Joint Toxic Effects Of Polystyrene Microplastics And Polybrominated Diphenyl Ethers On Chlamys Farreri

Marine microplastics pollution has become a global environmental problem.Microplastics have the characteristics of small particles,hydrophobicity and so on.They can be used as carriers of persistent organic pollutants,metal elements and other toxic and harmful substances.Polybrominated diphenyl ethers(PBDEs)are the persistent organic pollutants(POPs)in the marine environment,whic has serious impacts on the marine environment and marine organism.Chlamys farreris is marine filter-feeding bivalves,which plays an important role in the material cycle and energy flow in marine ecosystem.At present,there are few studies on the joint toxicity of microplastics and PBDEs,and its mechanism is not clear.In this study,the content of microplastic and PBDEs in the fish of the South China Sea was measured,and the correlation between microplastic and PBDEs was analyzed.The effect of MPs on the enrichment and purification of Decabromodiphenyl ether(BDE-209)in Chlamys farreris was analyzed by using MPs and BDE-209 as experimental materials.Finally,The combined toxic effect of MPs and BDE-209 on Chlamys farreris was studied at the cell level and histopathology.The contents and main conclusions of the study are as follows:1.The content of microplastics and PBDEs in Fish at South China Sea.The contents of microplastics and PBDEs in ten species of fish at the South China Sea were determined,and the correlation between them was analyzed.The results show that :(1)Microplastics were detected in ten species of fish.The range of microplastics content is 0.27~4.15 items/g.The mainly particle size of microplastics is < 0.5mm,the mainly color is transparent,the mainly shape are thin film and fibrous,and the content of spherical microplastics is less.(2)PBDEs were detected in ten species of fish,of which the BDE-99,BDE-100,and BDE-183 are the main homologues,and the ability of fish liver to enrich PBDEs is higher than that of muscle.(3)There was a significant positive correlation between the contents of PBDEs and microplastics in fish organisms.It is s?ggested that PBDEs can be adsorbed on the microplastics forming complex to enter the organism,thus increasing the concentration of PBDEs in organism.2.The effect of MPs on the enrichment of BDE-209 in Chlamys farreris.Chlamys farreri was divided into control group,low BDE-209 group,low BDE-209 group,high BDE-209 group,MPs Low BDE-209 group and MPs High BDE-209 group for exposure and purification experiment.The effect of polystyrene on the enrichment of BDE-209 in chlamys farreri was studied.The results show that :(1)In the exposure experiment,the BDE-209 content of chlamys farreri in all exposed groups was higher than that in the control group.In high concentration group,the BDE-209 content of chlamys farreri which was exposed to BDE-209 and MPs was significantly higher than that was exposed to BDE-209 alone(p < 0.05).This may be due to that the BDE-209 was absorbed into chlamys farreri by adsorbed on the surface of MPs,then the BDE-209 was desorbed to increase the bioconcentration of BDE-209 in chlamys farreri.(2)In the purification experiment,the BDE-209 content of chlamys farreri which was exposed to BDE-209 and PS was significantly lower than that was exposed to BDE-209 alone(p < 0.05).This may be due to that MPs adsorbed BDE-209 from chlamys farreri after MPs enterring chlamys farreri,then the MPs and BDE-209 were discharged which promoted the purification of BDE-209 in chlamys farreri.(3)In the presence of MPs,chlamys farreri has higher absorptivity constant and clearance constant to BDE-209.The results showed that MPs could promote the enrichment of BDE-209 and decrease the half-life and residence time of BDE-209 in chlamys farreri.3.The combined toxic effect of MPs and BDE-209 on Chlamys farreris.Chlamys farreri was divided into control group,low BDE-209 group,low BDE-209 group,high BDE-209 group,PS Low BDE-209 group and PS High BDE-209 group for15 day exposure experiment.The cell death rate,phagocytic rate,DNA damage and histopathology of chlamys farreri were analyzed by flow cytometer detection and comet assay.The results showed that:(1)The cell death rate of chlamys farreri in all experimental groups except MPs group was significantly higher than that in control group(p < 0.05).In high concentration group,the cell death rate of chlamys farreri which was exposed to BDE-209 and MPs was significantly higher than that was exposed to BDE-209 alone(p < 0.05).This indicated that BDE-209 increased the cell death rate of chlamys farreri,and MPs enhanced the biotoxicity of BDE-209 to chlamys farreri.(2)The phagocytic rate of chlamys farreri cells in each experimental group was significantly lower than that in the control group(P < 0.05),and the phagocytic rate of chlamys farreri cells which was exposed to BDE-209 and MPs was significantly lower than that was exposed to BDE-209 alone(p < 0.05).This s?ggests that BDE-209 can damage the immune system of schlamys farreri,and MPs can enhance the immune damage of BDE-209 to chlamys farreri.(3)The DNA tail of the Chlamys farreri cell which was exposed to BDE-209 alone and exposed to BDE-209 and MPs was increase.In high concentration group,the DNA tail of Chlamys farreri cell which was exposed to BDE-209 and MPs was significantly higher than that was exposed to BDE-209 alone(p < 0.05).This s?ggests that BDE-209 may cause DNA damage to chlamys farreri cells,and MPs could enhance the DNA damage which lead to genotoxicity.(4)High concentration of BDE-209 had a certain effect on the Gill cells of Chlamys farreri,and the presence of MPs could increase the damage of BDE-209.MPs and high concentration of BDE-209 had toxic effects on the digestive gland cells of chlamys farreri.And under the condition of low concentration or high concentration of BDE-209,the presence of MPs did not significantly enhance the effect of BDE-209 on the digestive gland cells of Chlamys farreri.