以密閉式藻類毒性試驗評估極性麻醉有機物之毒性

Abstract

本研究以藻類（Raphidocelis subcapitata）利用BOD瓶進行一密閉式系統之毒性試驗，評估苯胺類之極性麻醉有機物之毒性，以及討論同屬於極性麻醉有機物之酚及氯酚類的毒性機制。 本實驗主要量測兩種反應終點，包括溶氧變化量(Based On DO)以及代表生物質量(Based On Biomass)的藻類細胞密度變化量，而為了提高毒性數據的可信度也以G test進行合適度分析，選擇最佳模式以計算其EC值。在本次毒性試驗中可發現取代基對於毒性所造成的影響，隨者取代基的增加，毒性有增強的趨勢，而取代基的位置不同也會造成不同的毒性。在物種之間的敏感度比較上，藻類毒性試驗與Microtox相比敏感度相近，而與原生動物或次粒腺體的毒性試驗相比則敏感度多數較佳，顯示藻類毒性試驗具有良好的敏感度。此次研究也對於毒性物質的QSAR(Quantitative Structure-Activity Relathionship)進行研究，並成功的建立起包含疏水性及氫鍵鍵結能力兩項物化參數的QSAR預估模式，可用於預測此類有機物對藻類所造成的毒性。 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。

The effects on algal(Raphidocelis subcapitata) inhibition of 13 substituted anilines were recorded by using a close-system BOD bottle test, the mechanism of substituted anilines and chlorophenols were discussed which were both considered as polar narcotics. The toxic test was ended based on DO and Biomass Methods. The Biomass Method was to calculate the cell density difference between the start and the final points. EC values were calculated using the appropriate model chosen from G-test. In this study, the toxic effects caused by substituted anilines were found to related to the numbers and positions of substitutents. With increasing of the substitutents, substances were found more toxic to algal. When compare with other species, BOD bottle test shows a similar sensitivity with Microtox and a good correlation was found in particular with another widely used assays system, the Tetrahymena assays. Quantitative structure-activity relationships (QSARs) were established between the EC50 values and various molecular descriptors for hydrophobic and hydrogen-bond interactions, and a highly predictive two-variable QSAR model was obtained. 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.