纳米氧化锌粒径对人工湿地性能及微生物群落的影响

纳米颗粒(nanoparticles,NPs)具有较小的粒径(1～100 nm),其生物毒性与粒径的大小紧密相关.在进水COD约200. 0 mg·L~(-1),NH_4~+-N约12. 5 mg·L~(-1)和溶解性总磷约4. 0 mg·L~(-1)的条件下连续运行28 d,研究了3种不同粒径的纳米氧化锌(ZnO NPs)对水平潜流人工湿地微生物群落结构和多样性的影响,同时结合湿地脱氮性能的变化,探讨了湿地中微生物群落结构和多样性与其处理性能的相互关系.结果表明,3种粒径(15、50和90 nm)的ZnO NPs(10 mg·L~(-1))对COD的去除无明显差异,而对脱氮则表现出明显的粒径效应.高通量测序发现,人工湿地系统中硝化菌属的丰度明显低于反硝化菌属,硝化过程是制约湿地脱氮性能的关键因素.暴露于不同粒径的ZnO NPs后,微生物群落结构发生不同程度的变化,与较大粒径(50 nm和90 nm)的ZnO NPs相比,15 nm的ZnO NPs对硝化菌属的抑制更为显著.

Size-dependent Effects of Zinc Oxide Nanoparticles on Performance and Microbial Community Structure of a Constructed Wetland

Nanoparticles (NPs) have increasingly been applied in consumer and industrial products because of their magnetic, optical, electronic, sensitive, antibacterial, disinfection, and UV shielding properties. The wide production and application of NPs has inevitably resulted in their release into the ecosystem through various channels and accumulation in organisms. NPs have a small particle size (1-100 nm), which is closely correlated with biotoxicity. To investigate the size-dependent effects of zinc oxide nanoparticles (ZnO NPs) on microbial community structure and diversity, as well as the nitrogen removal performance of a biological treatment system, laboratory scale horizontal subsurface flow constructed wetlands were operated for 28 days under the conditions of COD 200.0 mg·L^-1, NH₄⁺-N 12.5 mg·L^-1, and total dissolved phosphorus 4.0 mg·L^-1. The relationship between microbial community structure and its performance were discussed. The results indicated that three sized ZnO NPs (15, 50, and 90 nm) had no significant effect on COD removal at the concentration of 10 mg·L^-1 but showed obvious particle size effects on nitrogen removal. High throughput sequencing indicated that the abundance of nitrifying bacteria in constructed wetland system was significantly lower than that of denitrifying bacteria, suggesting that the nitrification process was the key factor restricting the denitrification performance of wetlands. After exposure to ZnO NPs, the structure of microbial communities in constructed wetlands changed, and 15 nm ZnO NPs had a stronger inhibitory effect on nitrifying bacteria than those of 50 nm and 90 nm ZnO NPs.