQ and 1,4-dhATQ. When compare with other species, BOD bottle test shows a higher sensitivity and a good correlation with the Duckweed assays. This study derives that sensitivity of the algae can be influenced with different major factors, and show precious data about the algae inhibition toxicity test. In addition, a cut-off value approach is proposed to determine whether NOEC or EC10 should be chosen for estimating low toxic effects. The results indicate that NOEC offers better protection to test organisms than EC10.