The Occurrence Of Typical Antibiotics And Antibiotic Resistance Genes In Paddy Soils With Long-term And Quantitative Manure Application

Antibiotics are commonly used as feed addictives in livestock industry to prevent animal diseases and promote animal growth. However, with large scale use of antibiotics and farmland application of animal excrements, antibiotics which are not absorbed or degraded by animals enter into agricultural soil. Meanwhile, the appearance of antibiotic resistance genes (ARGs) induced by antibiotics residual gradually gains attention in environmental researches. Until now, most studies focused on grab samples and antibiotic analysis, or laboratory microcosm tests, while study on the occurrence of antibiotics and ARGs in paddy soil with long-term manure application is lack. This study chose four long-term field experiment sites in south China, quantified six typical veterinary antibiotics and eight ARGs in surface and profile soils with and without long-term manure application, investigated their pollution characteristics in paddy soil and their correlations. The main conclusions are as follows:(1) Surface paddy soil with long-term manure application had distinct tetracyclines accumulation, and significant enhancement of ARGs, suggesting that long-term manure application would result in antibiotics and ARGs pollution in surface soil.(2) The concentration of antibiotics got higher when manure application amount got larger, and there was a significant correlation between the abundance of ARGs and manure application amount.(3) The concentration of antibiotics and the abundance of ARGs declined with soil getting deeper, indicating that antibiotics and microbes carrying ARGs could transport from surface soil to profile soil.(4) Tetracyclines positively correlated to heavy metals, and there existed correlation between the abundance of ARGs and soil pH, SOM, heavy metals (As, Cd, Cu, Zn), but a poor correlation between ARGs and tetracyclines.