Occurrence Characteristics Of Typical Contaminants In The Aquatic Environment Of A Newly-built Water Source Area

With the development of economy and society,the amount of pollutants which were produced in human life discharged into water bodies are increasing.In order to have a better life,people pay more and more attention to the safety of drinking water sources.In order to increase the safety and quality of drinking water,Jinze Reservoir,a new drinking water source was selected as the research area.We choose traditional pollutants represented by N?P and DOM,and selected antibiotics as the representative of emerging pollutants to assess environmental risk and analyze their distribution,16 sampling points were set up in Taipu River,industrial area,agricultural area,residential area,agricultural area and Jinze Reservoir area.This work systematically studied spatial and temporal distribution characteristics of contaminants,the distribution behavior of antibiotics between water bodies and sediments in four seasons,and explore the change of DOM which was affected by antibiotics.In this study,the national standard method was used to determine the conventional water quality index and the water quality evaluation was carried out.The eutropHication status of the water body was evaluated by calculating the nitrogen-pHospHorus ratio and the comprehensive nutritional status index.Twenty-two kinds of antibiotics were studied by solid pHase extraction and ultra-high liquid chromatograpHy-triple quadrupole mass spectrometry.At the same time,ecological risk assessment of antibiotics and priority control antibiotic screening were carried out.The distribution characteristics of FDOM were studied by three-dimensional fluorescence spectroscopy combined with parallel factor analysis.A fluorescent titration experiment was designed to study the effect of antibiotics on DOM.Based on the above research,a deep understanding of the occurrence characteristics and environmental behavior of typical pollutants in the water environment of Jinze were obtained.The results are shown as follows:?1?The annual water quality in Jinze-Area is in the category II to V,except for the TN in the reservoir area.The concentration of TN is at a high level,the NH₄⁺-N content is lower,and TP and CODMn are at a higher level,showing regional and seasonal differences.The results of eutropHication evaluation sugggested that algae growth in the Jinze area was in a P-restricted state for most of the time and in the region,and changed from P-limit to nitrogen-pHospHorus to promote the state with time,and finally turned to the N-restricted state.The level of eutropHication fluctuates between oligotropHic and highly eutropHic states,most of which are in the middle nutrient state;from the time changing,it shows the trend of autumn>summer>spring>winter.?2?Characteristics of antibiotics in Jinze Area:Sixteen kinds of antibiotics were detected in water,the detection rate was above 50%,and the detected concentration was between77.65ng/L and 1862.31ng/L.Sulfonamides and tetracyclines were the main antibiotics.Seventeen antibiotics were detected in sediments,the detection rate was close to 50%or higher than it,and the detected concentration was between 41.80 and 476.23 ng/g.Quinolone,?-lactam and tetracycline were the main antibiotics.The antibiotics in water and sediment samples elicited regional and seasonal differences,the culture and living areas were higher than that in other areas.These in spring and winter are higher than them in summer and autumn.The distribution coefficient of antibiotics between water bodies and sediments is:quinolones>?-lactams>macrolides>tetracyclines>sulfonamides>other classes.The risk entropy evaluation showed that Ergomycin?ETM??Enrofloxacin?EFX??Sulfadiazine?SDZ??Norfloxacin?NFX??Tetracycline?TC?and Doxycycline?DC?were in moderate or high risk in water,with the highest risk in winter,followed by spring and autumn,and the lowest risk in summer.The priority control antibiotic screening results showed:SDZ in sediments has a higher enrichment potential than other antibiotics,and CFX has a tendency to reduce pollution.?3?Anti-DOM occurrence characteristics in Jinze area:DOC concentration in water body of Jinze area was between 5.50 and 25.00mg/L,and a?350?is between 2.69?8.50m^-1?a?350?is used to indicate the amount of CDOM's change?,the change of DOC and DOM content has regional and seasonal differences;the SUVA₂₅₄ water body is between 0.63 and 2.52L/?mg·m?,the degree of aromatization shown the highest in autumn,followed by spring and winter.summer was the lowest.Three-dimensional fluorescence spectroscopy combined with PARAFAC analysis showed that the water FDOM consists of three components:component 1?C1,Ex/Em=230/345nm?aromatic protein;component 2?C2,Ex/Em=230,275/320 nm?a tryptopHan-like fluorescent component in the ultraviolet region;a humus-like substance in the visible region of component 3?C3,Ex/Em=245/430 nm?.The distribution characteristics are:in four seasons,the relative fluorescence intensity of C1 component fluctuates between 0.19Ru and 21.50Ru,and there is no significant seasonal difference?p>0.05?;C2:no significant seasonal difference?p>0.05?,the detection rate was62.5%in autumn,the change detected amount was large,showing that in reservoir and downstream areas were higher than that in other areas;C3 fluctuated between 0.05Ru and5.44Ru with a greatly content chang,C3 in autumn is extremely significant?p<0.01?higher than winter,spring and summer.The total fluorescence intensity shows:the trend of upstream>the near reservoir>downstream>reservoir.Look at in the perspective of land use type,the fluorescence intensity of industrial area,residential area and agricultural area is higher than that in reservoir area and living area in winter,spring and summer;The bio-index BIX,the humification index HIX and the fluorescence index FI analysis showed that there were more new DOM in the water and with a low humification degree and significant endogenous production characteristics.Pearson's correlation analysis showed that there was a significant positive correlation between T,pH and DOC content and C3;SUVA₂₅₄54 was positively correlated with C1 and C2?p<0.05?.?4?Effect of antibiotics on DOM:Parallel factor analysis was used to analyze the EEMs of DOM obtained four kinds of fluorescent components:component 1?C1,Ex/Em=290/445nm?,component 2?C2,Ex/Em=290/500nm?,component 3?C3,Ex/Em=275/460 nm?three humic acid components and component 4?C4,Ex/Em=230/440 nm?one fulvic acid component.The effects of sulfadiazine?SDZ?,tylosin?TYL?,tetracycline?TC?,norfloxacin?NFX?and doxycycline?DC?on the fluorescence components in DOM were investigated by fluorescence titration experiments.The results showed that:SDZ,TYL,and DC have a quenching effect on C3,the higher concentration of antibiotics,the stronger quenching effect on C3;It also enhanced C1 and C4 components.TC significantly enhanced the fluorescence intensity of the C2 component in DOM while shifting the peak C to the right;the fluorescence intensity of component C4 increased with increasing TC concentration.NFX has an enhanced effect on the fluorescence intensity of C1,C3 and C4.The C3 component of a certain concentration of DOM can be completely quenched when both SDZ and TC antibiotics were at high concentrations.TYL and DC partially quench the C3 at high concentrations;C4 is partially quenched at low concentrations of TC.