The Biotoxic Effect Of ZnO Nanoparticles On Three Zooplankton

Zinc oxide nanoparticles is widely used in cosmetics,medical antibacterial,industrial coatings and other fields because of its special physical and chemical properties.It is directly or indirectly imported into the marine environment through industrial production,commodity used,air sedimentation,transport leakage,surface runoff,posing a potential threat to marine ecosystems.The zooplankton in the oceans influence or control primary productivity through ingestion,while the dynamics of their populations also affect the biomass of many fish and other animal resource.It is very important to study the toxic effects of ZnO-NPs on zooplankton because of its function that helping to understand the behavior of nanomaterials in water,evaluate the response of zooplankton to nanomaterials and realize the reasonable assessment of the environmental hazards of nanomaterials.In this study,we choosed three typical zooplankton species,including Tigriopus japonicus,Pseudodiaptomus annandai and Moina monogolica.Three zooplankton were mixed culture to analyse the toxic effects of ZnO-NPs on the survival,growth and reproduction of zooplankton.The aim is to evaluate the sensitivity of the three organisms to ZnO-NPs and to provide basic data for the toxicologists studies of nanomaterials in the sea area.The main results of this paper are as follows:1.Aggregates of 100 mg/L ZnO-NPs in pure water were flocculated from the original average particle size of 47.13 ± 11.08 nm to 213.90 ± 49.04 nm by scanning electron microscopy and transmission electron microscopy.2.In the acute toxicity experiment,the LC50 values of nauplius of T.japonicus,P.annandalei and M.mongolica were 1.37 mg/L,0.22 mg/L,1.90 mg/L,and 48h-LC50 of adult were 3.84 mg/L,1.04 mg/L,2.03 mg/L,respectively.3.In the low-dose long-term exposure toxicity experiment,for T.japonicus,the body length was delayed and death occurred in the N6-C1 stage.The larvae metamorphosis rate and adult development rate were 79.34%and 24.88%,respectively,compared with the control 97.25%and 78.60%were significantly different(p<0.05).The intrinsic rate of increase decreased to 0.19,the control group was 0.24.For P.annandalei,the body length was delayed and the death occurred in the N2-N3 stage.Although the larvae metamorphic rate was not affected,the adult development rate decreased and the control group was 94.87%(p<0.01),and reproductive inhibition occurs.For M.mongolica,the mortality rate was not higher than that of the control group,but the fecundity was significantly decreased.The developmental stage and the second reproductive interval were prolonged,so that the intrinsic rate of growth in the 0.25 mg/L concentration group decreased to 0.19,the control group was 0.29.4.1n the simulating lab experiment,the development of the three zooplankton was delayed by ZnO-NPs.There was no significant change in the number of populations of T.japonicus in the experimental period.There were significant difference of the population of P.annandalei between the 0.2 mg/L group and control,mainly due to the difference of pre-developmental retardation and reproductive grade.The populations of M.mongolica decreased after the 8th day because of the death the FO generation,but the number of populations was increased after the offspring hatching.