| This reservoir is located at downstream of the Yangtze River.As an important water source in Shanghai,its water supply volume is 7.19 million m3/d,contributing for over 50%of the total raw water supply in Shanghai.At present,little research has been done on the antibiotics and antibiotic resistance genes from river system to reservoir system.Therefore,this paper selected the reservoir as the research object,analyzed its spatiotemporal distribution of antibiotics,the ecological risk of antibiotics and the distribution characteristics of antibiotics resistant genes.Four sampling points were set from May,2016 to April,2017.In this paper,the water quality was investigated and analyzed.17 antibiotics?sulfonamides,quinolones,?-lactams,macrolides,tetracyclines and other antibiotics?were detected by liquid chromatograph-tandem mass spectrometry system.295antibiotic resistance genes?ARGs??Sulfonamides,Tetracyclines,Chloramphenicol,?-Lactams,macrolide-lincosamide-streptogramin B,Aminoglycosides,Vancomycin,Multidrug and other antibiotic resistance genes?)were detected using High Throughput quantitative PCR.The main conclusions are as follows:?1?The reservoir has good purification ability of turbidity,total nitrogen,nitrate nitrogen,ammonia nitrogen and nitrite nitrogen.The concentration of ammonia nitrogen reached Grade I standard;the total phosphorus concentration and permanganate index reached Grade II standard of surface water;and the total nitrogen pollution of the reservoir was more serious,and the concentration was between Grade IV and V.?2?16 antibiotics were detected in the water.Sulfonamides,fluoroquinolones,?-lactams,macrolides,tetracyclines and others were detected with the concentrations of nd-163.19,nd-362.69 ng/L,nd-404.81ng/L,nd-37.36 ng/L,nd-266.74 ng/L and nd-95.67 ng/L,respectively.Only10 antibiotics were detected in the sediment,the concentration of sulfonamides was in the range of nd-99.68 ng/g,the concentration of fluoroquinolones was 0.58-11.38 ng/g,the concentration of?-lactams was nd-22.91 ng/g,macrolides was 0.41-3.91 ng/g,tetracyclines concentration was nd-7.94 ng/g.The results showed that the concentrations of antibiotics in sediment and water in summer were low,and the concentrations in winter were high.?3?The ecological risk assessment of antibiotics in the reservoir water indicated that the eight antibiotics had a low risk throughout the sampling period?RQ<0.1?;four antibiotics were at high risk throughout the year?RQ>1?.?4?The results elucidated that 129 and 149 ARG targets were detected positive in the water and sediment respectively.Antibiotic deactivate and efflux pump were the two major mechanisms of resistance genes in water and sediment.Multidrug ARGs,?-lactam ARGs and other ARGs had the highest relative abundance in water samples and sediments,and their monthly mean values in water were 1.77×10-2,1.16×10-22 and 2.61×10-2respectively;monthly mean values in sediment were 1.13×10-2,2.09×10-2and 1.40×10-22 respectively.Analysis of the absolute abundance of resistance genes found that the absolute abundance of resistance genes in the reservoir was higher than that of the extracellular compartment,with accumulation multiple of 1.76-401.56.Slow water flow and high biomass in the reservoir may be responsible for this phenomenon.Absolute abundances of integron?intI-1?clinical??were significantly correlated to the levels of total ARGs?R2=0.929,P<0.1?,which elucidated that integron can play an important role in ARGs transfer and accumulation. |
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