| In recent years,due to the large use of veterinary antibiotics,the pollution of antibiotics and resistance genes（ARGs）in the livestock and poultry breeding industry has become very serious.Livestock and poultry manure has become an important reservoir of antibiotics and ARGs,and has caused potential ecological threats to the surrounding environment.Therefore,it is necessary to study the pollution characteristics of antibiotics and ARGs in the manure of different livestock and poultry farms and assess the ecological risks to the surrounding environment.In addition,most livestock and poultry farms have set up manure treatment process,but their effects on the removal of antibiotics and ARGs in manure are not clear.Therefore,this experiment mainly focused on the following research:systematically analyzing of distribution characteristics and pollution status of20 antibiotics（4 classes）and 13 kinds of ARGs（5 classes）in feces,sewage and soil in different farms（pig,chicken and cattle）;Investigating the overall removal effects of different treatment processes on antibiotics and ARGs in livestock and poultry manure;and comparing the removal effects of different treatment units on antibiotics and ARGs.The main conclusions are as follows:（1）Four classes of antibiotics were detected in the manure and the surrounding farmland soil of farms in Tianjin.The detection concentration of different types of antibiotics was:tetracyclines（22.77mg/kg）>quinolones（1.65 mg/kg）>sulfonamides（553.40μg/kg）>macrolides（268.09μg/kg）.The law of antibiotic residual concentration in different livestock and poultry manures was:pig feces（26.82 mg/kg）>chicken feces（3.04 mg/kg）>cattle feces（55.87μg/kg）.The residual concentration of antibiotics in pig farm wastewater（144.69μg/L）is higher than that in cattle farm（1.75μg/L）;There are differences in the antibiotic residues in the feces from different livestock and poultry growth stages:the residual concentrations of antibiotics in fat pig manure/piglet manure and adult cow manure were higher than in sow manure and calf manure respectively.The antibiotic contents in the soil were increased by 43 times,34 times and 30 times after the application of chicken manure,pig manure and cow manure,respectively.（2）Five classes of ARGs were common in the manure and surrounding farmland soils of farms in Tianjin.Except for the quinolones qnr S,qnr B,oqx B and erm C,the detection rates of the remaining ARGs were 100%,and the relative abundances were high(10-4～100).Overall,the relative abundances of ARGs on the manure of chicken farms were the highest,followed by those on pig farms,and the lowest were on cattle farms.The relative abundances of ARGs in pig farm wastewater were higher than that in cattle farms;The abundances of tet O in pig farm manure were highest,and the relative abundances of tet W,tet O and str A in cattle farm manure were the highest,being 10-3～10-1;and the relative abundances of tet O,erm B and str A in chicken farm manure were10-1～100.The ARGs in fattening pig manure,piglet manure and sow manure were not very different,and the relative abundances of ARGs in adult cow manure were higher than that of calf manure.After applying chicken manure,pig manure and cow manure,the relative abundances of ARGs in farmland soil were increased by 19 times,18 times and 11 times,respectively.（3）The treatment processes on those animal farms had good removal efficiencies of antibiotics in manure.For wastewater,the pig farm wastewater treatment process had good removal effects on 9 antibiotics such as OTC,TIL,CTC and DXC,and the removal efficiencies were 33.63%～100%.Among treatment units,the anaerobic fermentation had a better removal effect on antibiotics.The cattle farm wastewater treatment process had good removal effects on 3antibiotics such as LIN,OTC and CTC,and the removal efficienc ies were 100%,76.37%and63.27%respectively.For feces,the pig farm feces treatment process had good removal effects on14 antibiotics such as SMDM,CIP,ENR,TIL,CTC and DMC,and the removal efficienc ies were24.40%～100.00%.The cattle feces treatment process had good removal effects on 4 antibiotics such as LIN and TC,and the removal efficiencies were 36.11%～100%.And the removal effect of composting treatment on cattle farms was better than that of sterilized and air-cured treatment.The chicken farm feces treatment process had good removal effects on 10 antibiotics such as OTC,SDMD,SQX,ENR,OFL,LIN and CTC,and the removal efficiencies were 90.95%-100%.（4）Farm manure treatment processes had a certain removal effects on ARGs.For livestock and poultry wastewater,the treatment processes in pig farm and cattle farm could remove most of the ARGs,especially the tetracycline ARGs,with the relative abundance reduced by 0～2.09 logs.In addition,the anaerobic fermentation unit and storage unit in the wastewater treatment process of the pig farm had better removal effects on ARGs,and the adjustment tank unit in the wastewater treatment process of the cattle farm has a better effect on the removal of ARGs.For livestock and poultry feces,the ex-situ fermentation bed,composting and aseptic drying could remove most of the target ARGs.After the pig feces was treated in the ectopic fermentation bed,the abundance of10 ARGs decreased,with an average decrease of 1.11 logs.After cow feces and chicken feces were composted,the abundances of 8 and 9 ARGs decreased,with average de creases of 0.83 logs and1.32 logs respectively.After the cow feces was sterilized and air-cured,the abundance of the five ARGs decreased,with an average decrease of 1.12 logs.It is worth noting that sulfonamide ARGs showed an upward trend in the above treatment processes.Therefore,the pollution caused by sulfonamide ARGs should be paid more attention. |
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