Study On Antibiotic Resistance Genes Pollution In Urban Domestic Waste Landfills Of Zhejiang Province

Landfill is the ultimate disposal site for municipal solid waste?MSW?and the important source of antibiotics resistance genes?ARGs?.At present,significant progress has been made in the pollution of antibiotic resistance genes in urban sewage treatment plants,farmland soils,watersheds and other waters,but there are relatively few studies on antibiotic resistance genes in landfills.Based on this,this study selected 10 different municipal solid waste landfills in Zhejiang Province,combined with physical and chemical detection,high-throughput quantitative PCR and biological information analysis,the pollution level,and distribution characteristics,influencing factors and temporal and spatial changes of ARGs in landfills were studied.This not only helps to enrich the environmental data of antibiotic resistance gene pollution in China,but also provides a reference for the risk control of landfill resistance gene contamination.The main results obtained are as follows:?1?The antibiotic and ARGs of landfills in Zhejiang Province are seriously polluted in Jiaxing,Shaoxing,Lishui and Wenzhou.Fluoroquinolone,macrolides,sulfonamides and?-lactam antibiotics detected the highest concentration in Jiaxing landfill,with concentrations of1406.85?g/kg,127.61?g/kg,16.60?g/kg and 3.48?g/kg,respectively.The concentration of tetracycline antibiotics in Shaoxing landfill is the highest,reaching 1011.04?g/kg.ARGs are common in landfills,and qnrD,qnrS,mexF,ermA,ermB,mefA,sul1,sul2,tetM,tetX and tetW are highly polluted in Jiaxing,Wenzhou and Lishui landfills,and the abundances are above 10^-4?ARGs/16S rRNA?.The ecological risk of antibiotics in Jiaxing landfill is higher.The risk quotient methods?RQs?of ofloxacin,norfloxacin,sulfamethoxazole,oxytetracycline and ampicillin are all greater than 1,which is a high-level ecological risk.The abundance of qnrS,mefA,sul1,tetQ in Jiaxing and Wenzhou is higher than 10⁸ copies/g,which has a high potential risk.?2?Variance partitioning analysis?VPA?shows that mobile genetic elements?MGEs?are the main factors affecting the abundance of ARGs in landfills,with a contribution rate of 50.6%.The contribution of environmental factors,antibiotics and heavy metals to ARGs accounted for only 13.8%,6.8%and 2.1%,respectively.Redundancy analysis?RDA?showed a significant positive correlation between intl1 and sulfonamide ARGs?sul1 and sul2?in landfills?p<0.01?.Transposon genes are closely related to ARGs of fluoroquinolones,tetracyclines and macrolides.There was no significant correlation between antibiotics and the corresponding ARGs,but macrolide antibiotics showed a significant positive correlation with other ARGs?such as sulfonamides,sul1 and sul2?,which may be the result of low or co-selection of antibiotics.There was a significant positive correlation between pH and ermA,ermB,mefA,tetX,tetM,tetW,qnrS and mexF?p<0.05?.Nitrate mainly affected the abundance of sul1 and sul2?p<0.01?;Cr and Zn and sul1 and sul2 was significantly positively correlated?p<0.05?.?3?The residual antibiotics in landfills tend to decrease with the increase of landfill age.The concentration of sulfonamides,macrolides,tetracyclines and?-lactam antibiotics in the initial landfill was 2 to 3 times higher than that in the later stage of landfill.The abundances of tetM,tetX,ermB,qnrS,sul1,and sul2 hasve always dominated in all landfill wastes,and the abundance of ARGs in refuse decreased with the increase of landfill age.The absolute abundance of ARGs in the initial landfill was 9.94±0.46 log₁₀?copies/g?,which was about 0.4¹orders of magnitude higher than the medium and late refuse.