Abstract:

The extensive application of nano-products leads to the wide distribution of nano-particles in different environments, which causes potential ecological risks. Constructed wetland is a sewage ecological treatment system composed of plants, substrates and microorganisms, which inevitably becomes the “sink” of nanoparticles. To compare the ecological effects difference of metal oxide nanoparticles and non-metal oxide nanoparticles on microbial communities in constructed wetlands. The study selected graphene oxide (GO) and copper oxide nanoparticles (CuO NPs) as the objects of the study, and constructed three groups of Iris pseudacorus-constructed wetland ecological treatment systems with vertical flow, including the control group (without nanoparticles), the GO-exposed group and the CuO NPs exposed group. The dynamic response of microbial communities in constructed wetland ecosystems exposed to GO and CuO NPs was investigated. The results of 16S rDNA sequencing showed that the richness and diversity of the microbial community increased under GO and CuO NPs exposure, while the exposure of CuO NPs suppressed the evolutionary diversity of the microbial community. As the dominant phylum, the abundance of Actinobacteria decreased when exposed exposure to pollutants, while the phylum of Proteobacteria showed better adaptability. The microbial community structure responded to different nanoparticle exposures by different mechanisms, e.g., the class of Actinobacteria and Gammaproteobacteria was suppressed by the pollutants in the abundance, while the dominant genus of Mycobacterium was more tolerant to GO exposures and less tolerant to CuO NPs exposures. According to the classification of the KEGG database, Some metabolic pathways of constructed wetlands are weakened after pollutant exposure. It was also found that Carbohydrate metabolism and Amino acid metabolism showed lower abundance in the CuO NPs exposure treatment group. The above results suggest that CuO NPs may be more ecotoxic to constructed wetlands, and the study also provides a new perspective for nanomaterials to affect the ecological functions of constructed wetlands.

Key words: constructed wetland, GO, CuO NPs, microbial community, functional prediction, defense mechanism

摘要：

纳米产品大量应用导致纳米颗粒在不同环境中广泛分布，并引起潜在的生态风险。而人工湿地是由植物-基质-微生物组成的污水生态处理系统，不可避免地成为纳米颗粒这一新型污染物的“汇”。为了对比金属氧化物纳米颗粒与非金属氧化物纳米颗粒在人工湿地中对微生物群落的生态效应差异，选取氧化石墨烯（GO）和纳米氧化铜（CuO NPs）为研究对象，构建3组黄菖蒲垂直流人工湿地生态处理系统，分别设为对照组（不投加纳米颗粒）、GO 暴露组、CuO NPs暴露组，考察GO和CuO NPs暴露下人工湿地生态系统微生物群落的动态响应。通过16S rDNA测序结果表明，GO和CuO NPs暴露下人工湿地微生物群落丰富度和多样性均有所提升，但CuO NPs暴露抑制了微生物群落进化多样性。作为优势菌门，放线菌（Actinobacteria）在受到污染物暴露后丰度降低，而变形菌门（Proteobacteria）表现出较好的适应能力。微生物群落结构针对不同纳米颗粒的暴露响应机制不同，如放线菌纲（Actinobacteria）和γ-变形菌纲（Gammaproteobacteria）丰度均受到污染物抑制，而优势属Mycobacterium对GO暴露具有较强的耐受性，但对CuO NPs暴露具有较低的耐受性。根据KEGG数据库分类同样发现，污染物暴露后的人工湿地部分代谢途径减弱，其中碳水化合物代谢（Carbohydrate metabolism）和氨基酸代谢（Amino acid metabolism）在CuO NPs暴露处理组中表现出更低的丰度。以上结果说明CuO NPs对于人工湿地的生态毒性可能会更强，这为纳米材料影响人工湿地生态功能提供了新的视角。

关键词: 人工湿地, 氧化石墨烯, 纳米氧化铜, 微生物群落, 功能预测, 防御机制