Pollution Level,Source And Ecological Risk Of Typical Antibiotics In The Dongting Lake,China

Antibiotics,as a class of pharmaceuticals that are extensively used worldwide,had raised significant concerns of the environmental sciences,toxicology and epidemiology in recent decades for their potential threat to ecological environment and human health.With economic development and population growth,large does of antibiotics are using each year in China.As an important antibiotics consumption and production nation,antibiotic contamination in the water environment in China is very serious.Dongting Lake,as a important role in water supply for fisheries,livestock and poultry,would be subject to a certain degree of antibiotic contamination.However,limited studies have concentrated on the antibiotic pollution level,sources and its ecological risk in Dongting Lake.Therefore,12 antibiotics belonging to four classes were selected as target compounds and samples in the state-controlled section and provincial-controlled section were collected,in order to study systematically pollution level,source and ecological risk tentatively in water,sediment and fish in the Dongting Lake.The main results obtained were summarized as fo1lows:(1)The extraction method of 12 antibiotic enrichment including sulfanilamides(SAs),trimethoprim(TMP),quinolones(QNs)and tetracyclines(TCs)in water,sediment and fish sample were optimized.The results of the accuracy of methods tested indicated that the proposed method can meet the requirement of antibiotic determination in water,sediment and fish sample.(2)The antibiotic concentration in water on dry and wet season were respectively in the range of ND~61.28ng·L-1 and ND~8.73ng·L-1,with total concentration of6.35~135.40 ng·L-1 and 1.06~17.42 ng·L-1.The highest average concentration was sulfadiazine,with the detection frequency of more than 60%.The total concentrations of antibiotics were higher in Nandu,Zhangshugang,Bianshan,East Dongting Lake and Yugongmiao.The pollution level in spatially showed obvious difference,whichwas East Dongting Lake>South Dongting Lake>West Dongting Lake which was closely related to the distribution and scales of aquaculture,livestock and poultry.In addition,the occurrence characteristics of antibiotics in water could be affected by Chla,CODmn,TN,etc.The antibiotic concentration in sediment on wet season ranged from ND to 5.56 ng·g-1.Sulfadiazine(SDZ),enrofloxacin(ENR),chlortetracycline(CTC)and Tetracycline(TC)were the main pollutants in sediment.In spatially,the pollution level of antibiotic was similar to water.The occurrence characteristics of antibiotics in sediment could be affected by ps,pb,etc.The concentration level of antibiotics in fish was in the range of ND~1.06 ng·g-1,with higher detection frequency of sulfadiazine(SDZ),enrofloxacin(ENR).The concentration level of antibiotics in the bottom organisms such as silurus asotus,cyprinus carpio and palinuridae were higher.(3)This paper assess the potential ecological risks associated with the antibiotics present by the risk quotient(RQ)method.Due to their trace residue,the RQs for most of antibiotics in water were below 0.1.The the RQs of sulfamethoxazole,ciprofloxacin and sarafloxacin were higher,which indicted they could have a significant environmental risk to the Dongting Lake.The health risk index on dry and wet season were respectively in range of 5.09×10-8~6.94×10-5·a-1 and 1.70×10-8~1.28×10-5·a-1.Among the 10 antibiotics,quinolones were major health risk factors,which was in range of 10-6 ~ 10-5.Compared to adults,the level of health risk to children was higher,which should be paid great attention to.The results of cumulative risk assessment showed that Nandu and Zhangshugang had higher risk.The RQ of 10 antibiotics detected in sediment ranged from 2.07×10-4 to-29.87,which was higher than water environment risk.The ciprofloxacin(CIP)and sarafloxacin(SFLO)were the main risk factor in sediment.The cumulative risk of East Dongting Lake,Bianshan,Mapo Lake,Potou,Xiaohezui and Zhangshugang were higher.The antibiotic residues in fish were mostly below MARLvalues.The RDQ of antibiotics intake by fish to rural residents and townsmen were respectively in range of5.85×10-7 ~ 5.17×10-4 and 1.23×10-6 ~ 1.09×10-3,which enrofloxacin(ENR)andarafloxacin(SFLO)had higher RDQ.The RQfcom of silurus asotus palinuridae had higher potential threat to physical health.(4)Through the investigation of some pollution sources around Dongting Lake,the pollution sources of 12 antibiotics were defined preliminarily.The pollution sources of Sulfadiazine(SDZ),Sulfamethoxazole(SMX),Sulfamethazine(SMZ),Trimethoprim(TMP),Sarafloxacin(SFLO),Chlortetracycline(CTC)were aquaculture,livestock and poultry;The sewage disposal plant was the pollution source of ciprofloxacin(CIP)and oxytetracycline(OTC);Tetracycline(TC),as the important class antibiotics and widely used in many countries worldwide to treat disease and protect the health of animals,was mainly from livestock and poultry;Norfloxacin(NOR)and enrofloxacin(ENR)were mainly from aquaculture source.