Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, PR China.
Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, PR China.
Sci Total Environ. 2022 Nov 25;849:157876. doi: 10.1016/j.scitotenv.2022.157876. Epub 2022 Aug 6.
The extensive application of nitrogen fertilizer in intensive irrigation areas poses a potential threat to groundwater. Given that the vadose zone acts as a buffer zone for the underground entry of surface pollutants, an in-depth understanding of its microbial community structure and function was crucial for controlling groundwater nitrogen pollution. In this study, soil samples from paddy vadose under groundwater irrigation with different depths (G1: 6.8 m, G2: 13.7 m, G3: 15.6 m, and G4: 17.8 m) were collected to unravel the differences in microbial community structure and function at different vadose depths (0-250 cm), as well as their relationship with soil properties. Results showed some differences among soil physicochemical factors under groundwater irrigation with different depths and that some electron acceptors were more abundant than others under deep groundwater irrigation (G2-G4). Remarkable differences in microbial communities under shallow- and deep-groundwater irrigation were found. The high abundances of anammox bacteria Candidatus_Brocadia in G2 and G3 indicated that deep groundwater irrigation was beneficial to its enrichment. Iron-reducing bacteria Anaeromyxobacter and sulfate-reducing bacteria Desulfovibrio were widely distributed in vadose zone and possessed the potential for anammox coupled with Fe(III)/sulfate reduction. Norank_f_Gemmatimonadaceae had nitrate- and vanadium-reducing abilities and could participate in anammox in vadose zone. Dissimilatory nitrate reduction to ammonia (DNRA) bacteria Geobacter facilitated Fe(II)-driven DNRA and thus provided electron donors and acceptors to anammox bacteria. Soil nutrients and electron donors/acceptors played important roles in shaping microbial community structure at phylum and genus levels. Microorganisms in vadose zone under groundwater irrigation showed good material/energy metabolism levels. Deep groundwater irrigation was conducive to the occurrence of anammox coupled with multi-electron acceptors. Our findings highlight the importance of understanding the structure and function of microbial communities in paddy vadose under groundwater irrigation and reveal the potential role of indigenous microorganisms in in-situ nitrogen removal.
在集约化灌溉区广泛应用氮肥对地下水构成潜在威胁。鉴于包气带是地表污染物进入地下的缓冲区，深入了解其微生物群落结构和功能对于控制地下水氮污染至关重要。在这项研究中，采集了不同深度地下水灌溉稻田包气带（G1：6.8 m，G2：13.7 m，G3：15.6 m 和 G4：17.8 m）下的土壤样本，以揭示不同包气带深度（0-250 cm）下微生物群落结构和功能的差异，以及它们与土壤性质的关系。结果表明，不同深度地下水灌溉下的土壤理化因子存在一些差异，深层地下水灌溉下一些电子受体比其他电子受体更丰富。浅地下水和深地下水灌溉下的微生物群落存在显著差异。G2 和 G3 中厌氧氨氧化菌 Candidatus_Brocadia 的高丰度表明，深地下水灌溉有利于其富集。铁还原菌 Anaeromyxobacter 和硫酸盐还原菌 Desulfovibrio 在包气带中广泛分布，具有与 Fe(III)/硫酸盐还原偶联的厌氧氨氧化潜力。Norank_f_Gemmatimonadaceae 具有硝酸盐和钒还原能力，可参与包气带中的厌氧氨氧化。异化硝酸盐还原为氨（DNRA）细菌 Geobacter 促进了 Fe(II)驱动的 DNRA，从而为厌氧氨氧化细菌提供了电子供体和受体。土壤养分和电子供体/受体在门和属水平上对微生物群落结构的形成起着重要作用。包气带中的微生物表现出良好的物质/能量代谢水平。深地下水灌溉有利于多电子受体偶联的厌氧氨氧化的发生。我们的研究结果强调了了解地下水灌溉稻田包气带微生物群落结构和功能的重要性，并揭示了土著微生物在原位脱氮中的潜在作用。
