Study On Accumulation And Dissipation Of Typical Antibiotics In Chicken Manure And Its Control In Vegetable

Veterinary antibiotics not only can effectively control animal diseases,but also can be used as feed additives to promote animal growth.The abuse of veterinary antibiotics in livestock and poultry breeding industry leads to a large number of livestock manure containing antibiotics entering the farmland soil,and then through the absorption of agricultural products such as vegetables and finally through the food chain into the human body,which has potential risks to human health and ecological environment.In this study,tetracycline,oxytetracycline,sulfamethazine and sulfamethoxazole,which are widely used in aquaculture,were used as target antibiotics.Pot experiments were conducted to study the accumulation and dissipation of four antibiotics in chicken manure and how to prevent antibiotics from entering cabbage.In this study,the determination methods of four antibiotics in chicken manure,cabbage and soil were optimized firstly,and then five inhibitors including wheat straw charcoal,rice husk charcoal,montmorillonite,illite and sepiolite were determined by static adsorption experiment.On this basis,the accumulation dynamics of different types and concentrations of antibiotics in chicken manure in cabbage and their effects on the growth of cabbage were studied through soil pot experiment.The effects of five inhibitors on the accumulation of four antibiotics in chicken manure were investigated,and the inhibition mechanism of inhibitors on the absorption of antibiotics in chicken manureby cabbage was analyzed and discussed.At the same time,the effects of inhibitors on photosynthesis of vegetables were also investigated.The main research results are as follows:1.The extraction and purification methods of four antibiotics in chicken manure,cabbage and soil were optimized by standard addition recovery experiment.Sulfonamide antibiotics in three matrices were extracted with extractant A（Na₂EDTA+phosphate buffer+acetonitrile+Na Cl）,tetracycline antibiotics in three matrices were extracted with extractant B（0.1 mol/L Na₂EDTA-Mcllvaine:methanol=1:1）.The extracts were purified using PSA,C₁₈and Mg SO₄,and then UPLC-MS/MS was used for determination.The recoveries of SMZ,SM₂,TC and OTC were73.08%-115.17%,68.93%-116.83%and 74.38%-119.62%,The method limits the ratio of 4 antibiotics in green vegetables to 15.7-17.5 ng/kg,and the ratio of 4antibiotics in soil to 0.5 ng/kg-264.7 ng/kg.The ratio of 4 antibiotics in chicken manure is limited to 2.31 ng/kg-11.53 ng/kg,and the method is accurate and precise,and the detection limit is low,and can be used to determine the residue of 4 antibiotics in chicken manure,vegetables and soil.2.Static adsorption experiments showed that among the 8 adsorbents for testing,rice shell charcoal and wheat straw charcoal had better adsorption effect on sulfonamide and teratomide antibiotics,and its saturation capacity was 312.5mg/g-476.19 mg/g Between 51 mg/g-72.46 mg/g,the adsorption effect of teratin is better,the adsorption capacity is 270.27 mg/g-416.67 mg/g,so it is determined that wheat straw carbon,rice shell carbon,monastic stone,sea bubble stone,yili stone 5kinds of adsorption agent for potted experiments.3.Pot experiments were conducted to study the accumulation and dissipation of four antibiotics in chicken manure in Chinese cabbage.The accumulation period of four kinds of antibiotics in Chinese cabbage was between 0 d and 10 d after transplanting.The accumulation concentration of four kinds of antibiotics in Chinese cabbage reached the highest on the 10th dayand began to decline slowly after 10 d,and began to flatten on the 24th day.The enrichment ability of different antibiotics in Chinese cabbages was also different.Under the same spiked concentration of antibiotics in chicken manure,the accumulation concentration of SM₂was the highest,followed by OTC and TC,and the accumulation concentration of SMZ was the lowest.The higher the concentration of antibiotics in chicken manure,the higher the concentration of antibiotics in Chinese cabbage.4.Pollution control experiments showed that the accumulation concentrations of four antibiotics in Chinese cabbage decreased after adding five kinds of inhibitors to chicken manure,but the inhibitory effects of each inhibitor on different antibiotics were different.The inhibitory effects of montmorillonite and sepiolite on SMZ were weak.The inhibitory effects of five kinds of inhibitors on SM₂were not significantly different,and the inhibitory effect of montmorillonite on TC was also poor.For OTC,the inhibitory effects of wheat straw charcoal and rice husk charcoal were the best,followed by sepiolite and illite,and montmorillonite was the worst.In summary,wheat straw charcoal and rice husk charcoal had good inhibitory effects on four antibiotics accumulation in Chinese cabbage,followed by illite and sepiolite,and montmorillonite was the worst.Compared with the control without inhibitor,the net photosynthetic rate,stomatal conductance and transpiration rate of plants increased,and the intercellular carbon dioxide concentration decreased after adding inhibitor in chicken manure.The inhibitor can reduce the adverse effect of antibiotics on photosynthesis of Chinese cabbage.5.The detection of the effective concentration of antibiotics in soil showed that the decrease of the effective concentration of antibiotics in soil caused by adding inhibitors was one of the main reasons for the decrease of the concentration of antibiotics enriched in Chinese cabbage.The vertical distribution of antibiotics in potted soil showed that the adsorption of inhibitors on antibiotics prevented the downward migration of antibiotics,resulting in the lower concentration of antibiotics than that in the control without inhibitors.This may also be one of the reasons for the concentration decrease of antibiotics in Chinese cabbage.By measuring the microbial diversity of rhizosphere soil of potted cabbage with inhibitors,it was found that the relative abundance of microorganisms changed on day 0 compared with 10th day and24th day,and the relative abundance of antibiotic-resistant bacteria decreased with the increase of days.This may also be one of the reasons for lower concentrations of antibiotics accumulated in Chinese cabbage.