Spatial And Temporal Distribution And Migration Of Typical Antibiotics In Nansihu Lake Basin

In recent years,antibiotic drugs have been widely used in medical and livestock breeding,resulting in the formation of"pseudo-persistence"phenomenon in the environment,and entering the water environment through waste water,feces and other means,posing potential threats to human body and ecological environment.In this paper,the content,time and spatial distribution of antibiotics in water,sediment and sewage treatment plants in the Nansi Lakes River basin were studied with four types of antibiotics（sulfonamides,quinolones,tetracycline and Macrolide）,and the effects of wetland system on the migration of antibiotics in the Nansi lake basin were studied.Finally,the risk assessment of antibiotics in the water body of Nansi Lake basin is carried out in order to provide basic data support for the prevention and treatment of antibiotic pollution in Nansi Lake River basin.The main results of this paper are as follows:In this paper,the antibiotic concentration in water and sediment of the 30 major inflow rivers and 6 wetland systems of Nansi Lake was detected by HPLC-MS/MS,and the detection limits of water and sediment samples are 0.060-0.462 ng·L^-1 and 0.070-0.875μg·kg^-1（S/N=3）,the quantitative lower limit is 0.120¹.285 ng·L^-1 and 0.192².438μg·kg^-1（S/N=10）,recovery rates of 70.30%-125.69%and 69.51%-106.17%respectively,all of which meet water and sediment testing requirements.（2）14 kinds of antibiotics were detected in the surface water and sediments of 30 major inflow rivers in Nansi lake and the concentration ranges of antibiotics in the water and sediments were nd-693.69 ng·L^-11 and nd-207.241μg·kg^-1,respectively.The spatial and temporal distribution law is as follows:in the surface water of 30 major inflow rivers,the total concentration of antibiotics in February(1449.433 ng·L^-1)>May(523.456 ng·L^-1)>August(453.492 ng·L^-1),while in sediments,the total antibiotic concentration of February(723.513μg·kg^-1)>Total antibiotic concentration in August(615.088μg·kg^-1);Total antibiotic concentration in surface water of Superior Lake（S1-S15）>Total antibiotic concentration in surface water of Lower Lake（S16-S30）,Total antibiotic concentration in Superior lake sediments(346.94-550.87μg·kg^-1)>Total antibiotic concentration in Lower lake sediments(172.644-268.148μg·kg^-1).The correlation coefficient（R²）of antibiotics in sediments and water of 30 major inflow rivers of Nansihu Lake was relatively low in both wet and dry water periods,all of which were 0.137.The risk assessment results obtained by the risk entropy method show that the risk of antibiotics in different water periods in 30 major rivers is dry season>level season>wet season,the different trophic grades showed as algae>plant>invertebrate>fish.（3）23 kinds of antibiotics were detected in the surface water of Xiaosha River wetland,and the concentration range of antibiotics in water was nd-517.316 ng·L^-1,antibiotic concentration range in sediment is nd-496.047μg·kg^-1;The total concentration of antibiotics in the surface water of Xiaosha River wetland in the dry season(3344.6 ng·L^-1)and the wet season(1934.544 ng·L^-1)and the level season period(1510.564 ng·L^-1)were respectively determined from high to low;While the experimental results in sediment are as follows:Total concentration of antibiotics in sediment wet season(6716.771μg·kg^-1)>level season(2280.628μg·kg^-1)>dry season(1981.264μg·kg^-1).The concentrations of norfloxacin（NOR）and Sulfonamides（SQL）were highest in 6 wetlands in the Nansi Lake basin,with cumulative concentrations of 251.080ng·L^-1 and 77.352 ng·L^-1;The cumulative concentrations of Ofloxacin（OFL）and Norfloxacin（NOR）in sediments were the highest with 805.768μg·kg^-1 and 427.959μg·kg^-1,respectively.The removal effect of Xiaosha River wetland on antibiotics in wet period（88.26%）was much higher than that in level water season（27.76%）and dry season（27.76%）;the removal of antibiotics in sediments was-71.45%in wet period,26.76%in level water period and 52.10%in dry period.In the Nansi Lake basin,the removal effects of antibiotics in water bodies in different wetlands were 88.26%（W1）,86.85%（W2）,80.71%（W3）,44.69%（W4）,81.23%（W5）and 55.2%（W6）.In Xiaosha River wetland,the correlation coefficients（R²）of water and sediment antibiotics in wet period,normal period and dry period were 0.068,0.299 and 0.750,respectively;while in the6 wetland systems of Nansi Lake,it was 0.830.The risk assessment results obtained by the risk entropy method showed that the risk of different trophic antibiotics in the nansihu wetland system was showed to be algae>plant>invertebrate>fish in descending order.（4）The PCA-MLR model was used to estimate the average contribution rates of each factor in the surface water of 30 main rivers entering Nansi Lake.The average contribution rates of each factor in dry season:B,C and D co-source（factor 1）:66.8%,D source（factor 3）:18%,A,B,C,D and other co-source（factor 5）:15.2%;the average contribution rates of each factor in plain season were A source（factor 1）:78.5%,A,B and C co-source（factor 2）:21.5%.The average contribution rate of each factor was:B source（factor 1）:59.6%,A,B,C and D source（factor 3）:20.7%,C and D common source（factor 4）:10.0%,A and D common source（factor 5）:9.7%.The PCA-MLR model was used to estimate the average contribution rate of each factor in Xiaoshahe surface water during dry season:S and L co-source（factor 1）:14.5%,S and L co-source（factor 2）:50.7%,S source（factor 3）:20.4%,S source（factor 4）:14.4%)and S and L co-source（factor 1）:58%,S and L co-source（factor 2）:19%,S source（factor 3）;and the average contribution rate of each factor in plain season was S and L co-source（factor 1）:58%,S and L co-source（factor 2）:19%,S source（factor 3）:17.1%,other sources（factor 5）:5.9%;the average contribution rate of each factor in flood season is:S and L co-source（factor 1）:52.4%,S source（factor 2）:21.6%,S source（factor 3）:18.1%,S and L co-source（factor 4）:7.9%.