| In recent years,Antibiotics have been widely used in disease treatment and livestock production,and have played an important and active role in promoting animal growth and improving the quality of poultry and livestock products.Since only a small part of these antibiotics are absorbed in humans and animals,most of them are directly excreted from urine and feces in the form of metabolites,and enter the water environment through medical and pharmaceutical wastewater,domestic industrial wastewater,and livestock breeding wastewater,and act Because of environmental organisms,it poses incalculable potential threats to human health and the ecological environment.This paper takes Xiangjiang River,the largest river in Hunan Province,as the research object,collects surface water samples of the main stream of Xiangjiang River and 11 main tributaries in summer(August)and winter(December),and uses high performance liquid chromatography to detect 5 typical antibiotics(oxygen).Concentration levels of floxacin(OFX),sulfamethoxazole(SMX),sulfadiazine(SD),oxytetracycline(OTC)and sulfamethazine(SMZ)),explore the spatial distribution characteristics of different antibiotics;analyze antibiotics The characteristics of the change of the level in different seasons;at the same time collect and determine the relevant physical and chemical indicators of the water environment(total organic carbon(TOC),total phosphorus(TP),ammonia nitrogen,pH,etc.)and sediment physical and chemical indicators(pH,mechanical components,organic matter)Content)and antibiotics were analyzed;the ecological risk quotient method(RQs)was used to evaluate the ecological risk of antibiotic residues in the Xiangjiang River.The main conclusions are as follows:(1)The detection rate and detection concentration level of antibiotics vary with the type of antibiotics.Antibiotics at 35 sites in the surface waters of the Xiangjiang River were tested,and the results showed that all five antibiotics were detected at different concentrations,and the concentration level was at the ng/L level.The highest detection rate is OFX,the detection rate is 100%,the concentration range is 0.064～324.544 ng/L,the detection rate of SMX is 97.14%,the concentration range is nd～420.12 ng/L,and the detection rate of SD is 57.69%,concentration range nd～96.21 ng/L,OTC detection rate 23.08%,concentration range nd～82.6 ng/L,SMZ detection rate 36.54%,concentration range nd～66.756 ng/L.(2)The spatial distribution characteristics of 5 antibiotics.The concentration levels of the five antibiotics in the upper,middle,and lower reaches of the Xiangjiang River are significantly different,and they show that the downstream section>middle reaches>upstream section.The average concentrations of the upper,middle and downstream antibiotics are 5.98 ng/L,6.02 ng/L and 6.947 ng/L,respectively.However,the difference in the average concentration of different antibiotics in the upstream,midstream and downstream is different.The OTC performance is downstream>middlestream>upstream.The average concentrations in the upstream,midstream and downstream are 0 ng/L,0.399 ng/L and 0.908 ng/L respectively;SMX performance is Downstream>upstream>midstream,the upper,middle and lower reaches are 5.694 ng/L,1.922 ng/L,and 6.064 ng/L respectively;SMZ,SD,and OFX all appear as midstream>downstream>upstream,where SMZ is averaged in the upper,middle and lower reaches The concentrations are 0.002 ng/L,1.49 ng/L and 0.249 ng/L,SD is 0.006 ng/L,1.473 ng/L and 0.155 ng/L,OFX is 0.277 ng/L,1.185 ng/L and 0.165 ng/L.The detection rate and average concentration of the 5 antibiotics in the 11 main tributaries were significantly higher than those in the mainstream of the Xiangjiang River.The average concentrations of OTC in the tributaries and the main stream were 1.32 ng/L and 0.194 ng/L,respectively,and the SMX was 3.942 ng/L And 3.614 ng/L,SMZ is 0.039 ng/L and 0.0007 ng/L,SD is 0.235 ng/L and 0.006 ng/L,OFX is 0.198 ng/L and 0.192 ng/L.At the same time,the concentration of antibiotics in the water body basically increased after the tributaries merged into the main stream,which has an enrichment effect on the antibiotic content of the main stream.The content of antibiotics in distilled water,Leishui,and the four tributaries of Liuyang River and Laodao River was greater than that in the main stream,which showed dilution through the main stream,and the concentration of antibiotics decreased.(3)There is a certain correlation between antibiotics and physical and chemical indicators of water bodies.OFX concentration and TOC are extremely significantly positively correlated(P<0.01),SMZ concentration and redox potential are significantly positively correlated(P<0.05),SD concentration and pH are significantly negatively correlated(P<0.05),OTC concentration and sediment pH showed a very significant negative correlation(P<0.01);there is generally a significant positive correlation between the same class of antibiotics,such as SD and SMZ have a very significant positive correlation(P<0.01).(4)All five antibiotics showed a significantly higher content in winter than in summer.The average concentration of SMX in summer and winter was 3.72 ng/L and 192.19 ng/L,the average concentration of SD in the two seasons were 0.078 and 31.019 ng/L,and the average concentration of OTC in the two seasons was 0.547 ng/L and 24.096 ng/L,respectively.The average concentrations of L and SMZ in the two seasons were 0.013 ng/L and 11.669 ng/L,respectively,and the average concentrations of OFX in the two seasons were 0.194 ng/L and 67.63 ng/L,respectively.(5)The ecological risk quotients of the 5 antibiotics to the tested species are different.In summer,SMX shows a medium risk level for algae organisms in water bodies(0.1≤RQs<1);OTC shows a low risk for the three tested species(RQs<0.1);SD shows a low risk for aquatic organisms(RQs<0.1);OFX and SMZ are risk-free.In winter,SD shows a high risk to aquatic organisms(RQs ≥ 1);a medium risk to Moina(0.1≤RQs<1);OFX shows a medium risk to invertebrates(0.1≤RQs<1);and SD,SMZ and OTC all showed low risk to the tested species(RQs<0.1). |
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