Pollution Characteristics And Risk Assessment Of Tetracycline Antibiotics In Peri-urban Vegetable Soils Collected From Northern Guangzhou City

Antibiotics were widely used as growth promoting agents and antibacterial agents for the prevention and treatment of human and livestock disease.However,30-90% of these antibacterial agents could not be absorbed by the body.They would be discharged with feces,in form of the drug solution or its metabolites and entered into the soil and other environmentwith livestock and poultry manure.At present,the relevant institutions certification of vegetable base such as the the green vegetable base and organic vegetable base,emphasized the use of manure compost organic fertilizer,which would inevitably cause the accumulation and pollution of antibiotics in soils.Pollutionof antibiotics in the vegetable basecould not only damage the structure and function of microbial communities in soils,but aslo be absorbed and accumulated by crops,thereby,endanger human health through the food chain.Meanwhile,antibiotic could cause water pollution by leaching,runoff and so on,which were toxic to aquatic organisms andso on,which were toxic to aquatic organisms.Therefore,investigating the characteristics of antibiotic pollution of vegetable and establishing a regional risk assessment system has become one of the focuses of environmental scientists.We explored the residual status of three kinds of tetracycline antibiotics(tetracycline,oxytetracycline,chlortetracycline TC;OTC;and C TC)in soil samples in 20 vegetable bases which were located in the northern suburb of Guangzhou,by solid phase extraction(SPE)and high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS).We analyzed the main sources of soil antibiotics by analytic hierarchy process,obtained the soil water partition coefficient(Kd)and adsorption capacity inthree kinds of antibiotics by the adsorption desorption kinetics experiment,obtained the predicted ineffective concentration in water by establishing species sensitivity distribution.Then we estimated the effective concentration in soil by the phase equilibrium method and evaluatedthe ecological risk of antibiotics to edaphon and plant by the risk quotient method.Finally we evaluated the ecological risk assessment of the three tetracyclines Kriging interpolation by the Arcgis software.The results were showed as follow,(1)The results showed that the concentrations of TC,OTC and CTC ranged between ND-30.37 ?g/kg,ND-903.13 ?g/kg and ND-103.02 ?g/kg,respectively.The mean values were 5.64 ?g/kg for TC,38.39 ?g/kg for OTC,and 8.92 ?g/kg for CTC,which indicating they were in the following order: O TC > CTC> TC.TCs source identification indicated that applying manure was the principle source of TCs in vegetable soils in the study area,accounting for more than 50%,followed by applying commercial organic fertilizers,accounting about 24%.(2)Dose-effect evaluation results showed that the three kinds of tetracycline antibiotics in the same concentration had different effects on edaphonand plant,which was ranked as TC>CTC>OTC.(3)The results of riskquotient showed that the ecological risk of the three kinds of TCs in soils was in the middle of the whole risk.However,the southwest region of the study area was at high risk,whose main pollutants were TC,followed by OTC.