聚苯乙烯奈米塑膠顆粒在海水或淡水中的毒性差異及加上二苯甲酮-3共處理後在海水中對青鱂魚的影響

Abstract

隨著科技的發展，塑膠製品的大量使用造成環境中越來越嚴重的塑膠污染已在近年成為人們關注的重大問題。另一項受到眾人矚目的汙染源則是市售防曬乳中常見的化學添加物:二苯酮家族，其中又以二苯甲酮-3（Benzophenone-3, BP-3）的防曬效果最好，但其毒性也最大。不管是塑膠垃圾分解後形成的塑膠顆粒或是BP-3等添加物，對於海洋的影響都最為深遠，但現行研究多半著重於兩者對淡水脊椎生物的影響，針對海水脊椎動物的研究數量卻是遠遠不及。有鑑於此，本研究選擇青鱂魚（Oryzias latipes）作為本研究的模式動物，利用青鱂魚的廣鹽性，比較聚苯乙烯奈米塑膠顆粒（Polystyrene nanoplastic particles, PS-NPs）在海水中和淡水中是否會對魚類造成不同程度或不同類型的傷害。除此之外本研究也針對海水環境分別測試PS-NPs和BP-3以及在共處理情況下這些物質對胚胎早期發育的影響。首先，我們使用了0、10、25和50 ppm四種不同濃度的PS-NPs處理，分別在海水及淡水環境下進行實驗，結果顯示在海水環境50 ppm組別中發現死亡率有顯著上升，且海水處理下的25和50 ppm組別中發現，樣本的表皮離子細胞數目有顯著減少，細胞分泌的氫離子和氯離子也被抑制。淡水處理下則是在25和50 ppm組別中觀察到樣本的側線毛細胞數量顯著減少，同時在25 ppm組別中觀察到胚胎的活動力下降。而BP-3的實驗，我們將胚胎暴露在含0、0.005 % DMSO、1、3和5 ppm BP-3的海水中，結果顯示在含有BP-3的海水中暴露8天後，雖然不會造成胚胎死亡，但3 ppm和5 ppm處理組在個體長度等早期發育指標及離子細胞、毛細胞數量上有顯著下降。在共處理的情況下，則是透過控制組、3 ppm BP-3、25 ppm PS-NPs及3 ppm BP-3加上25 ppm PS-NPs的共處理組互相比較，我們發現和單純暴露於BP-3的組別相比，共處理組中兩個變因對胚胎的影響反而變小。總結以上結果，PS-NPs在淡水與海水中會呈現不同強度或不同面向的傷害；BP-3則會造成發育遲緩和離子細胞、毛細胞的數量下降；但共處理後，BP-3因受到PS-NPs的影響，毒性會減弱。

With the development of technology, the widespread use of synthetic plastic products has resulted in increasingly severe plastic pollution in the environment. These potential biological hazards have become a major concern in recent years. Another potential pollutant that caught the public’s attention is the benzophenone class - chemical additives commonly found in commercially available sunscreens, of which benzophenone-3 (BP-3) is the most effective ultraviolet absorber and has also stirred up the most controversy. However, most previous studies focused on the effects on freshwater vertebrates, while the number of studies on marine vertebrates is far smaller. In this study, medaka (Oryzias latipes) was used as the model animal because of its broad salinity tolerance. The first part of this study compared the different levels or types of damage caused by polystyrene nanoplastic particles (PS-NPs) in fresh and seawater environments. The second part focused on the effects of PS-NPs and BP-3 on the early development of embryos in a seawater environment. The results showed that although previous studies have generally concluded that neither micro-particles nor nano-particles are lethal, a significant increase in mortality rate was found in the 50 ppm group in both freshwater and seawater, while significant decreases in the number of epidermal ionocytes and inhibition of cellular H+ and Cl- secretion were also found in the 25 and 50 ppm groups in seawater. In the freshwater groups, significant decreases in the number of lateral line hair cells were observed in the 25 and 50 ppm groups, and a decrease in the motility of embryos was observed in the 25 ppm group. On the other hand, after exposing embryos to seawater containing BP-3 for 8 days, no death was observed, but there was a significant decrease in early developmental indicators and other indicators such as the number of ionocytes and hair cells in the 3 ppm and 5 ppm groups. In the group where the water contained both BP-3 and PS-NPs, the effects of these two substances on embryos were less significant compared to the group exposed to BP-3 alone. These results indicate that PS-NPs in freshwater and seawater exhibit different intensities or types of damage. BP-3 caused developmental delays and decreases in the number of ionocytes and hair cells.