垂直流-水平潜流组合湿地对磺胺类抗生素的去除

Effect of the vertical and horizontal subsurface-flow resultant wetland on the removal of the sulfonamide antibiotics

利用垂直流串联水平潜流的组合人工湿地处理污水处理厂尾水，比较有植物和无植物组合湿地对磺胺类抗生素母体及N 4 乙酰代谢物的去除效果。结果表明：有植物组合湿地的去除效率为72.31%，高于无植物组合湿地的59.71%；不同种类湿地植物对磺胺类抗生素的吸收累积能力存在差异，美人蕉积累量最大，其次为风车草，花叶芦竹最低；植物各部位对磺胺类抗生素的积累为地下组织（根）大于地上组织（叶和茎）；基质对磺胺类抗生素的吸附能力表现为有植物基质吸附量大于无植物基质，变化范围为0.34-1.59 ng/g dw，表明湿地植物的存在更有利于磺胺类抗生素的降解。垂直流-潜流组合湿地能较好地降解磺胺类抗生素，但其降解机理及植物在其中的作用有待进一步研究。

The paper is aimed at investigating the removal efficiency of the sulfonamide antibiotics and their acetylated metabolites in the various wetland configurative environments （vertical-, horizontal-, and hybrid-flow, planted or unplanted environments） after the sewage treatment. The application of the HPLC-MS/MS has enabled us to find that the concentration of the acetylated metabolites tends to be 1.76 to 6.55 times as high as that of the parent sulfonamide, though it is possible for the metabolite removal efficiency to be higher than that of the antibiotics, including the partial re-conversion to the parent sulfonamide. What is more, it is possible to achieve the finest approximation of the removal efficiency by combining the values for both the parent sulfonamide and the metabolite itself, which can help to reach the efficiencies of 72.31% and 59.71% both for the planted and unplanted wetlands. At the same time, the antibiotic content in the substrate turns out to be the dry weight of 0.34-1.59 ng/g, which tends to be actually much higher in the planted than in the unplanted hybrid wetland. In addition, we have also detected there exist sulfonamide antibiotics in the surface-ground and underground tissues, such as in Canna indica, Cyperus alternifolius, and Arundo donax, with accumulations of their tissue distribution in a descending order： underground tissues 〉 surface-ground tissues. However, no much effect of the construction of the vertical-flow wetland has been found on the wetland plants, when the removal efficiencies of 67.06% and 64.80% for the planted and unplanted configurations, respectively. Besides, the removal efficiency of the planted horizontal subsurface-flow constructed wetland （15.95%） proves to be higher than that of the unplanted one （-14.46%）. Thus, the wetland-based sulfonamide antibiotic degradation should be mainly attributed to the aerobic one. As to the effect of plants, especially, of the root system, on the vertical-flow constructed wetland, it has proved to result in a higher content of antibiotics in the upper area than in the lower one. Nevertheless, for the horizontal-flow constructed wetlands, the influent region may have higher values than the effluent one, though the antibiotics accumulation by the wetland plants and substrates proves to contribute little to the reduction of the wetland pollutant load. And, finally, it is necessary to point out that further research is needed for the environmental behaviors of sulfonamide antibiotics in the constructed wetlands, especially, the microbial degradation processes.