摘要
      残留抗生素的排放已经造成了环境危害。研究了典型四环素类抗生素（土霉素和四环素）在垂直流人工湿地（VFCWs）中对ZnFe层状双氢氧化物（ZnFe-LDHs）修饰基质的去除性能以及4个相应的抗生素抗性基因（ARGs）的影响。表征试验表明，ZnFe-LDH成功地涂覆在牡蛎壳上，并增加了改性牡蛎壳的比表面积和原子种类。吸附实验表明，土霉素和四环素在ZnFe-LDHs中的最高饱和吸附量分别达到1171.51和2035.25mg/kg，高于砾石和牡蛎壳（分别为264.37和353.74mg/kg）。CWs实验表明，改良牡蛎壳和人工球体系统对土霉素和四环素的平均去除率分别为87.27%、86.55%和71.94%、74.09%，显著优于砾石系统（45.57%和39.3%）和牡蛎壳系统（59.79%和54.86%），修饰体系中的微生物ASV/OTUs数量和四个抗性基因的总相对丰度（0.315和0.228）低于天然体系中的（0.237和0.427）。这些结果表明，ZnFe-LDHs涂层显著影响了微生物活性，减少了ARGs的积累。ARGs与常规污染物之间的相关性分析表明，营养物质可能会影响ARGs在CWs中的传播。总之，ZnFe-LDHs修饰的底物可以显著提高四环素和土霉素的去除效率，并影响氮的生物降解，而由于营养物质的存在，ARGs仍可能在系统中积累。
Abstract
The emission of residual antibiotics has already caused environmental hazards. The removal performance of typical tetracyclines antibiotics (oxytetracycline and tetracycline) and the effect of 4 corresponding antibiotic resistance genes (ARGs) were investigated in vertical flow constructed wetlands (VFCWs) with ZnFe-layered double hydroxides (ZnFe-LDHs) modified substrates. The characterizations tests exhibited ZnFe-LDHs were successfully coated to the oyster shell, and increased the specific surface area and atomic species of the modified oyster shell. Adsorption experiments showed that the highest saturated adsorption capacity of oxytetracycline and tetracycline in ZnFe-LDHs respectively reached 1171.51 and 2035.25 mg/kg, which was higher than those of the gravel and oyster shell (264.37 and 353.74 mg/kg, respectively). The CWs experiment indicated that the average removal rates of oxytetracycline and tetracycline in modified oyster shell and artificial sphere systems were respectively 87.27%, 86.55% and 71.94%, 74.09%, which was significantly superior to the gravel (45.57% and 39.3%) and oyster shell systems (59.79% and 54.86%). Moreover, the microbial ASVs/OTUs numbers and the total relative abundance of four resistance genes in the modified systems (0.315 and 0.228) were lower than those in natural systems (0.237 and 0.427). These results suggested that ZnFe-LDHs coating significantly affected microbial activity and reduced the accumulation of ARGs. Correlation analysis between ARGs and conventional pollutants exhibited that nutrient might affect the spread of ARGs in CWs. In summary, ZnFe-LDHs modified substrates could significantly improve the removal efficiency of tetracycline and oxytetracycline, and affected the N biodegradation, while ARGs might still accumulate in the systems due to the presence of nutrients.

https://www.sciencedirect.com/science/article/abs/pii/S1385894721056679