Studies On The Enrichment And Hormone Interference Effects Of Propiconazole And Difenoconazole In Procypris Merus

Triazole fungicides belong to the largest variety of fungicides in the world,and they are one of the most commonly used pesticides in recent years.Since entering the pesticide market in the 1970s,many triazole fungicides such as tebuconazole,diniconazole,nitrile,difenoconazole,propiconazole and so on have been used in agricultural production.As triazole fungicides are widely used in agricultural production,their residues in the natural environment increase year by year,thus the potential toxicity risk to environmental organisms increases synchronously.Among them,the toxicity risk of triazole fungicides in water environment has attracted more and more attention,but the current research in this area is very limited.In this paper,propiconazole and difenoconazole were used as research objects,and Procypris merus as experimental organisms.The environmental risks and toxic effects of propiconazole and difenoconazole on Procypris merus were systematically studied from the aspects of field residue,acute toxicity,bioaccumulation,oxidative stress and thyroid hormone regulation.It provides theoretical guidance for further systematic assessment of the potential toxicity risk of triazole fungicides in water environment.The main results are as follows:（1）in order to obtain the residual risk data in the water environment of farmland ecosystem caused by the use of propiconazole and difenoconazole in agricultural production,the paddy field residue experiment under good agricultural production standard GAP was carried out according to its label information.In the experiment,five plots and a pond were designed and applied in the field according to the recommended dosage.during the experimental period,seven samples were carried out to detect the residual concentrations and dynamic changes of propiconazole and difenoconazole in water.The residual risk of water body after field application was evaluated.The results showed that the field concentration of propiconazole was 0.09μg/L～12.11μg/L,and the concentration of difenoconazole was 0.01μg/L～6.86μg/L.（2）the acute toxicity of propiconazole and difenoconazole to adult Carp was studied by semi-static test.The results showed that the 96h-LC₅₀ values of propiconazole and difenoconazole to Procypris merus were 11.3mg/L and31.2mg/L,respectively,indicating that the toxicity to Procypris merus was low,but the toxicity of propiconazole was higher than that of difenoconazole.（3）The LCMS/MS trace detection method for five kinds of tissues（meat,Gill,liver,intestine and kidney）in Procypris merus was successfully developed,and the enrichment behaviors of propiconazole and difenoconazole in five kinds of tissues were studied.The results showed that the bioconcentration coefficients of propiconazole and difenoconazole in Procypris merus were 0.66 and 27.08respectively,and those of difenoconazole in Procypris merus were 2.43 and 22.72,which were moderately concentrated pesticides.The bioconcentration coefficient decreased with the increase of exposure concentration.（4）The effects of propiconazole and difenoconazole on the activities of oxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）in fish were investigated by setting high and low concentration groups,and the effects of two environmental hormones on oxidative stress in fish were studied,among which the activities of three antioxidant enzymes in visceral tissue changed most significantly.In the 0.113 mg/L propiconazole 144h treatment group,the SOD activity decreased by 28.2%,the POD activity decreased by 30.2%,and the CAT activity decreased by 7.0%compared with the control group.In the 1.13 mg/L propiconazole 144h treatment group,the SOD activity,POD activity and CAT activity decreased by 56.9%,54.9%and 29.2%respectively compared with the control group.In 0.312 mg/L difenoconazole 144 h treatment group,SOD activity decreased 18.8%,POD activity decreased 37.2%,CAT activity increased 6.2%,compared with control group,SOD activity decreased 48.9%,POD activity decreased 43.5%,CAT activity decreased 14.8%compared with control group.The results showed that both fungicides could induce oxidative stress in three tissues（meat,viscera and Gill）of Procypris merus,and the activities of three antioxidant enzymes showed a significant dose-effect relationship with the prolongation of exposure time of the two fungicides.Propiconazole and difenoconazole significantly inhibited SOD and POD,while propiconazole and difenoconazole significantly induced CAT activity in Gill tissues of Procypris merus.（5）After stressed with 1.13 mg/L propiconazole and 3.12 mg/L difenoconazole in three parts of meat,viscera and Gill of grass carp,the content of thyrogen（T₃）in propiconazole group increased by 229.3%,219.9%and 167.0%respectively compared with the control group.T₃ content in difenoconazole group increased by 488.1%,408.1%and 395.2%respectively compared with the control group.Compared with the control group,the content of T₃ in the binary mixed treatment group increased by 652.0%,490.8%and 106.2%,respectively.Compared with the control group,the content of thyroxine（T₄）in propiconazole group decreased by 7.2%,and there was no significant change in viscera and Gill tissue.T₄ content in difenoconazole group decreased by 13.0%,20.7%and 18.9%respectively compared with the control group.Compared with the control group,the content of T₄ in the binary mixed treatment group decreased by 39%,but there was no significant change in viscera and Gill tissue.The results showed that the two fungicides had obvious hormonal effects in Procypris merus,and difenoconazole had a more significant effect on the contents of T₃and T₄ than propiconazole.Among the three monitored tissues,the change of thyroid hormone content in fish tissue was more significant than that in other tissues,and the change of T₃ and T₄ content in combined exposure group was more obvious than that in single pesticide treatment group.The content of T₃ in meat tissue of Procypris merus increased significantly with time,while the content of T₄decreased significantly with time,and the rising trend of T₃ was more obvious than that of T₄.The above results show that both propiconazole and difenoconazole can accumulate in carp and have different toxic effects on carp.This study will lay a research foundation for elucidating the potential risk of propiconazole and difenoconazole to aquatic ecosystem and provide an important theoretical basis for systematically evaluating the safety of aquatic organisms of the two fungicides.