Ecological Toxic Effects Of Chlorobenzene, M-cresol And Urban Sewage On Zebrafish Embryos And Larvas

The increasing of number and variety of poisonous and harmful pollutants in environment posed a great threat to ecological environment. How to evaluate the influence of these pollutants to creatures aroused more and more attention recently. By consulting a large number of documents at home and abroad, we analyzed briefly the ecological toxicity study progress of chlorobenzene, m-cresol and urban sewage. Compared with other many pollutants, they had higher toxicity, but lack of relevant toxicity data of embryos and larvas of fish. As toxicity assessment, the embryos and larvas of zebrafish have advantages such as convenience, sensitiveness, economy, and good correlation with many other toxicity data. Therefore, this paper used developmental technology of zebrafish embryos and static experiment method, selected three kinds of pollutants mentioned above, tested their single toxicity and joint toxicity of part pollutants, analysed quantificationally the determination results, and established parameters regression equations of lethal effects of single pollutant to zebrafish larvas.Acute toxicity tests were conducted to embryos and larvas of zebrafish. And then, researched the toxic effects, including lethal effects and sublethal effects of chlorobenzene, m-cresol and urban sewage to embryos and fries. The dose-effect and time-effect relationships between each toxicology endpoint for corresponding effect and exposure concentration of pollutants were studied, too. This provided scientific basis for further research on choice of dosage, time and toxicology endpoint in aquatic organisms ecotoxicological study. Meanwhile, toxigenicity mechanisms were revealed preliminarily for chlorobenzene, m-cresol and urban sewage. Especially research results were showed below:(1) Zebrafish embryos were exposed to chlorobenzene, m-cresol and urban sewage of different concentrations respectively, whether single or joint toxicity tests, they both had different toxicology endpionts in different time, for chlorobenzene embryonic toxicity were mainly 48h edema, m-cresol influenced primarily on melanin and uranidin, and urban sewage acted on melanin, eyespots 20s active movement at 24h and blood circulation, etc. In addition, at the same time, pollutants of different concentrations on embryonic toxicity had also greatly distinction.(2) In toxic exposure experiments of chlorobenzene, m-cresol and urban sewage, except for the lowest concentration groups, other various concentrations groups caused different death rates of zebrafish larvas. Their parameters regression equations were different, showed difference in toxigenicity mechanisms.(3) Via joint action experiments of chlorobenzene and m-cresol, toxicities to zebrafish embryos and larvas were evaluated by additive index method, toxic unit graphic method and toxicity units analytical method. The results indicated that it had different effect types in different time and different concentrations, such as antagonistic joint action, sometimes for additional joint action or some synergistic joint action. So, their joint mechanisms were very complex.(4) Choosing different exposure time in experiment, the experimental results had prodigious difference. Experiments showed that the earlier zebrsfish embryos and larvas were exposured, the more sensitive they would be to toxicity of pollutants.