Occurence Characteristics And Assessment Of Nitrogen,phosphorus,Antibiotics And Antibiotic Resistance Genes In Jinze Reservoir And Surrounding Area Of Taipu River

The Jinze Reservoir is a newly-built reservoir in Shanghai in 2016.It takes water from the Taipu River and provides water for Qingpu,Minhang,Songjiang,Fengxian and Jinshan Districts.It is the second largest water source in Shanghai after Qingcaosha Reservoir.To monitor and analyze the occurrence characteristics of conventional pollutants(nitrogen,phosphorus and organic pollutants)and emerging polltyants(antibiotic and antibiotic resistance genes)in Jinze reservoir and surrounding area of Taipu River is of great significance to ensure the safety of water quality and take effective prevention and control measures.In this study,14 sampling sites in the study area were collected and monitored for one year.The GB method was used to test the physical and chemical indicators and conventional pollutants of water bodies.Six kinds of 18 antibiotics were tested by ultra performance liquid chromatography-triple quadrupole mass spectrometer.High-throughput fluorescence quantitative reaction and real-time fluorescent quantitative PCR were used to detect the abundance of 295 antibiotic resistance genes and mobile genetic elements.On this basis,the physical and chemical indicators of water quality,conventional pollutants,antibiotics and antibiotic resistance genes in Jinze reservoir and surrounding area of Taipu River,correlation relationship,water eutrophication level and ecological risk of antibiotics were analyzed and evaluated.The main conclusions are as follows:(1)The nitrogen concentration at each sample was TN>NO3--N>NH4+-N>NO2--N,the annual TN concentration was 0.72-3.48 mg/L,the occurrence level is high;TP concentration is 0.006-0.470 mg/L,the occurrence level is low,basically reached class Ⅱ standard;the organic pollution level is high;Chl a concentration in summer and autumn is 4.70-225.27 μg/L;TLI(Σ)is 51.68-82.89,the water source region was in eutrophication state.(2)18 antibiotics were detected in the water samples.The concentrations were:sulfonamides(10.48-1261.00 ng/L)>tetracyclines(8.10-607.90 ng/L)>quinolones(5.95-352.52 ng/L)β-lactams(1.79-289.85 ng/L)>macrolides(0.25-93.52 ng/L)>others(0.14-51.17 ng/L).The concenteation in Taipu River was generally lower than the Jinze Reservoir and surrounding area,and reservoir inlet>reservoir.According to the RQs evaluation method,the risk levels of AMX,PEN V and TC were the highest in the waters of the study area.14 antibiotics were detected in the sediment samples.The concentrations were:quinolones(3.54-69.70 ng/g)>tetracyclines(3.99-66.85 ng/g)β-lactams(1.51-87.64 ng/g)>Sulfonamides(3.67-20.09 ng/g)>macrolides(1.07-17.01 ng/g).The two living areas have the highest concentration throughout the year.The water and sediment samples showed a trend of high in spring and winter and low in summer and autumn.(3)The number of detected ARG species was 84-159,and the number of sediment samples was 72-87.The types of ARGs resistance mechanisms are mainly antibiotic deactivate and efflux pump mechanism;among the ARGs detected in water and sediment samples throughout the year,the multidrug ARGs,aminoglycoside ARGs and sulfonamide ARGs were the most abundant,and multidrug>aminoglycoside>sulfonamide.The ARGs abundance of the sampling sites in the water and sediment samples were the lowest in summer and the highest in spring.The correlation analysis showed that antibiotics are greatly affected by physical and chemical indicators and conventional pollutants of water bodies.ARGs were less affected and had no corresponding correlation with antibiotics.And the tnpA-05(MGEs)played an important role in the horizontal migration of ARGs in water.