Research Of Joint Toxicity Of Triphenyl Phosphate And Cadmium To Earthworms

As one of the substitutes of brominated flame retardants,triphenyl phosphate has been widely used in a variety of applications,with its increasing production and use,TPHP has frequently been detected in various environmental substrates.Due to its high hydrophobicity,TPHP can easily accumulate in soil,so it has become one of the common pollutants in soil.Cadmium is one of the common heavy metals in soil,and it is also the main heavy metal element that causes soil pollution in my country.TPHP and Cd,as two substances that can adversely affect the environment,both exist in the soil environment,however,little is known about the ecotoxicity effects of TPHP single and in combination with Cd.Earthworms are an important part of the soil ecosystem and play an important role in the turnover of soil organic matter,and are often used to study toxicity of anthropogenic chemicals present in soil.Therefore,it is of great significance to study the effects of TPHP single and Cd combined with TPHP on earthworms,which will help to evaluate the environmental risks of TPHP and its combination with Cd on soil ecosystem.In this paper,the effects of TPHP single and Cd combined with TPHP on oxidative stress and DNA damage were studied by using artificial soil method.The reactive oxygen species(ROS)content,superoxide dismutase(SOD)activity,catalase(CAT)activity,peroxidase(POD)activity,glutathione S-transferase(GST)activity,malondialdehyde(MDA)content and the degree of DNA damage in earthworms(Eisenia fetida)were measured after exposure to 0,20,40,60,and 80 mg·kg^-1 TPHP and each concentration of TPHP combined with 5 mg·kg^-1 Cd for7,14,21,and 28 days.The results of this research are as follows:(1)When exposed to TPHP,the ROS content in earthworms increased significantly,showing an obvious accumulation trend,and the oxidative balance in the body was broken.The activities of antioxidant enzymes(SOD,CAT,POD)and detoxification enzyme GST showed a trend of first activation and then inhibition with the prolongation of exposure time.MDA content was also significantly increased,resulting in lipid peroxidation.(2)When exposed to TPHP,the OTM values of all treatment concentrations were significantly higher than those of the control group,and increased with the increase of exposure concentration and exposure time,indicating that TPHP has a potential genotoxic threat to earthworms.(3)When TPHP and Cd combined exposure,the content of ROS was significantly increased,and the activity of antioxidant enzymes(SOD,CAT and POD)were activated in the early stage of the experiment and inhibited in the later stage of the experiment.The detoxification enzyme GST activity was inhibited throughout the experimental period.Antioxidative defense system and detoxification response were not able to protect earthworms from oxidative damage caused by the complexation of TPHP and Cd,so the MDA content was significantly increased,resulting in higher lipid peroxidation levels.Compound exposure produced greater oxidative stress and resulted in more severe oxidative damage than TPHP single exposure.(4)When TPHP and Cd combined exposure,the change of earthworms OTM value was similar to that of TPHP single exposure,and the DNA damage of earthworm coelomocytes was more serious when combined exposure.Cd aggravated the DNA damage of earthworm coelomocytes by TPHP.