| P-tert-Butylphenol is a fine chemical intermediate,which is mainly used for the preparation of antioxidants and the production of oil-soluble phenolic resin,polycarbonate and other chemicals.It belongs to alkyl phenol endocrine disrupting substances.With the mass production and wide application of PTBP,it has been detected to varying degrees in a variety of environmental media.PTBP has endocrine interference and has certain bioaccumulation in the environment.It can accumulate in organisms through the food chain and then endanger human health.Cadmium(Cd)is one of the main inorganic pollutants in polluted soil,ranking first in heavy metal pollution.Cd is highly toxic and difficult to degrade.It is easy to accumulate and metabolize slowly in organisms,which is harmful to organisms.At present,phenols and Cd have been widely detected in soil,and both of them have high persistence,studies have shown that the presence of phenols will strengthen the adsorption capacity of soil for Cd.Therefore,PTBP and Cd were selected as the objects of the combined pollution of organic matter and heavy metals in this experiment to explore the eco-toxic effects of PTBP alone and combined with Cd in soil environment.Eisenia foetida was used as the test organism in this experiment,and was poisoned in artificial soil for 28 days.Five concentrations of 0,2.5,5,10 and 15 mg·kg-1were set for PTBP,and combined with 2 mg·kg-1Cd respectively.Samples were taken at the 7th,14th,21st and 28th day of exposure.The measured indexes were the activity of antioxidant enzymes(SOD,CAT,POD),the activity of GST,the content of ROS,the content of MDA and DNA damage of earthworm coelom cells.The main results of this experiment are as follows:(1)When exposed to PTBP alone,the activity of antioxidant enzymes(SOD,CAT,POD)decreased first and then increased,while the activity of GST was inhibited all the time.The content of MDA in earthworms increased as a whole,and the content of ROS showed a trend of decrease-increase-decrease.The content of ROS was slightly lower than that of the control group in the later stage of exposure,indicating that PTBP caused certain oxidative damage to earthworm with the increase of stress time,but the organism also had the corresponding self-healing ability.(2)When exposed to PTBP alone,the DNA of coelomic cells of earthworm was damaged to different degrees in the treatment groups with different concentrations,and the degree of damage was positively correlated with the concentration and time of exposure.(3)When exposed to PTBP-Cd combined pollution,the activity of antioxidant enzymes in low concentration compound group(2.5+2,5+2 mg·kg-1)was similar to that in single exposure,while high concentration compound group(10+2,15+2 mg·kg-1)strengthened the oxidative stress on earthworms to a certain extent;Meanwhile,the inhibition of the activity of GST was higher than that of PTBP alone.The content of ROS and MDA decreased in the later stage of exposure,indicating that the combination of PTBP and Cd showed antagonistic effect to a certain extent and weakened the damage of lipid peroxidation on earthworms.(4)When exposed to PTBP-Cd combined pollution,the variation trend of DNA damage degree of earthworm in compound group was similar to that in PTBP single group but always higher than that in PTBP single group,and the damage degree changed more significantly with the increase of exposure time.The combination of PTBP and Cd showed synergistic effect to a certain extent. |
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