人工湿地各组分氮素削减定量及功能基因分析

Quantification of nitrogen reduction of each component in constructed wetland and functional gene analysis

为探讨人工湿地各组分氮素削减贡献度及微生物脱氮机理,本研究构建6组(3组无植物对照)不同类型人工湿地系统,3组有植物人工湿地基质分别为陶粒+煤渣、陶粒+沸石、沸石+煤渣,探究其对包头南海湖水中氮素的去除效果;采用氮稳定同位素示踪技术,量化植物、基质和微生物在人工湿地氮去除中的贡献度;并利用高通量测序技术分析人工湿地系统中微生物的群落结构及氮代谢功能基因。结果表明:陶粒+煤渣有植物组人工湿地氮去除效果最佳,对TN、NH_(4)^(+)-N、NO_(3)^(-)-N、NO_(2)^(-)-N的去除率分别为(41.18±2.61)%、(50.44±2.63)%、(40.93±2.32)%、(74.34±1.97)%。^(15)N示踪发现,植物、基质和微生物对人工湿地系统NO_(3)^(-)-N去除的贡献率分别为27.74%、48.43%和23.83%。高通量测序和PICRUSt2功能预测分析结果表明,植物对微生物群落组成和代谢途径有显著影响。在植物根部样本中,优势菌门为Proteobacteria,其大部分菌属均参与了氮代谢,在生物脱氮过程中发挥重要的作用。有植物人工湿地系统基质中微生物的nir S基因、植物根系的nir K基因丰度明显增加,植物有效促进了人工湿地系统中微生物的反硝化作用。

Six groups(three groups without plants)of constructed wetland systems with substrates of ceramic pellets+cinder,ceramic pellets+zeolite,and zeolite+cinder were constructed to investigate the effect of nitrogen removal in Baotou Nanhai Lake and explore the contribution of nitrogen reduction of each component in a constructed wetland and the mechanism of microbial nitrogen removal.Nitrogen stable isotope tracing technology was used to quantify the contribution of plants,substrates,and microorganisms to nitrogen removal in a constructed wetland.High-throughput sequencing technology was used to investigate the microbial community structure and nitrogen metabolism functional genes in the system.The results showed that the constructed wetland with plants comprising ceramic+cinder was the most effective in nitrogen removal,with removal rates of(41.18±2.61)%,(50.44±2.63)%,(40.93±2.32)%,and(74.34±1.97)% for TN,NH_(4)^(+)-N,NO_(3)^(-)-N,and NO_(2)^(-)-N,respectively.15N tracing revealed that the contribution rates of plants,substrates,and microorganisms to the NO_(3)^(-)-N removal in the constructed wetland system were 27.74%,48.43%,and 23.83%,respectively.High-throughput sequencing and PICRUSt2 functional prediction results revealed that plants significantly impacted microbial composition and metabolic pathways.The dominant phylum was Proteobacteria,most of whose genera are involved in the nitrogen cycle and are crucial in biological denitrification.The abundance of nirS on the substrate and nirK in the plant roots of a planted constructed wetland system increased significantly.Plants effectively promoted the denitrification of microorganisms in constructed wetland systems.