壬基酚对胶州湾典型微藻的毒性效应

以胶州湾常见优势藻种中肋骨条藻(Skeletonema costatum)和旋链角毛藻(Chaetoceros curvisetus)为受试生物,考察了壬基酚(NP)对两种海洋微藻的急性毒性效应,同时以超氧化歧化酶(SOD)活性和丙二醛(MDA)含量为指标,研究了两种海洋微藻细胞内抗氧化系统对NP氧化胁迫的响应。结果表明,NP对中肋骨条藻和旋链角毛藻生长抑制的96 h-EC50分别为0.13 mg/L和0.22 mg/L,中肋骨条藻对NP的毒性更为敏感。当中肋骨条藻培养体系中NP浓度在0.04～0.16 mg/L和旋链角毛藻培养体系中NP浓度在0.05～0.20 mg/L时,两种海洋微藻体内SOD活性均呈现出先诱导上升后抑制降低的变化趋势,MDA含量则随NP浓度的增大而增大;而在低浓度NP(<0.05 mg/L)胁迫下,96 h实验周期内,两种微藻细胞内SOD活性和MDA含量与不添加NP的对照组相比无显著差异(P>0.05),表明低浓度的NP胁迫下微藻体内诱导产生的抗氧化酶能够及时清除活性氧自由基,防止细胞受到损伤。暴露实验72 h后,两种微藻细胞内的SOD活性和MDA含量与NP作用浓度呈现显著的浓度-效应关系,这表明微藻细胞内SOD活性和MDA含量可以作为生物标志物用于近海水体中NP生态风险评价。

Toxic effects of nonylphenol on dominant microalgae species in Jiaozhou Bay

The toxic effects of nonylphenol(NP) on two dominant microalgae species of Skeletonema costatum and Chaetoceros curvisetus in Jiaozhou Bay were studied.In the meanwhile,the antioxidant responses of two kinds of microalgae cells to NP stress were also investigated by SOD and MDA activities as the index of antioxidant status.The results showed that 96 h-EC50 values of NP to S.costatum and C.curvisetus were 0.13 mg/L and 0.22 mg/L,respectively.The response of S.costatum was more sensitive to NP toxicity than that of C.curvisetus.SOD in two kinds of microalgae cells were activated firstly,and then inhibited.The content of MDA was increased significantly with the increase of NP concentration.On the other hand,there was no significant difference in SOD and MDA levels between the blank control groups and the treatment groups with low dosage below 0.05 mg·L-1(P>0.05),which showed that the reactive oxygen free radical could be scavenged immediately by antioxidant enzymes,which were induced by low NP stress on microalgae cells.There was a significant dose-response correlation between the concentration of NP and the activities of SOD and those of MDA in the two kinds of microalgae cells after within 72 h of exposure,which showed that SOD and MDA in microalgae cells may be as biomarkers for evaluation of NP contamination in coastal seawater.