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研究论文

Effects of biochars on the dissipation and potential risk of antibiotics in an agricultural soil

摘要：本研究采用农业废弃物玉米轴、玉米秸秆和核桃壳分别于250、400和600℃下缺氧热解制备生物质炭，并通过土壤培养实验考察了生物质炭对灭菌和未灭菌农田土壤中四环素类、磺胺类和喹诺酮类抗生素消减和潜在风险的影响.对照和生物质炭处理组均是未灭菌土壤中抗生素的消减率通常高于灭菌土壤，这是因为灭菌土壤中的抗生素以非生物消减为主，而未灭菌土壤中同时存在抗生素的非生物消减和微生物降解.250℃制备的核桃壳生物质炭促进了灭菌和未灭菌土壤中抗生素的消减.灭菌和未灭菌土壤中抗生素表观分配系数（K_app）变化趋势均是喹诺酮类>四环素类>磺胺类.与灭菌土壤相比，未灭菌土壤中抗生素的K_app值通常较低，说明微生物可以促进土壤中抗生素从轻结合态甚至紧密结合态向着交换态或者水溶态转变.多数生物质炭降低了灭菌和未灭菌土壤中四环素类和喹诺酮类的K_app值，这将增大抗生素的迁移性和传播抗性基因的风险.

Abstract：Three types of biochars were prepared by anoxic pyrolysis at 250, 400, and 600℃ using corn cob, corn straw and walnut shell. The effect of these biochars on the reducing the potential risk of tetracycline, sulfonamide and quinolone antibiotics in sterilized and unsterilized farmland soil was investigated through soil culture experiment. Compared to those in the sterilized soils in where abiotic degradation only occurs, the higher removal rates of antibiotics were obtained in the unsterilized soil contributed by the both biotic and abiotic degradation in the soil. Walnut shell-derived biochar prepared at 250℃ promoted the dissipation of the antibiotics in the sterilized and unsterilized soils. In both the sterilized and unsterilized soils, the apparent distribution coefficient (K_app) of antibiotics followed the order:quinolones>tetracyclines>sulfonamides. Compared with the sterilized soil, the lower K_app values of all three types of antibiotics were found in the unsterilized soil, indicating that microorganisms promoted the conversion of antibiotics from loosely bound or even tightly bound fractions to exchangeable or water soluble fractions. Most biochars decreased K_app values of tetracyclines and quinolones, which would increase the mobility of antibiotics and the risk of spreading resistance genes.