Comparative Study On The Toxicity Of Different Dispersants To The Early Development Of Marine Medaka(Oryzias Melatigma)

Chemical dispersants are frequently used in oil spill to deal with oil contamination onsurface water, and to avoid its potential impact on coastline and organisms after entry intodeep water. However, it was reported that chemical dispersants can enhanced acute toxicity ofcrude oil significantly, while few study has reported the impact of biological dispersants by Inoil spill accident of Dalian “7.16”,relevant departments used a large amount of chemical andbiological dispersants to eliminate oil pollution on surface seawater. There is an arisingconcern in regards to the ways of two dispersants to influence crude oil toxicity and theirpotential long-term environmental effects, which should be properly assessed. far.Given thecircumstance, early-life stages of marine medaka (Oryzias melastigma) was selected as testingorganism in this study to investigate the effects of crude oil and chemical/biologicaldispersants used in Dalian oil spill on the development of fish. Experimental results areexpected to provide theoretical reference for biological toxicity assessment of oil spill andformulation of management strategy of rational use of dispersants. The main experimentalresults are as follows:1. The addition of both chemical and biological dispersants increased the abnormal rate,BSD index, mortality and retarded hatching time and hatching rate of marine medakaembryos.2. There was a significant difference of CYP1A induction by water-accommodatedfractions(WAF), enhanced water-accomodated fractions(CE-WAF)and biological enhancedwater-accommodated fractions(BE-WAF)in medaka embryos. CE-WAF andBE-WAFtreatments showed a trend of increase followed by a decrease with increasingexposure concentrations at11d.3. WAF, CE-WAF and BE-WAF can all induce DNA damage in medaka juveniles;however, there was a significant difference of DNA damage among the threechemicals-treated groups with the rank of CE-WAF>WAF>BE-WAF.4. Total petroleum hydrocarbon (THC) analysis result demonstrated that the rank ofTHC contents was BE-WAF>CE-WAF>WAF. Seventeen kinds of PAHs in above threechemicals were analyzed and the higher contents inside the three were naphthalene (Nap),phenanthrene (Phe), pyrene (Pyr), fluorine (Fl), acenaphthene (Acp) and acenaphthene(Ace).5. The toxicity of crude oil to medaka embryos significantly increased after the addition of dispersants. Based on the existing data, the rank of toxicities was as follows:CE-WAF>BE-WAF>WAF.