Study On The Interaction Between Nano-Silver Particles And Chlamydomonas Reinhardtii In Water Environment

Nanomaterials,with the rapid development of nanotechnology,were inevitably released into aquatic environments in process of the production and application.Therefore,deep understanding of ecotoxicity,migration and transformation of nanomaterials released into aquatic environment can provide theoretical basis for the biogeochemical cycle and ecological risk assessment of nanomaterials.Meanwhile,these investigations are also conducive to promote the safe use of nanomaterials and the development of nanotechnology.Thus,Chlamydomonas reinhardtii was selected as a model organism to study the toxicity of typical artificial nanomaterials?AgNPs,60¹20 nm?on microalga.In addition,the effects of aquatic physicochemical properties on the fate of AgNPs in algae-containing water environments were also discussed.The main obtained conclusions are as follows:?1?The effects of AgNPs on the biomass and photosynthesis of C.reinhardtii indicated that the inhibitory effect of AgNPs on C.reinhardtii increased gradually and the photosynthetic pigment content in the cells decreased gradually with the increasing AgNPs level.The results indicated that AgNPs can affect their growth by inhibiting the photosynthesis of C.reinhardtii.?2?The effects of AgNPs on antioxidant enzymes and MDA in C.reinhardtii showed that,with the increasing level of AgNPs,the activity of SOD and CAT increased gradually,the activity of POD increased first and then decreased,the content of MDA increased gradually.The results indicated that AgNPs could cause the oxidative stress of C.reinhardtii,resulting in the destruction of its enzyme system.?3?The effects of AgNPs on the ultrastructure of C.reinhardtii showed that the ultrastructure of algae cells changed significantly and a large number of black particles accumulated in the cells.?4?The water chemical conditions had an effect on the fate of AgNPs in algae-containing waters environment.Increasing of the pH and HPO₄^2-would reduce the dissolution of AgNPs,the extracellular and intracellular absorption,and the bioavailable Ag content,which might reduce the toxicity of AgNPs.While,increasing of Ca²⁺would promote the dissolution of AgNPs,but reduce the extracellular and intracellular absorption,and the bioavailable Ag content,thus reduce the toxicity of AgNPs.Increasing the SRFA concentration would promote the dissolution of AgNPs,the extracellular and intracellular absorption,and the bioavailable Ag content,and thus enhance the toxicity of AgNPs.In sum,the ecotoxicity of metal nanoparticles was not only affected by its concentration,but also the chemical behavior of MNPs,which was affected by the water chemical conditions.