Research On Environmental Behavior And Restoration Of Veterinary Antibiotics From Organic Fertilizer In Two Soils

In order to investigate the influences of antibiotics pollution on the soil environment,it needs to conduct deep and comprehensive research on degrading and transforming the antibiotics in the soil and population structure of soil microbes and metabolic activity,as well as contamination remediation technology.Micocosm incubations were conducted to investigate the degradation and transformation of antibiotic from organic fertilizer containing different doses of sulfonamides,tetracycline or mixture of the two antibiotics(1:1),and their effects on the soil microbial community in two soils(purple clay and silt soils).The preliminary screening of the pollution remediation agent was set up at the same time.The results were as follows:(1)Under the incubation condition,sulfadimidine and doxycycline were decomposed quickly in soils.In different soils,the degradation speed was different and related with the soilproperty.In the silt soil,the degradation of sulfadimidine and doxycycline was relatively faster than that in the purple clay soil,respectively.Before 28 days,the rate of degradation was increased quickly.After 28 days,it had a tendency to be stable.The final degradation rate of the two antibiotics was 93%-97%and 95%-97%,respectively.In the purple clay soil,the upswing process of the rate of degradation was relatively slow.It was not stable till it has been cultivated for 42 days.However,the final degradation rate of the two antibiotics reached 95%-97%and 95%-97%,respectively,which was similar with that in the silt soil.In the preliminary stage of the incubation(on the third day),under combinedpollution of two antibotics,the degradation rate of no matter sulfadimidine or doxycycline in the soil was higher than under the single pollution.Under the co-existing conditions,the two antibiotics presents to promote degradation mutually.With the increasing of cultivation time,the difference was shrinking gradually.(2)After applying sulfadimidine,doxycycline and mixture into the soils,they could stimulate respiration of soil microorganism in the short term,induced the temporary improvement of metabolic diversity of the soil microbial community.However,the effects were decreased with increasing incubation time.The coexistence of sulfadimidine and doxycycline did not show obvious synergistic effect or additive effect on the metabolism of soil microorganism community.Among them,the influence of doxycycline on the metabolism of soil microorganism community was higher than that of sulfadimidine.It was the important driving force for the complicated antibiotics to contaminate the structure of soil microbial community and the changes of diversity.In the purple clay soil,the concentration of doxycycline,with the metabolic activity of microorganism and diversity,presents remarkable positive correlation.The soil microbial metabolism was increased with increasing the concentration of doxycycline,but the silt soil had no similar phenomena.(3)Adding certain allothigene had certain effect on removing residual antibiotics in soil.Among them,the bamboo charcoal,sawdust,white-rot fungus inoculant and OTC-16+SMD-FA inoculant lowered the sulfonamides in the soil by 78%,70%,61%and 54%,compared with the control treatments.OTC-16+SMD-FA microbial inoculum and humic acid materials could apparently remove the residue of the doxycycline in soil.In the soil,the proportions of drug resistant bacteria of different antibiotics contamination were different,among which the proportion of drug resistant bacteria of sulfadimidine was higher than that of doxycycline.The self-made OTC-16+SMD-FA inoculant not only could play the promotion role in degrading sulfadimidine and doxycycline,but also apparently lowered the proportions of two antibiotics resistant bacteria in the soil bacteria and inhibited the spread of drug resistance genes in the soils.