丙烯酰胺对水环境中典型微藻的毒性效应

Toxic effects of acrylamide on phytoplankton in natural waters

作为可疑致癌物,丙烯酰胺(acrylamide,AM)是目前各国政府和广大民众普遍关注的重要污染物.为探究AM对水体生物的毒性效应及可能存在的生态风险,本文以海洋微藻东海原甲藻(Prorocentrum donghaiense)和淡水微藻莱茵衣藻(Chlamydomonas reinhardtii)为研究对象,采用室内培养法,测定了不同暴露浓度的AM对2种微藻生长、形态和生理状态的影响.结果显示,AM对2种藻类生长均有显著的抑制作用(P<0.05),96 h半抑制质量浓度(EC50)分别为22.79 mg·L^-1和161.8 mg·L^-1;最高无抑制浓度(NOEC)分别为1.04 mg·L^-1和9.84 mg·L^-1.不同微藻对AM胁迫的响应存在较大的差异性,与莱茵衣藻相比,东海原甲藻对AM更敏感.扫描电镜(SEM)和透射电镜(TEM)结果显示,当受到AM影响时,2种藻细胞严重变形,表现出塌陷、质壁分离、空泡数量增多和叶绿体片层结构少量断裂等现象;叶绿素含量和Fv/Fm(PSⅡ最大光化学量子产量)测试表明AM可以通过破坏微藻的光合系统而抑制光合作用.AM对东海原甲藻属于中毒性物质,对莱茵衣藻属于低毒性物质.

Acrylamide(AM),as a suspected carcinogen,is an important pollutant concerned by governments and the general public.To explore the toxic effects and associated mechanisms of AM on algae growth,marine algae(Prorocentrum donghaiense)and freshwater algae(Chlamydomonas reinhardtii)were investigated by determining various physiological and biochemical parameters,such as cell abundance,cell morphology,chlorophyll content and maximum photosystemⅡ(PSⅡ)quantum yield(Fv/Fm)under controlled laboratory conditions.The results demonstrated that the growth of the two algae were inhibited significantly by AM at 96 h(P<0.05).Half maximal effect concentrations(EC50)for P.donghaiense and C.reinhardtii were 22.79 mg·L^-1 and 161.8 mg·L^-1,and no observed effect concentration(NOEC)for P.donghaiense and C.reinhardtii were 1.04 and 9.84 mg·L^-1,respectively.P.donghaiense was more sensitive to the toxicity of AM,while C.reinhardtii was more tolerant.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)showed that 50 mg·L^-1 AM exposure caused visible cell deformation,plasmolysis,and disintegration of chloroplasts.Chlorophyll content and Fv/Fm showed that AM could inhibit photosynthesis by destroying the photosynthetic system of microalgae.AM had medium toxicity to P.donghaiense,and low toxicity to C.reinhardtii.