Toxicity Effects And Mechanism Of Dispersant And Fuel Oil On The Embryo Of Marine Medaka

This study simulated the toxic effects of water-accommodated fractions(WAFs)and chemical enhanced water-accommodated fractions(CE-WAFs)of 120#fuel oil on marine model organism marine medaka(Oryzias melastigma)embryos under the conditions of laboratory,comparing the different toxicity of the different exposure solutions.This paper discussed the influence of dispersants on oil pollution effects from various angles,and provided reliable basis for correct and rational use of dispersants.In addition,the toxicity effects of petroleum hydrocarbons pollution on organisms were comprehensively analyzed,which provided basic data for quantitative and accurate evaluation for the damage caused by oil pollution to marine ecological environment,and provided a reference way for the study of bio-toxicity of petroleum hydrocarbons pollution in China.The time-dose-effect relationship was established by detecting the content of polycyclic aromatic hydrocarbons(PAHs)in the dispersions.At the same time,the accumulation of PAHs in embryos and bioaccumulation kinetics were studied to explore the toxicological mechanism of petroleum hydrocarbons on marine medaka embryos,so as to further analyze the mechanism of amplification effect of oil spill dispersants on petroleum toxicity.The main conclusions are as follows:(1)The addition of dispersant had a significant effect on the increase of total petroleum hydrocarbons(TPH)content and the decrease of oil droplet size.The solubilization ability of GM-2 was significant.Dispersants not only promoted the dissolution of PAHs in water,but also affected the relative abundance of high and low molecular weight PAHs,parent PAHs(pPAHs)and alkyl-PAHs(aPAHs).(2)Exposure to petroleum dispersions caused a series of developmental problems on embyros,such as developmental abnormality,the increase in mortality,hatching abnormality and developmental delay.The toxicity of different dispersions was CE-WAFs>WAFs.However,there was no significant change in embryo weight,suggesting that exposure to dispersions did not affect the fetal uptake of substances from the outside.(3)Exposure to petroleum dispersions affected the antioxidant system of embryos.Exposure to petroleum dispersions could induce and inhibit oxidative stress on marine medaka embryos,resulting in significant changes in the activities of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GPx).The order of antioxidant enzymes in exposure solutions was CE-WAFs>WAFs.During exposure,the relative induction rate of GPx was the largest and the change amplitude was the most obvious.(4)Exposure to petroleum dispersions could cause DNA damage to marine medaka embryos,and the order of DNA damage degree was CE-WAFs>WAFs.The DNA content of WAFs experimental group was affected by the DNA repair ability of embryos in the middle and late period of exposure,and there was no obvious concentration-effect relationship.CE-WAFs induced high genotoxicity,and cells have been unable to repair their DNA by themselves,making DNA damage in cells continue to deteriorate.(5)Both phase I enzyme EROD and phase II enzyme GST of marine medaka embryos were induced first and then inhibited under the stress of petroleum dispersion.As phase I enzyme,the change of EROD is more obvious,and it can respond to the pollution stress of PAHs more accurately and timely.The changes of EROD and GST in the CE-WAFs group were greater during the exposure period.(6)Through the determination of PAHs content in embryos,it was found that the accumulative content of PAHs in embryos showed dose-effect and time-effect,and the content relationship was CE-WAFs>WAFs;the content of low molecular weight PAHs was higher,and gradually decreased as the prolongation of exposure time.The analysis of embryonic enrichment kinetics showed that the absorption rate constant kt and the bioaccumulation coefficient BCF of PAHs were positively correlated with the exposure concentration,which accorded with the relationship:CE-WAFs>WAFs;the equilibrium concentration of CAmax and the half-life B 1/2 of pollutants were positively correlated with the exposure concentration,and CE-WAFs>WAFs;in WAFs group,embryos had strong enrichment effect on low molecular weight PAHs,the addition of GM-2 dispersant induced a strong bioaccumulation coefficient on high molecular weight PAHs and all aPAHs to embryos;and the BCF of PAHs was higher than that of corresponding pPAHs,and its rule is CE-WAFs>WAFs.