The Fate Of Silver Nanoparticles In Microcosm And Its Toxicity Effects On Corbicula Fluminea

In recent years,silver nanomaterials?AgNPs?have been widely used in production and daily life,which have brought great convenience to social development.Therefore,it is inevitable that AgNPs enter into aquatic environment in the process of production,manufacture,use and abandonment,which may affect the safety and health of aquatic organisms and aquatic environment.Once AgNPs released from commodities into aquatic environment,most AgNPs sedimented into sediment or bioacccumulated in biotas due to the physicochemical interaction and biological effect.Therefore the toxicity effect of AgNPs on benthic organisms ha s drawn widely attention.As a vital part of benthic organisms,filter-feeding bivalves not only play a vital role in the structure and function of marine and estuarine ecosystems,but also can be used as a typical sentinel for environmental pollutants.However,a lot of researches focused on the impact of AgNPs on marine bivalves,and there is only a little study about the impact of AgNPs on freshwater bivalves.S o the toxicity effect of AgNPs on freshwater bivalves deserves further study.In this study,polyvinylpyrrolidone?PVP?coated AgNPs was selected as a typical silver nanomaterials.Corbicula fluminea?C.fluminea?was chosen as a typical freshwater bivalve for further understanding the toxicity effect of AgNPs on freshwater bivalves.In order to investigating the fate of AgNPs in experimental system,the bioaccumulation and toxicity effects of PVP-coated AgNPs on C.fluminea,a series of experiments in artificial ecosystem with different concentrations(0,0.1,0.5,2 mg·L^-1)were conducted.According to the results,C.fluminea played an important role in promoting the deposition of AgNPs into sediment.C.fluminea showed a good tolerance to different concentrations of AgNPs,in addition,the tissues of C.fluminea had strong sensitivity to AgNPs under the low concentrations.AgNPs had a long retention time in the tissues of C.fluminea,which may cause long-term toxicity effects on C.fluminea.According to the toxicity experiments,C.fluminea showed different antioxidant mechanisms to different AgNPs concentrations.The feeding rates and ammonia rates of C.fluminea were inhibited at 0.1 mg·L^-1 without lipid peroxidation;Tissues of C.fluminea were protected from damage by the increasing level of GSH at 0.5 mg·L^-1;At 2 mg·L^-1 AgNPs,C.fluminea were under strong oxidative stress,furthermore,its feeding and metabolic capability were weaken;The antioxidant defense mechanism of C.fluminea was activated and can protect tissues from oxidative damage by regulation of antioxidant enzymes?SOD,CAT,GST,GPx?and the enzymes of antioxidant?GSH?.