Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Sci Total Environ. 2018 Nov 15;642:1090-1099. doi: 10.1016/j.scitotenv.2018.06.110. Epub 2018 Jun 19.
As aquatic-terrestrial ecotones, riparian zones are hotspots not only for denitrification but also for nitrous oxide (NO) emission. Due to the potential role of nosZ II in NO mitigation, emerging studies in terrestrial ecosystems have taken this newly reported NO-reducer into account. However, our knowledge about the interactions between denitrification activities and both NO-producers and reducers (especially for nosZ II) in aquatic ecosystems remains limited. In this study, we investigated spatiotemporal distributions of in situ NO flux, potential NO production rate, and potential denitrification rate, as well as of the related genes in a riparian zone of Baiyangdian Lake. Real-time quantitative PCR (qPCR) and high-throughput sequencing targeted functional genes were used to analyze the denitrifier communities. Results showed that great differences in microbial activities and abundances were observed between sites and seasons. Waterward sediments (constantly flooded area) had the lowest NO production potential in both seasons. Not only the environmental factors (moisture content, NH content and TOM) but also the community structure of NO-producers and NO-reducers (nirK/nirS and nosZ II/nosZ I ratios) could affect the potential NO production rate. The abundance of the four functional genes in the winter was higher than in the summer, and the values all peaked at the occasionally flooded area in the winter. The dissimilarity in community composition was mainly driven by moisture content. Altogether, we propose that the NO production potential was largely regulated by the community structure of NO-producers and NO-reducers in riparian zones. Increasing the constantly flooded area and reducing the occasionally flooded area of lake ecosystems may help reduce the level of denitrifier-produced NO.
作为水陆交错带，河岸带不仅是反硝化作用的热点区域，也是氧化亚氮（NO）排放的热点区域。由于 nosZ II 在减少 NO 方面的潜在作用，陆地生态系统中的新兴研究已经考虑到这种新报道的 NO 还原剂。然而，我们对水生生态系统中反硝化作用与 NO 产生者和还原剂（特别是 nosZ II）之间的相互作用的了解仍然有限。在这项研究中，我们调查了白洋淀河岸带的原位 NO 通量、潜在 NO 产生速率和潜在反硝化速率以及相关基因的时空分布。实时定量 PCR（qPCR）和高通量测序靶向功能基因用于分析反硝化菌群落。结果表明，不同地点和季节的微生物活性和丰度存在很大差异。向水沉积物（持续淹没区）在两个季节的潜在 NO 产生潜力最低。不仅环境因素（水分含量、NH 含量和 TOM），还有 NO 产生者和 NO 还原剂（nirK/nirS 和 nosZ II/nosZ I 比值）的群落结构都可能影响潜在的 NO 产生速率。四个功能基因在冬季的丰度高于夏季，冬季偶尔淹没区的丰度最高。群落组成的差异主要受水分含量的驱动。总的来说，我们提出河岸带中 NO 产生者和 NO 还原剂的群落结构在很大程度上调节了潜在的 NO 产生潜力。增加湖泊生态系统的持续淹没区和减少偶尔淹没区可能有助于降低反硝化产生的 NO 水平。
