| Quinotone antibiotic(QNs)are widely used in medicine,aquaculture and so on.However,they are not completely absorbed by organisms,and almost are excreted in the form of parent compounds or metabolites,which has attracted people's attention.The distribution,sources and risk assessment of 8 quinotone antibiotics in surface sediments from coastal zones and estuary wetlands in Jiaozhou Bay were analyzed in the study.The relationship between concentration of QNs and total organic carbon(TOC)was surveyed and pigment was used to reflect the influence of QNs on wetland plants.The results indicated that the pollution levels of QNs in the coastal zone of Jiaozhou Bay were low,,and there was no significant positive correlation with the content of TOC,but it affected the growth of vegetation to a certain extent.The results were as follows:An analytical method for simultaneous determination of 8 quinolone antibiotics in marine sediments with high performance liquid chromatography was established.Extract efficiency of 3 kinds of solid phase extraction columns--Agilent Plex Bond(500 mg,6 m L),Waters HLB oasis(200 mg,6 m L),Waters HLB oasis(500 mg,6 m L)was investigated and efficiency of Waters HLB oasis(500 mg,6 m L)was higher.Thus,Waters HLB oasis(500 mg,6 m L)was used to pretreatment experiment,such as Sample extraction,elution buffer,ultrasonic time.The results showed the recovery was higher when samples were ultrasonically extracted in 50%Mg(NO3)2/5%NH3·H2O for 30 minutes,then cleaned by Waters HLB oasis(500 mg,6 m L),and finally eluted with 15 m L acidic acetonitrile.The quinolone antibiotics were separated on Agilent ZORBAX Eclipse XDB-C18(5 ?m,150 mm×4.6 mm i.d)using a mobile phase of acetonitrile-phosphoric acid solution(p H=3)and detected at excitation and emission wavelength of 285 nm and 460 nm,325 nm and 365 nm.The optimized method is simplicity and high sensitivity,and is applied to simultaneous analyse the eight quinolone antibiotics in marine sediments.The content of quinolones in the surface sediments of the coastal zone of Jiaozhou Bay was determined by the method established in the laboratory.The concentration ranged from 0.478 ng/g to 47.545 ng/g(mean value 8.449 ng/g),which were really low compared to other coastal zones around of China and foreign rivers.A relatively high level of was found in population,hospital intensive urban areas,main sewage outlets and offshore estuaries.The highest concentration of antibiotics of the sites was near the densely hospitals and populated areas.The highest detect frequency of oxolinic acid is related to its widespread use in aquaculture industry.Sites in Red Island Wharfs and breeding areas were found many of QNs.The average concentration of the sediments in Yang River estuary was higher than that in Dagu River estuary.Thus,it indicated that the study area has been polluted by the QNs.The obvious positive correlation between OFL,OA and TOC in surface sediments of Jiaozhou Bay coastal zone was found using Principal component anylysis,while no significant positive correlation was observed between another six QNs with TOC,which could be related to its relatively low concentrations and detection frequencies.Compared with the sediments from other seas and rivers all over the world,the concentration of QNs in sediments from Jiaozhou Bay was relatively low.However,much more attention should be paid as high concentration and detection frequency of QNs were occurred in the study area.The distribution,sources and risk assessment of 8 quinotone antibiotics in surface sediment from typical estuary wetland in Jiaozhou Bay(Dagu River and Yanghe estuary wetland)were analyzed in the study.The results showed QNs were detected in all the samples,and the total QNs concentration of Yanghe and Dagu estuary wetland ranged of 0.276 ~ 5.229 ng/g and 0.917 ~ 2.460 ng/g,with a mean value of 2.455 ng/g and 1.444 ng/g.The highest concentration occurred in inner Yanghe wetland,near aquaculture industry.A positive correlation between ENR concentration and TOC,OFL concentration and TOC was observed for the investigated areas.However,for the other six QNs,no significant correlations were found between concentration and TOC,which could be related to its relatively low concentrations and detection frequencies.Principal component anylysis suggested that QNs originated from various source,mainly depending on wastewater discharge,which used in hospital,human and aquaculture.Risk quotients indicated current level of OFL might be at medium risk,while other QNs were all at low risk.And RQ was calculated by MEC/PNEC.Compared the concentration of QNs and pigment,we found that QNs in sediment samples of wetland has inhibitory effect on the growth of vegetation.The distribution of QNs in different medium such as sediment samples,water samples and plants samples was different,in connection with octanol-water partition coefficient and TOC,the higher octanol-water partition coefficient and TOC,the higher QNs in sediment sample,the lower transfer factor to plants.The depositional flux of QNs in Jiaozhou Bay during the recent 100 years revealed that QNs in sediments were related to aquaculture industries,industries and domestic sewage.The peak value of QNs was detected in 1988 year with the concentration of 35.293ng/g,because the aquaculture industry had a bumper harvest.While a depressed trend was found from 2015 to 2016 year,Department of agriculture announced that since December 31,2015,stop using some QNs production.By linear fitting,there was no significant positive correlation between QNs content and TOC in columnar sediments.The concentration of pigment of different depth in columnar sediments was determinated,and the results indicated that pigment exhibited a decreasing trend from surface to bottom.Besides,a significant negative correlation was observed between QNs and pigment in corresponding depth.Therefore,we deduced that QNs in sediment samples could have inhibitory effect on the growth of wetland vegetation.The same time,an obvious positive correlation between TOC and pigment was discovered in the columnar sediments. |
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