Screening And Source Identification Of Priority Control Antibiotics In Shitoukoumen Reservoir In Changchun

In recent years,antibiotics have been frequently detected in the water environment,and it has been studied the level of antibiotic endowment,spatial and temporal distribution characteristics,environmental behavior,and ecological risks in the water environment such as rivers,lakes,and reservoirs.The processes of hydrodynamics and water heat exchange in reservoir are different from rivers.Meanwhile,surface water bodies in northeast China have a five-month freezing period,and closed ice caps are formed.Studies on reservoirs without ice cover formation have shown that reservoir water has the potential to reduce the level of antibiotic pollution in its inflowing river water,and the abatement pathway varies from season to season.However,there are few studies on the occourrence and spatial and temporal distribution of antibiotics in reservoirs with ice cover formation and their inflowing rivers in northeast China.Therefore,this study was conducted on the Shitoukoumen Reservoir and its inflowing river in Changchun city.The concentrations of 23 antibiotics of six categories including eight quinolones,six sulfonamides,three tetracyclines,three chloramphenicols,two macrolides,and one lincomycin were detected in water and ice.The occurrence of target antibiotics in the reservoir and its inflowing rivers was explored.The concentrations of target antibiotics in the reservoir and its inflowing river water during the ice-free and ice-covered periods were analyzed to their spatial distribution.The monthly mass load of the inflowing rivers on the antibiotic input into the reservoir water was calculated.Finally,the correlation between priority control of antibiotics and water quality indicators,as well as the source of priority control of antibiotics,was studied.The study reached the following conclusions: for Shitoukoumen Reservoir and its inflowing river,the concentrations of the 23 target antibiotics in reservoir water and ice ranged from non-detect(n.d.)to 353.6 ± 35.1 ng/L and n.d.to 33.5 ± 3.2 ng/kg,respectively,and in river water and ice ranged from n.d.to 432.9 ± 30.0 ng/L and n.d.to 38.8 ± 0.2 ng/L,respectively.Among them,florfenicol were at higher concentration levels compared to some reservoir antibiotics in domestic and international studies.In the reservoir,the total concentration of antibiotics in the water at the sampling point closer to the southern intake of the reservoir was the highest,and there was a positive correlation between the concentration of antibiotics in the water at this sampling point and the concentration of antibiotics in the water in the nearby inflowing river.The way of antibiotics into the reservoir water,besides the input from the inflowing river,there could be other exogenous inflowing in different sampling periods.And the formation of ice caps could also affect the concentration levels of antibiotics in reservoir water.And the formation of ice caps could also affect the concentration levels of antibiotics in reservoir water.The reservoirs could have the effect of reducing antibiotic concentrations in river water in December 2020 and April 2021.When studying the remittance of target antibiotics into the reservoir through the inflowing rivers,the largest monthly mass loads of antibiotics were input into the reservoir water from the Shuangyang River and the Chalu River,where 22 antibiotics except norfloxacin were mainly remitted to the reservoir from the Shuangyang River and Chalu River.Through the study of priority control antibiotics in reservoir water,seven antibiotics and eleven priority control antibiotics were screened in the ice-free period and ice-covered period,respectively.Among them,florfenicol was greatly affected by the actual environmental concentration index;tylosin was greatly affected by the potential environmental risk index.In reservoir water,there were some correlations between priority control antibiotics and water quality indicators.In the ice-free periods and ice-covered periods,the most important source of the priority control antibiotics in the reservoir water were aquaculture and livestock and poultry breeding,respectively.Pipemidic acid,ofloxacin,and florfenicol were the same as the main sources in both periods.This study elucidates the occurrence and distribution of antibiotics in a reservoir and its inflowing rivers in northeast China and the screening method of priority control antibiotics,providing a scientific basis for the screening of priority control antibiotics in cold region reservoirs and their monitoring and pollution control.