Study On The Pollution Characteristics And Vertical Migration Mechanism Of Antibiotics In Soil Of Livestock And Poultry Breeding Areas

In recent years,the environmental pollution caused by a large number of veterinary antibiotics used in livestock and poultry breeding has attracted worldwide attention.In this study,7 livestock farms in Tongshan District,Xuzhou City were taken as the investigation objects.By collecting the surrounding soil of each farm,34kinds of antibiotics of five categories were selected for testing and analysis,and then the distribution and pollution characteristics of antibiotics in the surrounding soil of livestock and poultry farms in Xuzhou City were elaborated.Then,the adsorption characteristics and vertical migration of the macrolide antibiotics（MAs）,which had the highest pollution level,were studied.The following conclusions were drawn:（1）The average detection rates of five antibiotics in soil samples around seven farms were as follows:quinolones（96.4%）>nitroimidazoles（85.7%）>macrolides（82.1%）>sulfonamides（64.8%）>β-lactams（61.9%）,the average detected content is as follows:macrolides(5.55μg·kg^-1)>quinolones(3.72μg·kg^-1)>nitroimidazoles(1.78μg·kg^-1)>sulfonamides(0.75μg·kg^-1)>β-lactams(0.50μg·kg^-1),the average contents of all antibiotics in the surrounding soil were as follows:horse soil(8.08μg·kg^-1)>goose soil(2.58μg·kg^-1)>chicken soil(1.82μg·kg^-1)>duck soil(1.62μg·kg^-1)>cow soil(1.39μg·kg^-1)>sheep soil(1.19μg·kg^-1)>pig soil(0.47μg·kg^-1).Therefore,macrolide and quinolones antibiotics are the most serious antibiotics in the soil pollution of livestock and poultry breeding areas in Tongshan District,Xuzhou City,and the soil antibiotic pollution is the most serious near horse and goose farms.（2）The adsorption kinetic tests showed that the adsorption equilibrium state was reached at the 16th hour,and the Elovich equation could better fit the dynamic adsorption process of JOS in the soil.Isothermal adsorption tests show that Freundlich model has a better fitting effect on the isothermal adsorption process of JOS in the soil,and the lower the temperature,the stronger the adsorption capacity.This adsorption process is spontaneous physical adsorption.The orthogonal experiment showed that the adsorption capacity was the strongest when the p H of soil solution was 7.5.Increasing the initial concentration of antibiotics promoted JOS adsorption in soil.The inhibition effect of Ca²⁺on soil JOS adsorption was stronger than that of Na⁺,while Fe³⁺had an obvious promotion effect on soil JOS adsorption test.（3）Leaching test of soil column showed that the vertical migration ability of JOS in soil column was enhanced with the increase of application amount.The neutral leaching solution had little effect on the soil column test results,and the alkaline environment was more conducive to the downward migration of antibiotics than the neutral environment.Fe³⁺significantly inhibited the vertical migration of JOS in the soil column,while Ca²⁺significantly promoted the vertical migration of JOS in soil columns,while Na⁺had little effect on the vertical migration of JOS in soil columns.There are 30 figures,20 tables and 114 references in this paper.