Study On The Combined Toxicity Of Polystyrene Microplastics And 3,6-dibromocarbazole On Zebrafish Embryos

Polyhalogenated Carbazoles(PHCZs),as a new type of organic pollutants,are widely detected in water,soil and air all over the world.However,there are few studies on the environmental and health risk assessment of PHCZs,and important data on bioenrichment and toxic effects are still scarce.PHCZs do not exist independently in the environment,but coexist with a variety of pollutants.Microplastics(MPs)have stable chemical properties,large specific surface area,strong hydrophobicity,and the ability to adsorb organic pollutants.They can persist in the environment for long periods of time and migrate with water flow and air movement,changing the bioavailability and toxicity of many pollutants and bringing uncertainty to ecological risk assessment.In order to clarify the interaction between MPs and PHCZs and their joint toxicity to organisms,3,6-dibromocarmazole(3,6-DBCZ)was used as representative PHCZs,polystyrene(PS,particle size 5 μm,50 μm)was used as representative MPs,and zebrafish embryos were used as subjects.The toxic effects of two pollutants on zebrafish embryo development and the effects of microplastic particle size on the enrichment of PHCZs in zebrafish embryo were investigated.The specific research contents included: the zebrafish embryos were exposed to concentrations of 0.5 mg/L 3,6-DBCZ and 10 mg/L PS(5 μm,50μm)with combined or independently.By observing the embryonic development process,the mortality rate,we detemined teratogenicity rate and hatching rate.By measuring the levels of oxidative stress,cell apoptosis and dioxin-like markers,the toxic effects and intrinsic mechanisms of the two pollutants in the embryonic development stage of zebrafish were identified.We determined the concentration of PHCZs in zebrafish larvae by using a triple quadrupole combined temperament analyzer,and determined the enrichment level of PHCZs in zebrafish larvae,revealed the influence of different particle size MPs on PHCZs enrichment in zebrafish larvae.The main results of this study are as follows:(1)In this study,3,6-DBCZ and PS-MPs had no significant effects on embryonic mortality and hatching rate of zebrafish under separate and mixed exposure,but could lead to a significant increase in the rate of deformities.(2)The mixed exposure of 3,6-DBCZ and PSMPs showed antagonistic effects on oxidative stress damage and apoptosis.(3)Both sizes of PS-MPs promoted the accumulation of 3,6-DBCZ in zebrafish larvae;The accumulation of3,6-DBCZ in zebrafish larvae was enhanced by larger particle size PS-MPs(50 μm),and significant dioxin-like toxicity was induced.In this study,the toxic effects of MPs and PHCZs on zebrafish embryo development and the effects of microplastics on PHCZs enrichment in zebrafish embryo were investigated,which provides strong scientific support for improving the ecological effects and risk assessment of new pollutants MPs and PHCZs,and has theoretical research value and practical significance.