Combined Pollution Characteristics And Preliminary Risk Assessment Of Veterinary Drugs In Drinking Water Sources In Fujian Province

With the increasing demand for animal foodstuff caused by population increasing and living standards improving in our country,the scale of livestock agriculture and aquaculture are rapidly expanding and the categories,production and usage of veterinary drugs are also dramatically increasing.Veterinary drugs enter into the aquatic environment in various forms and through various ways.Surface waters,such as rivers,lakes and reservoirs,are the main drinking water sources for cities.Therefore,it is of great significance to study the combined pollution and risk status of veterinary drugs residue in drinking water sources.In this paper,a sensitive and reliable simultaneous determination method for 137 veterinary drugs of 25 classes was established,and successfully applied for the pullution survey of Jiulongjiang River,Jinjiang River,Minjiang River in Fujian Province.The combined pulluion characteristics and risk assessment of veterinary drugs were studied.The results are as follows:1.Establishment of simultaneous detection method for 137 target veterinary drugs by liquid chromatography coupled to triple quadrupole mass spectrometry.In this study,LC-MS/MS spectrometry parameters(parent ions,daughter ions and collision energy)under ESI ionization and MRM acquisition modes,as well as chromatographic separation conditions such as elution procedures and reconstitution solvents were optimized.Good linearities of 137 target veterinary drugs were obtained within a certain concentration range(R2≥0.9910),and the instrumental detection limits were between 0.001 μg/L and 5 μg/L,which meets the sensitivity requirements of target veterinary drug detection.The pretreatment conditions including filter selection,SPE elution and rinse solvent,pH of water sample and Na2EDTA addition amount were investigated.The quantitative methods of external standard calibration,isotope-labelled surrogates method,and matrix matched calibration method were evaluated.At 5 ng/L,20 ng/L and 100 ng/L spiking levels,the recoveries of 87.6%,92.7%and 94.2%of the target veterinary drugs were between 40%-130%with relative standard deviations(n=4)in the range of 0.2%-26.5%,0.8%-27.6%and 0.3%-23.6%,respectively,except for albendazole,spiramycin,estriol,clorsulon,and analgin.97.8%of the target veterinary drugs method detection limits(MDLs)were 0.01-3.0 ng/L and the method quantitative limits(MQLs)were 0.05-10.0 ng/L.The proposed methods could meet the determination requirements for trace multi-veterinary drugs in drinking water source.2.Study of combined pollution characteristics of veterinary drugs in drinking water sources in Fujian Province.The established methods were applied to the monitoring of 137 target veterinary drugs in surface water samples collected in 55 stations form Jiulongjiang River,Jinjiang River and Minjiang River in May,October and November,2018.The results showed that the detected veterinary drugs and the total amount in each station in Jiulongjiang River,Jinjiang River and Minjiang River were 12 classes of 32 drugs(4.9-1595.0 ng/L),9 classes of 24 drugs(61.6-274.0 ng/L)and 12 classes of 26 drugs(135.7-797.2 ng/L),respectively.On the whole,chloramphenicol,sulfonamides,macrolides,anti-insect drugs and amantadine are main detected categories in 3 rivers.Among them,sulfamethoxazole,amantadine and florfenicol are the main pollutants in Jiulongjiang River,amantadine,chlortetracycline and amprolium in Jinjiang River and salinomycin,sulfamethoxazole,florfenicol in Minjiang River.3.Safety and risk assessment of veterinary drugs in Jiulongjiang River,Jinjiang River and Minjiang River.The safety risks of veterinary drugs residue in drinking water sources are difficult to evaluate due to the lack of standard limits.The ecological risk of detected veterinary drugs residue in Jiulongjiang River,Jinjiang River and Minjiang River were assessed using risk quotient method.Results showed that sulfonamides,macrolides and quinolones contribute higher ecological risk in Jiulongjiang River,quinolones,macrolides,sulfonamides in Jinjiang River and sulfonamides,macrolides,tetracyclines in Minjiang River.Sulfamethoxazole,sulfadiazine,erythromycin and lincomycin are the main risk spices in the three major waters.This study provide a reliable technique for the monitoring of various veterinary drugs in aquatic environment,and scientific data for risk assessment and veterinary drug m anagement.