Study On The Fate Of Silver Nanoparticles In Acquatic Eco-system Using The Microcosm Model

Nanomaterials are widely used in many fields of our life because of the superiority.Silver nanoparticles(AgNPs)are one of the most widely used nano-materials.However,the migration and fate of AgNPs in aquatic ecosystem and its impact on aquatic ecosystem have become a hot spot in the world.A pond microcosm model was constructed,which contained sediment,water,black algae,snails and fish.This aquatic ecosystem was more similar with the true environment.AgNPs were added into the system by the modes of single high-concentration addition,multiple lowconcentration AgNPs addition,as well as increasing fish disturbance.The migration mode of AgNPs in water environment and the enrichment characteristics in aquatic organisms were investigated.The environmental effects of silver nanoparticles were also clarified.The main research contents and results are as follows:(1)After the addition of AgNPs,nitrogen,phosphorus,organic carbon,temperature and pH were not significantly different from those in the control group.The release rate of nitrogen and phosphorus in the model with fish disturbance was higher than that in the control group without fish disturbance.(2)The concentration of AgNPs in water decrease with time in the single high-concentration addition group,and the concentration of AgNPs increased firstly with each multiple lowconcentration addition.The deposition rate of AgNPs was higher in the system with fish disturbance than that without fish disturbance.AgNPs were more likely to be deposited in the bottom sediment rather than suspended in water.(3)There was no significant difference in biomass of snails,fish and black algae in every group.The highest concentration of silver was found in snails(8.6 ?g/g),which was 2.35 ~ 2.99 times as much as that in black algae,and 1.22 ~ 1.52 times as much as that in fish.Due to the difference in effective time,the enrichment of AgNPs in aquatic organisms in the mode of multiple low-concentration AgNPs addition was 45.3% ~ 79.4% of that in the mode of single high-concentration addition.(4)AgNPs were mainly stored in the surface of the wall of pond microcosmos,sediment,and plants and animals.The most amount was stored in the upper sediment(0 ~ 5 cm),accounting for 41.35±15.82% of the total amount of silver nanoparticles added.(5)There was no significant difference in the number of phytoplankton species between the control group and the AgNPs-adding pond microcosm.The number of plankton declined slightly and then stabilized.