You Aiju, Hua Lei, Hu Jingwen, Tian Junsong, Ding Tao, Cheng Na, Hu Lifang
Zhejiang Institute of Hydraulics & Estuary, Zhejiang Institute of Marine Planning & Design, Hangzhou, 310020, China.
College of Quality and Safety Engineering, Institution of Industrial Carbon Metrology, China Jiliang University, Hangzhou, 310018, China.
J Environ Manage. 2023 Oct 15;344:118733. doi: 10.1016/j.jenvman.2023.118733. Epub 2023 Aug 8.
Protection and rectification patters of urban wetlands have been considered in strategies to balance services to society and negative consequences of excess reactive nitrogen (Nr) loading. However, the knowledge about strategies of semi-constructed wetlands on nitrogen (N) cycling pathways and removal Nr from the overlying water is limited. This study aimed to reveal considerable differences among rectification patterns of the typical semi-constructed wetland (Xixi wetland), comprising rational exploitation area (REA), rehabilitation and reconstruction area (RRA), and conservation area (CA) by analyzing the N distribution and N protentional pathways among them. Results pointed out that both NH and NO concentration were prominently higher in REA, as opposed to CA and RRA. Sediments in RRA had relatively higher NH content, indicating the efficiency of dissimilatory nitrate reduction (DNRA) in RRA. Moreover, there was a significant shift in the microbial community structure across different sites and sediments. Metagenomic analysis distinguished the N cycling pathways, with nitrification (M00804), denitrification (M00529), and DNRA (M00530) being the crucial pathways in the semi-constructed wetland. The relative abundance of N metabolic pathways (ko00910) varied among different types of sediments, being more abundant in shore and rhizosphere areas and less abundant in bottom sediments. Methylobacter and Nitrospira were the predominant nitrifiers in shore sediments, while Methylocystis was enriched in the bottom sediments and rhizosphere soils. Furthermore, Anaeromyxobacter, Anaerolinea, Dechloromonas, Nocardioides, and Methylocystis were identified as the primary denitrifiers with N reductase genes (nirK, nirS, or nosZ). Among these, Anaeromyxobacter, Dechloromonas, and Methylocystis were the primary contributors containing the nosZ gene in semi-constructed wetlands, driving the conversion of NO to N. This study provides important insights into rectification-dependent Nr removal from the overlying water in terms of N distribution and N metabolic functional microbial communities in the semi-constructed wetlands.
城市湿地的保护与整治模式已被纳入平衡社会服务与过量活性氮（Nr）负荷负面影响的战略中。然而，关于半人工湿地氮（N）循环途径及从覆水去除Nr策略的知识有限。本研究旨在通过分析典型半人工湿地（西溪湿地）的合理开发区（REA）、修复重建区（RRA）和保护区（CA）之间的氮分布和潜在氮途径，揭示它们在整治模式上的显著差异。结果指出，与CA和RRA相比，REA中的NH和NO浓度显著更高。RRA中的沉积物NH含量相对较高，表明RRA中异化硝酸盐还原（DNRA）的效率。此外，不同地点和沉积物的微生物群落结构存在显著变化。宏基因组分析区分了氮循环途径，硝化作用（M00804）、反硝化作用（M00529）和DNRA（M00530）是半人工湿地中的关键途径。不同类型沉积物中氮代谢途径（ko00910）的相对丰度各不相同，在岸边和根际区域更为丰富，而在底部沉积物中则较少。甲基杆菌属和硝化螺菌属是岸边沉积物中的主要硝化菌，而甲基孢囊菌属在底部沉积物和根际土壤中富集。此外，厌氧粘细菌属、厌氧绳菌属、脱氯单胞菌属、诺卡氏菌属和甲基孢囊菌属被鉴定为具有氮还原酶基因（nirK、nirS或nosZ）的主要反硝化菌。其中，厌氧粘细菌属、脱氯单胞菌属和甲基孢囊菌属是半人工湿地中含有nosZ基因的主要贡献者，推动了NO向N的转化。本研究在半人工湿地的氮分布和氮代谢功能微生物群落方面，为依赖整治的覆水Nr去除提供了重要见解。
