Study On The Exist Level Of Antibiotics In The Water Of The Huangbai River And Its Non-biodegradable Behavior

In recent years,with the widespread application of antibiotics,especially the excessive use of antibiotics in our country and non-compliance with standard discharge,the undecomposed antibiotics in the lake and natural water have been frequently detected.However,China has not formed antibiotic pollution control and control measures.Organized systematic research,lack of comprehensive survey and evaluation of antibiotic pollution in water environment.The Huangbai River is located in the middle of Yichang City and is a first-level tributary of the Yangtze River.It is the main source of water for industry,agriculture and domestic use in Yichang City.According to the analysis of the socio-economic development and pollution of the Huangbai River,there is potential antibiotic contamination in the basin.The development of phosphate rock and iron ore is the main watershed in the basin.The existence of natural minerals requires in-depth study on the degradation law and mechanism of antibiotics.Therefore,in this paper,based on the monitoring of antibiotic contamination characteristics in the Huangbai River,the pollutants of the cephalosporin antibiotics（CEPs）that are more toxic to the photo-transformation products in the environment are selected as the research object,and the most abundant and most catalyzed crusts are selected.The active sites of iron oxide minerals are representative of natural minerals.The hydrolysis and photolysis behavior of CEPs on the surface of iron minerals was explored.UPLC-MS/MS technology was used in combination with active species test experiments.The mechanism of the influence of natural minerals on the degradation of CEPs pollutants in water environment is further revealed.The main contents are as follows:1.Taking Huangbai River as the research object,the concentration of 18 kinds of antibiotics in the Huangbai River was determined by solid-phase extraction-high performance liquid chromatography,and the risk of antibiotics detected was evaluated.The results showed that 12 antibiotics including sulfonamides,tetracyclines,quinolones,cephalosporins,and chloramphenicol were detected in the Huangbai River Basin,among which sulfisoxazole had the highest concentration of antibiotics,up to 500 ng/L or more.Sulfamonomethoxine,sulfisoxazole,doxycycline,and florfenicol were the main antibiotics in the catchment.The detection rate was between 33.3 and 100%.The concentration of antibiotics in the water samples collected near the farms,in densely populated and river water pools is high.In addition,risk assessments showed that doxycycline and lomefloxacin have high risks for sensitive aquatic organisms,among which doxycycline has the highest ecological risk and involves more regions.Sulfamonomethoxine,florfenicol,and tetracycline are at moderate risk,while the remaining antibiotics tested are at low risk.2.Using Cefradine（CRD）as the target pollutant,the effects of 9 minerals on the hydrolysis were studied.It was found that the natural hematite has the greatest promoting effect on the hydrolysis of CRD,and the degradation rate of CRD is above 75%.The degradation products were detected by UPLC-MS/MS.The results showed that the natural hematite was mainly degraded byβ-lactam bond（hydrolysis）,oxidation,cyclization,and coordination with Fe（III）.The inhibition zone experiment proved that the antibacterial activity of the degradation fluid was reduced.At the same time,natural hematite was used to determine the hydrolysis properties and degradation products of other cephalosporin antibiotics such as cephalexin,cefotaxime and cefoxitin,which have higher detection rates in the water environment.The degradation pathways of the three antibiotics were the same as those of CRD,indicating that the hematite-catalyzed degradation of cephalosporin antibiotics is universal.3.The effect of dissolved organic matter in water on the hydrolysis and photolysis of natural hematite catalyzed CRD was studied.The results showed that the dissolved organic matter could promote the hydrolysis of CRD by natural hematite.The degradation rate of CRD increased from 60.7%to 92.6%in the presence of humic acid,and the degradation rate of CRD increased to 90.2%in the presence of humic acid.However,as the concentration of humic acid（50-100 mg/L）increases,the effect on the hydrolysis of cephradine is less,and as the concentration of humic acid（50-100 mg/L）increases,the hydrolysis of cephradine proceeds.Inhibition.In the photolysis experiment,under the visible light conditions,the degradation efficiency of cephradine in the humic acid/hematite coexisting system was significantly enhanced compared with the hydrolysis experiment in the same system.Under simulated sunlight conditions,the UV light in the light source causes the degradation rate in the homogeneous system to be faster than in the heterogeneous system.However,with different concentrations of humic acid in the degradation of cephradine in the hematite system,high concentrations inhibit the degradation of cephradine,and low concentrations promote the degradation of cephradine.In general,the coexistence of dissolved organic matter and minerals in natural waters has an effect on the degradation of cephradine.The hydrolysis and photolysis products were analyzed by UPLC-MS to obtain the hydrolysis and photolysis pathways.4.The mechanism of photodegradation of cephradine in goethite in H₂O₂ system was studied.Combined with response surface analysis,the most critical factors affecting the photolysis of pollutants in water and the combination of the best environmental factors were obtained.The results showed that the best combination of environmental factors was H₂O₂ concentration equal to 4.0 mmol/L and p H value of 5.0.The amount of goethite was1.2 g/L,and the illumination time was 9.0 h.The most critical factor affecting the photolysis of CRD is H₂O₂ concentration（x₁=68.50%）.On the mechanism side,on the basis of the conclusions of the response surface analysis method,the effects of different concentrations of goethite,different concentrations of H₂O₂,and different p H conditions on the photodegradation of CRD were studied.The results showed that the optimum amount of goethite was 1 g/L.The photodegradation efficiency was highest at p H=5.0,although the optimum H₂O₂ dosage was not obtained,but the final degradation rate of CRD was basically the same when the H₂O₂ concentration was increased from 5 mmol/L to 9mmol/L.To save material,5 mmol/L was selected.For the best amount of H₂O₂.At the same time,UPLC-MS was used to analyze the photolysis product under the condition of p H=5.0.It was concluded that the photochemical degradation of goethite mainly affected the surface of goethite through the interaction of H₂O₂ with goethite,and then Br?nsted alkali and Fe（IV）=O were generated through visible light activation interacts with cephradine adsorbed at the goethite interface and promotes the hydrolysis of theβ-lactam bond in the cephradine molecule.The production of the product is mainly through hydrolysis,cleavage,oxidation,and coordination ofβ-lactam bonds.