| Recently,the drug-resistant bacteria caused by antibiotic residues in the environment has become one of the hot issues in the world.So,it is of great significance to investigate antibiotics residue and pollution characteristics.In China,some studies have focused on several major rivers,and researches on northwestern aquatic system is relatively rare.In this paper,the distribution characteristics of antibiotic in Weihe River,the maximum tributary of the Yellow River--was studied.Antibiotics residual concentrations and distribution trends,sources and ecological risks in Xi’an section of Weihe river were investigated.The main researches are as follows:(1)In spring,15 kinds of antibiotics were detected in the water samples,with the concentration in range of nd～276.6 ng/L.The concentration of dehydrated erythromycin(ETM)was the highest(83.99 ng/L).The total antibiotic concentration was the highest in the sampling sites of G1 and G2,which belongs to Lintong and Gaoling regions.In autumn,besides the above 15 kinds of antibiotics,sulfamethoxypyridazine was detected as well.The total antibiotics residue concentration was in range of nd～1251.92 ng/L,oxytetracycline(OTC)was the highest,with the average concentration of 430 ng/L.14 kinds of antibiotics were detected in the main tributaries and the two wastewater treatment plants close to Weihe River in autumn,,with the total concentration of nd～1119.94 ng/L.Lincomycin residue was the highest,with its average concentration of 259.08 ng/L.Compared with that in the other the tributaries Jinghe,Bahe,Fenghe and Chanhe,the highest antibiotics residue was detected in Zaohe River,with the concentration in range of 1.61-273.06 ng/L.As to the antitiotics residue in the two wastewater treatment plants,higher residue was detected in Lintong New area sewage treatment Plantthan that in Xi’an No.4 sewage treatment plant with the concentration of nd～1119.94 ng/L.(2)Antibiotics distribution characteristics in the two seasons were compared.In spring and autumn,sulfa antibiotics average concentrations were 871.61 ng/L and 792.33 ng/L respectively.Quinolones concentration were 42.61 ng/L and 34.09 ng/L,and macrolides were 298.11 ng/L and 326.94 ng/L,tetracycline classes were 205.25 ng/L and 191.25 ng/L,linoleamide classes were 23.81 ng/L and 23.91 ng/L.Except macrolides and linoleamide antibiotics,other antibiotics concentration in autumn were greater than that in the spring.(3)The concentration of dehydrated erythromycin(ETM)and total nitrogen(TN),the concentration of ciprofloxacin(CFX)and the concentration of clarithromycin(CTM)were significantly correlated with the values of ammonia nitrogen(NH3-N).The antibiotics concentration was predicted using dilution coefficient,and the results indicated that measured value was much higher than the predicted value.The source of antibiotic was analyzed by principal component analysis combined with multiple linear regression,and the results showed that domestic wastewater,livestock farming,aquaculture wastewater.wastewater and pharmaceutical wastewater tributary import and other types of pollution contributed to antibiotic residues in Weihe River xian section,the sewage made up the highest share of 34%.,.(4)Antibiotics risk was assessed using the risk quotient(RQs),and the results showed that ciprofloxacin,ofloxacin and sulfamethoxazole showed high risk(RQs>1).Norfloxacin,doxycycline and roxithromycin exhibited moderate ecological risk(0.1<RQs<1)in the main stream of Weihe rivere.While ciprofloxacin,ofloxacin and sulfamethoxazole showed high risk,and norfloxacin and roxithromycin showed moderate risk in weihe’s maintributary were shown as high risk,andThe research results of this paper are of great scientific value for new pollutants treatment and the comprehensive restoration of Weihe River. |
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