| Polycyclic Aromatic Hydrocarbons(PAHs)are a class of persistent organic pollutants with carcinogenic,teratogenic and mutagenic effects.PAHs in freshwater are increasingly polluting.The toxicity of PAHs to aquatic organisms has become a hot issue.Benzo(a)pyrene is a kind of pentacyclic polycyclic aromatic hydrocarbon persistent organic pollutants with strong carcinogenicity.In this paper,the toxic effects of benzo(a)pyrene on the important economic fish species-Crucian carp in China were explored by laboratory experiment.The acute toxicity of benzo(a)pyrene to Crucian carp was explored,superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),malondialdehyde(MDA),reduced glutathione(GSH)and nervous system acetylcholinesterase(AChE)under the stress of benzo(a)pyrene and the effect on the structure of gills and liver.The results are as follows:1.Acute toxicity test showed that: benzo(a)pyrene on the Crucian carp 96 h LC50 was1.472mg/L.According to the acute toxicity classification criteria,benzo(a)pyrene belongs to highly toxic substances.2.The effects of different concentrations of benzo(a)pyrene on the antioxidant defense system of liver,kidney,heart,gill,muscle and gonadal tissues of Crucian carp were studied.The results showed that exposure to benzo(a)pyrene could lead to antioxidant nonenzymatic system(SOD,POD,CAT,GSH)content changes,and changes in line with the "low and high inhibition" phenomenon,indicating the occurrence of oxidative stress;the content of MDA in lipid peroxidation increased with the increase of exposure concentration,indicating that lipid peroxidation and membrane system injury were observed.The activity of AChE in brain tissue decreased with the increase of exposure concentration,which indicated that the brain tissue was damaged.3.The results showed that the structure of gills and liver tissues changed significantly under200?g/L benzo(a)pyrene 25 days,indicating that the tissue damage of Crucian carp was caused by prolonged exposure to low concentration. |
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