| With the development of offshore oil exploration,transportation and storage,oil spills in coastal areas have become more and more serious,which inevitably causes environmental pollution in the intertidal zone.Crude oil is a complex hydrocarbon compound,which is insoluble in water and volatilizes in a small amount.Among them,polycyclic aromatic hydrocarbons are carcinogenic,teratogenic,highly toxic and persistent,therefore extremely harmful to the environment and human health.In this study,the muddy intertidal zone and Periophthalmus modestus were selected as the research objects to carry out indoor simulation experiments.The P.modestus was exposed to crude oil contaminated sediments at concentrations of 0mg/kg,500mg/kg,1000mg/kgand 1500mg/kg,and then samples were taken in exposure time of1,3,6,9,12,15 days.At last recovery tests were carried out for 6 days.The activities changes of superoxide dismutase(SOD),catalase(CAT),glutathione peroxidase(GPx)and glutathione s-transferase(GST)in the gills,liver and muscle of P.modestus were investigated,and the toxic effects of crude oil pollution on intertidal organisms were evaluated by using the IBR index.Combined with the physical index of resistivity,the relationships between the resistivity and biomarkers were analyzed,and the feasibility of resistivity as a biological assessment tool of intertidal oil pollution was discussed to provide a theoretical basis for the protection of marine resources.The conclusions are as follows.1.The research results of the effect of crude oil on the antioxidant enzyme activities of mudskippers showed that the enzyme activities of various tissues in P.modestus were similar after exposure to crude oil and the overall trend was firstly increase and then decrease.Among them,SOD activation first appeared in muscle,CAT,GPx and GST were all in gills,which may be related to the lack of detoxification function of gills and muscle.After decontamination,there was no significant difference between the experimental groups and the control groups in different tissues,indicating that the influence of crude oil concentrations in the experiment on the tissues of P.modestus was basically within the adjustable range of the organism.It was found in the experiment that the activity of single antioxidant enzyme was affected by many factors,it was not suitable to be used as a separate biomarker of petroleum pollution and should be considered in combination with several enzymes.2.IBR analysis showed that different concentrations of pollution had different responses to IBR in different tissues of P.modestus.Under the same exposure time,the IBR value in gills increased with the increase of crude oil concentration,that was,when the crude oil concentration was 1500mg/kg,the gills caused the most damage,but there was no obvious rule in liver and muscle.In the crude oil exposure stage,the IBR value in each tissue gradually increased with the increase of time,indicating that the damage of crude oil pollution to P.modestus mainly concentrated in the later period of the experiment.The IBR values in the recovery stage were reduced to the level of the control group,indicating that no irreversible damage was caused to the organism at this concentration,and that the sensitivity of gills to crude oil pollution at this concentration was higher than that of liver and muscle.3.The analysis of the relationship between resistivity and biomarkers showed that the variation trends of resistivity in sediments with different oil contents were similar,which firstly decreased and then increased with time.Resistivity was significantly negatively correlated with IBR in liver,SOD,CAT and GST in liver,CAT in gill and GST in muscle.Resistivity was more correlated with IBR and antioxidant enzyme activity in the liver than that of gills and muscles.So resistivity can be used as an index to directly monitor and evaluate the biological toxicity of oil pollution in intertidal zone. |
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