| In recent years, oil spill accidents occur frequently, causing a great deal of serious pollution. As one of main measures of handling oil spill, dispersants are widely used. In this paper, a model organism Hemicentrotus Pulcherrimus was selected as test organism. The toxicity effects of fuel oil treated by dispersant on sea urchins were studied by detecting different level indicators (individual development, biochemical reactions and molecular genetics). The main conclusions of the study were as follows.(1) The emulsion efficiency of dispersants on fuel oil was studied. The results showed that:under the same ratio of oil and water, the concentration of oil in emulsion increased1.2times. The properties of oil, temperature and salinity of the water will affect the oil concentration of emulsion. It is confirmed that conventional type dispersants optimum mixing ratio was the20%amount of oil spill.(2) The acute toxic effects of dispersions and emulsion of120#fuel oil on the sea urchin embryos were studied. The results showed that:The EC50values of dispersions of fuel oil for the sea urchin embryo two cells, four cells, eight-cell and blastocyst were0.394g/L,0.254g/L,0.106g/L and0.0333g/L respectively; The EC50values of emulsion were0.205g/L,0.106g/L,0.085g/L and0.00527g/L respectively. Results of embryo experiments illustrated that toxicity of emulsion of120#fuel oil increased0.92,1.4,0.3and5.3times, respectively, than dispersion on different developmental stages of sea urchin embryo. Blastocyst stage toxicity was most obvious related with increasing accumulation of petroleum hydrocarbons.(3) The effects of dispersions and emulsion of fuel oil on the sea urchin antioxidant system was detected. The results showed that:enzyme activities of sea urchin in different tissues were significantly different. Four enzymes (CAT, SOD, GST and GPx) activities in gonads and intestines of sea urchin were inhibited after induced in dispersions and emulsion of fuel oil, however, enzymes activities in emulsion were significantly higher than in dispersion. Meanwhile maximum inductions of multiples of three kinds of enzyme activities (SOD, GST and GPx) of intestine were significantly higher than gonads; CAT and GST enzymes of sea urchin intestines were more sensitive to oil pollution than SOD and GPx enzymes. Conclusion:Toxicity effects of emulsion of fuel oil on sea urchin tissue enzyme activities were greater than dispersion. CAT and GST enzyme of sea urchins intestinal was more suitable as biomarkers to monitor marine petroleum hydrocarbon pollution.(4) The chronic DNA damage of dispersions and emulsion of fuel oil on sea urchin tissue were studied by using SCGE. The results showed that:Gonadal cells had no DNA damage in dispersions, emulsion and control group, and DNA damage of intestinal cells showed significant positive growth with the concentration and exposure time. DNA damage of intestinal cells was significantly higher in emulsion than in dispersion. It indicated that the use of dispersants increased DNA damage of the fuel oil on the sea urchin tissue cell.(5) From the molecular level, complement CyⅡa and SP-runt gene mutation was detected through PCR-SSCP technique and sequence determination. The results showed that CyⅡa gene related to the development of sea urchins did not mutation in all experimental groups. However, SP-runt gene had appeared33.33%mutation in two high concentration groups (2.25and4.5g/L) by exposure21d. The globle genomic methylation was detected by high performance liquid chromatography (HPLC). The results showed that with exposure time extension and increasing concentration, methylation levels were inhibited in dispersion and emulsion, and lower methylation levels appeared in emulsion. It showed that genotoxicity of processed fuel oil by dispersants on the sea urchin was greater than dispersion.(6) Bioconcentration of petroleum hydrocarbons in the sea urchin tissues were measured in dispersions and emulsions of fuel oil by gas mass spectrometry. The results suggested that different PAHs bioaccumulation factors were clear distinction between the degrees of change, and bioaccumulation factors decreased with increasing concentration of dispersions and emulsions. Concentration increasing multiples of5-6ring PAHs of emulsion was higher than the2-4ring, however, concentration of5-6ring PAHs in vivo of sea urchin of emulsion compared dispersion was no significant changes. Bioaccumulation factor of2-4ring PAHs of nine major in emulsion (naphthalene,2-methyl naphthalene,1-methyl naphthalene, phenanthrene and pyrene) was significantly higher than5ring PAHs (benzo fluoranthene, pyrene and benzopyrene).It indicated that dispersant increased bioaccumulation2-4ring PAHs of emulsion of fuel oil.Application of dispersants lead to the toxicity effects of fuel oil on sea urchin development, tissue and genetic. |
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