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抗生素被广泛应用于人类和动物的疾病治疗或生长促进,其中环丙沙星(Ciprofloxacin(CIP),C17H18FN3O3)是一种氟喹诺酮类抗生素,结构复杂、残留时间长、污染范围广、易促进抗生素耐药基因的生长,在水环境中被频繁检出,质量浓度一般在ng·L−1到μg·L−1之间[1]。磺胺甲恶唑(Sulfamethoxazole (SMX),C10H11N3O3S)具有很强的抗菌能力和抗菌广谱性,广泛用于治疗人类及动物的细菌感染,但在使用过程中大部分SMX无法被利用,而是以母体化合物或活性代谢物的形式残留在尿液、粪便及废弃饲料中,最终进入地表水或地下水[2]。水环境中残留的抗生素不仅对微生物、植物和脊椎动物具有毒性作用[3],也极有可能诱发抗生素抗性基因的产生,而抗性基因则会通过水平基因转移促进抗生素抗性细菌和其他细菌的传播,对生态环境和人类健康造成巨大威胁[4]。因此,实现水环境中残留抗生素的有效降解对水环境安全保障具有重要意义。
相对于高级氧化、膜过滤和活性炭吸附等抗生素处理技术而言,人工湿地具有成本低、易管理、效果较好等优点[5],被广泛应用于抗生素降解。例如覃岚倩等[6]在水力负荷0.16 m3·(m2·d)−1的条件下,研究了不同粒径砾石填充对抗生素复合污染的净化效果,采用渐变粒径多层填充的方式能够提高人工湿地对氟喹诺酮类、磺胺噻唑、磺胺二甲基嘧啶和氧四环素的去除效果。刘佳等[7]在水力停留时间为1~4 d的条件下,研究了水平潜流和下行-上行复合垂直流人工湿地对恩诺沙星、磺胺甲唑和氟甲砜霉素的去除效果,结果发现人工湿地构型对抗生素的去除效果差异不大,而延长水力停留可显著提高湿地对抗生素的去除效果。人工湿地在去除抗生素的同时,湿地内植物、微生物也会受到抗生素的影响而发生性状的改变,进而影响人工湿地中污染物的降解过程[8-9],理解这些变化过程对改善人工湿地对抗生素的去除具有重要意义。有研究[6]表明,添加抗生素后促进人工湿地内变形菌门、厚壁菌门、浮霉菌门相对丰度的上升,而磺胺嘧啶则会降低污水处理系统的氨氮和总氮去除能力[10]。然而,目前对多种类抗生素胁迫下人工湿地中植物生理特性及微生物群落响应的研究却较少。针对多种类抗生素胁迫下湿地植物生理和微生物群落的变化特征,构建了2组上向垂直流人工湿地,选取磺胺甲恶唑和环丙沙星为典型抗生素,探究多种类抗生素存在下人工湿地的污染物去除效能,及植物和微生物特性的改变规律,以期为提高人工湿地的水质安全保障功能提供支撑。
多种类抗生素对垂直流人工湿地净化作用的影响机制
The influence mechanism of multiple antibiotics on the purification efficiency of vertical flow constructed wetlands
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摘要: 针对抗生素残留造成的水环境安全问题,以提升人工湿地的水质安全保障功能为目的,研究抗生素对人工湿地净化功能的影响机制。通过构建添加抗生素组上向垂直流人工湿地(CW-A)和对照组人工湿地(CW),研究多类别抗生素在人工湿地中的去除特点及其对人工湿地污染物去除效果、植物生长特性,微生物群落组成的影响作用。结果表明,人工湿地对环丙沙星(CIP)的去除率为96.03%,显著高于对磺胺甲恶唑(SMX) (76.70%)。CIP与SMX的加入对人工湿地的COD和TP去除效果没有显著影响(89.55%、86.53%和47.59%、50.39%,P > 0.05)。抗生素对湿地植物细胞产生了一定程度的破坏,导致CW-A中植物的生物量相对CW中植物减少了20.63%;高通量测序结果表明,抗生素降低人工湿地中脱氮功能菌属Chlorobaculum、Zoogloea、Pseudomonas和Acinetobacter的相对丰度,并显著影响了CW-A的TN去除效果,使其去除率(34.82%)显著低于CW(40.72%,P<0.05)。Abstract: Aiming at the water environment safety problems caused by antibiotics, improving the water quality safety guarantee function of constructed wetland, the effect of antibiotics on the purification capacity of it was studied. Constructing the up-vertical flow constructed wetland added antibiotics (CW-A) and the control constructed wetland without antibiotics addition (CW), the removal characteristics of multiple antibiotics and their effects on pollutant removal, plant growth characteristics and microbial community composition of constructed wetland were studied. The results showed that the removal rate of ciprofloxacin (CIP) was 96.03%, significant higher than that of sulfamethoxazole (SMX) (76.70%). CIP and SMX had no significant effect on COD and TP removal in constructed wetland (89.55% , 86.53% and 47.59% , 50.39%, P>0.05). Antibiotics caused damage to plant cells, resulting in a 20.63% reduction in biomass of plants in CW-A compared with plants in CW. High-throughput sequencing results showed that antibiotics could reduce the relative abundance of Chlorobaculum, Zoogloea, Pseudomonas and Acinetobacter in constructed wetland, resulting in a significantly lower TN removal rate in CW-A (34.82%) compared to CW (40.72%, P<0.05).
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Key words:
- constructed wetland /
- sulfamethoxazole /
- ciprofloxacin /
- plants /
- microbial community
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表 1 抗生素添加组和未添加组进水水质
Table 1. Water quality of the antibiotic-added and non-added groups mg·L−1
类别 COD TN NH4+-N NO3−-N TP CW-A 609.09±11.91 31.66±1.47 29.3±1.26 0.91±0.32 4.59±0.34 CW 571.77±19.32 30.99±1.57 30.16±1.66 0.78±0.23 4.74±0.37 表 2 人工湿地中微生物种群丰度和多样性分析
Table 2. Analysis of microbial population abundance and diversity in the constructed wetlands
样本 序列数 OTUs Ace Chao1 覆盖率/% Simpson Shannon CW 24 947 715 1 244.51 1 045.53 98.96 0.099 4.53 CW-A 24 333 976 1 390.38 1 299.22 98.87 0.074 4.01 -
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