Characteristics Of Antibiotic Distribution And Ecological Risk Assessment In Typical Landscape Lakes In Xi’an

As a new pollutant,antibiotics have been detected in many river,lakes and even drinking water in China.Although the detected concentration is very low,it can have irreversible toxic effects on living organisms,and can increase the potential risk through the food chain.Xi’an is located in the middle of Guanzhong Plain,and has been known as "eight waters around Chang’an" since ancient times.However,with the continuous development of urbanization,the lake water environment pollution in Xi’ an has become more and increasingly serious.This paper conducted the systematic study of antibiotics in typical landscape lakes in Xi’an,analyzes the pollution distribution characteristics of antibiotics in lake water bodies,and uses the stress experiment of antibiotics on algae to determine the risk ent ro py toxicity.The main research results include:(1)Antibiotic concentrations were ng/L in all four lakes;from the detection rate and detection concentration,Sulfamethoxazole(SMX),Sulfamonomethoxine(SMM),Ofloxacin(OFX),Erythromycin(ETM),Roxithromycin(RTM)and Oxytetracycline(OTC)are the main antibiotic types in Xi’an Lake;the seasonal difference of antibiotics was obvious.Sulfamethoxazole(SMX),Of loxacin(OFX),Oxytetracycline(OTC)antibiotics,Macrolides(ETM、RTM)antibiotics in winter;Compared to domestic lakes,Antibiotic concentrations in typical lakes in Xi’an were moderate to lower level;The correlation between pH、COD、DO and NH3-N and antibiotics in lakes,pH has the greatest impact.(2)There are obvious seasonal and spatial differences in the microbial community structure in typical lakes in Xi’an.The relative abundance and diversity of microorganisms in winter is higher than that in summer,and the abundance of water intake is higher than that in the center of the lake;Proteobacteria,Actinobacteria,Bacteroides and Cyanophyta are the dominant phyla;TN,TP,NH3-N,COD in typical lakes in Xi’an are related to Cyanobacteria,the center of the lake;Proteobacteria,Actinobacteria,Bacteroides and Cyanophyta are the dominant phyla;TN,TP,NH3-N,COD in typical lakes in Xi’an are related to Cyanobacteria,Actinobacteria and Bacteroides,DO is related to Acidobacteria,Gemmatimonadetes,Parcubacteria,Verrucomicrobia,Firmicutes,Chloroflexi.The bacterial phyla are related;different antibiotics have different effects on the microbial community in the lake.Among them,tetracyclines,macrolides and fluoroquinolone antibiotics have a greater impact on microorganisms,and sulfonamides have a smaller impact.(3)After three different antibiotic stresses,the cell concentration of Microcystis aeruginosa and Chlorella showed a trend of low concentration growth and high concentration inhibition,and the toxicity of the three antibiotics to Microcystis aeruginosa and Chlorella was Ofloxacin>Erythromycin>Sulfamethoxazole;The ecological risk assessment of typical lake water bodies in Xi’an was carried out by the risk entropy method,except for the Taohuatan sampling point,the Sulfamethoxazole(SMX)risk entropy value for the species is between 0.1 and 1,showing Medium risk,the remaining points show low risk levels,and fish have the lowest ecological risk in the three types of test subjects.Sulfamethoxazole(SMX)and Erythromycin(ETM)have relatively high ecological risks to green algae;using the MRQ method to calculate the potential risk of coexistence of multiple antibiotics increases with the accumulation.