| China is a big country for livestock and poultry breeding.In the process of livestock and poultry breeding,Sulfonamides(SAs)are widely used in the prevention and treatment of bacterial diseases because of their low price and good therapeutic effect.At the same time,the farm emits a large amount of aquaculture wastewater with high organic concentration,complex composition and antibiotic components.For the treatment of aquaculture wastewater,major domestic and international research focus on COD,total nitrogen,ammonia nitrogen,total phosphorus,phosphate and other conventional parameters,and few research focus on the characteristics of antibiotics in the migration,depletion and distribution of aquaculture wastewater and sediment,and the effects of sulfa antibiotics on fish tissue enrichment in wastewater and food safety.Therefore,a typical "pig-fish" ecological farm in Longyan,Fujian Province was selected as the research object,and the residual characteristics of SAs was analyzed,the removal and distribution of SAs were discussed in aquaculture wastewater,sediment and farm soil,SAs content was compared in fish tissues(gill,skin,muscle and hepatopancreas),and the food safety of farmed fish was evaluated.On the other hand,after a single oral irrigation of 150 mg/kg sulfamethoxazole,a pharmacokinetic model of SMZ in carp was established.The correlation between the changes of drug residues in various tissues and the effects on superoxide dismutase(SOD)and catalase(CAT)were discussed.Combining the Maximum Residue Limit(MRL)and antioxidant enzyme activity,the rationality of using the enzyme activity to formulate the drug withdrawal period was discussed.Finally,the distribution of SAs in the "pig-fish" eco-culture system and the pharmacokinetic model of SMZ in different tissues of fish were established.Combining the real environment on site with experimental simulation conditions,we analyzed the overall migration,transformation and distribution of SAs in the external environment and organisms during livestock and poultry farming.The main conclusions are showed as follows:(1)High performance liquid chromatography-ultraviolet detection method for SAs was established in fish tissues,soil(sediment)and water.Acetonitrile/dichloromethane and EDTA-Mcllvaine(pH=4)-methanol(1:1,V/V)was used to extract SAs from fish tissues and soil.Fish tissue samples were purified by 1%formic acid-methanol(67+33).Solid phase extraction was performed[fish tissue sample and water extraction cartridge(HLB);soil and sediment extraction cartridge(Cleanert SAX-HLB in series)],and carried out nitrogen blowing and reconstitution.The sample was separated by waters Symmetry C18 at 30℃ for 1 mL/min under the conditions of chromatographic pure acetonitrile and 0.1%aqueous formic acid.The detection limit was 2.75～5.85 ng/mL.The limit of quantification was 9.17～19.22 ng/mL,and the average recovery was 70.08～94.04%,and the relative standard deviation was 0.70～12.05%.(2)The removal rate and migration of SAs in the wastewater of "pig-fish" ecological aquaculture system were studied.After precipitation,CMIC composite immobilization carrier biotechnology combined with anaerobic treatment,post-stage oxidation pond,and staged filtration treatment,the concentration of ∑ SAs decreased to 1.29μg/L at the final outlet.The total removal rate of SAs reached over 91.28%,and the effect was remarkable.However,SAs tends to be adsorbed to suspended solids(SS)or organic matter precipitates with gravity during the removal process,therefore,SAs conc.in sediment content increased.(3)Sulfadiazine(SD),sulfamethoxazole(SMZ),sulfisoxazole(SIZ),and Sulfadimethoxypyrimidine(SDM)were detected in the cultured fish tissues.The total concentration of SAs residues are:kidney>hepatopancreas>gill>skin>muscle.Antibiotic residue(dissolved in water and adsorbed to SS and organic matter)and feeded medicine(indirectly added feed or direct drug feeding)are the main source of SAs in fish tissue.In fish tissues,except for the total concentration of SAs in the kidney exceeding the MRL(100 μg/kg),other tissues did not exceed.According to dietary safety evaluation results,muscle,hepatopancreas as materials.Because the total SAs dietary intake only accounted for 0.049%,0.009%of the allowable daily intake(ADI)limit(<1%ADI),its health risks are negligible.After a single dose of squid(150 mg/kg),SMZ showed a highly positive correlation with the tissue concentration of SMZ in fish(r=0.892～0.955,P<0.01).We can analyze the concentration of a single tissue drug residue to assess the overall drug residue level and judge the safety of the food.Firstly,using SOD and CAT determined the drug withdrawal period.① After taking the medicine for 1～2d,the food safety of fish is subject to drug assessment;After feeding for some days,enzyme activity analysis can be used.When the difference from edible fish is not significant,it can be preliminarily determined to be edible;When the difference is significant,the drug residue concentration needs to be analyzed again for food safety.②After taking the medicine for 4～26d,The concentration of SMZ in the edible tissue was highly positively correlated with the activity of SOD in hepatopancreas.(r=0.794、0.798,P<0.01).Because the concentration of SMZ is poorly correlated with CAT activity in hepatopancreas,it is recommended to avoid using CAT enzyme alone to determine whether it is safe to eat or not. |
PDF Full Text Request