| 摘要: |
| 氮元素在自然界中的迁移转化是维持生态系统平衡的关键过程。在自然水体中，河流沉积物的氮功能菌在氮转化过程中起着至关重要的作用。为探究河流氮分布及沉积物微生物驱动过程，本文针对岷江上游三个海拔河段的水体和沉积物进行氮分布研究，通过高通量测序等技术分析沉积物微生物群落组成及功能预测。结果表明：在岷江上游高海拔河段（>3000m），沉积物铵盐较高，沉积物硝酸盐较低，水体亚硝酸盐在2000~3000m海拔河段显著高于其他海拔河段，同时氮组分分布受到pH、溶解氧、流速等环境因子影响。岷江上游沉积物细菌群落主要受沉积物氮组分和可溶性有机碳（DOC）的影响；古菌群落主要受海拔、沉积物氮组分和土壤有机碳（SOC）的影响。岷江上游沉积物潜在氮转化微生物群落相似性在地理空间上呈显著衰减模式，且高海拔河段的潜在氮转化古菌群落具有显著差异性。其中，潜在硝化古菌是岷江上游的优势菌群，潜在硝化古菌与潜在异化型硝酸盐还原古菌且在高海拔河段显著高于较低海拔河段。对岷江上游不同氮转化过程而言，Nitrososphaerales目、Nitrososphaeraceae科、Nitrososphaeraceae属是参与硝化过程的关键菌群，黄杆菌属（Flavobacterium）是硝酸盐还原过程的关键菌群，梭状芽胞杆菌属（Clostridium_sensu_stricto_1）与慢生根瘤菌属（Bradyrhizobium）是固氮过程的主要菌群，黄色杆菌属（Xanthobacter）、副球菌属（Paracoccus）和假单胞菌属（Pseudomonas）是反硝化过程的主要菌群。本文揭示了岷江上游高海拔河段的氮分布主要受到潜在沉积物氮转化古菌的驱动，该结论可为岷江上游河流生态管理策略提供一定理论支撑。 |
| 关键词: 岷江上游 氮分布 氮转化 沉积物微生物 |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Nitrogen distribution and potential microbial driving processes in the upper reaches of Minjiang River |
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Yang Zao1, Li Naying1, Zhong Bo1, Wang Xiaofeng2, Li Xianxiang2, Liu Xin1, Mei Xintong1, He Yixin1
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1.：Chengdu Institute of Biology,Chinese Academy of Sciences;2.：School of Geography and Tourism,Chongqing Normal University
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| Abstract: |
| The migration and transformation of nitrogen in nature is the key process to maintain the balance of ecosystem. In natural water, nitrogen-transforming microorganisms in river sediments play a crucial role in the process of nitrogen conversion. In order to investigate the nitrogen distribution in rivers and the sediment microorganism driving processes, this paper studied nitrogen distribution in the upper reaches of the Minjiang River, and the composition and function prediction of microbial communities in sediments were analyzed. The results show that the sediment ammonium salt is higher and the sediment nitrate is lower in the upper reaches of the Minjiang River at high altitude (>3000m), and the water nitrite is significantly higher in the 2000-3000m altitude reaches than in other altitude reaches. Meanwhile, the distribution of nitrogen components is affected by environmental factors such as pH, dissolved oxygen and flow rate. The sediment bacterial communities were mainly affected by sediment nitrogen components and dissolved organic carbon (DOC), while the archaea community was mainly affected by altitude, sediment nitrogen composition and soil organic carbon (SOC). The similarity of potential nitrogen-transforming microbial communities showed a significant decline pattern in geographical space, and the potential nitrogen-transforming archaea communities in the high altitude reaches were significantly different. Among them, the potential nitrifying archaea were the dominant bacterial group in the upper reaches of the Minjiang River, and the potential nitrifying archaea and potential dissimilating nitrate reducing archaea were significantly higher in the high altitude reaches than in the low altitude reaches. For different processes, Nitrososphaerales, Nitrososphaeraceae and Nitrososphaeraceae are the dominant microorganisms in the nitrification process, and Flavobacterium is the main groups in the nitrogen reduction process. Clostridium_sensu_stricto_1 and Bradyrhizobium are the main groups in nitrogen fixation. Xanthobacter, Paracoccus and Pseudomonas are the main groups in denitrification. This paper reveals that nitrogen distribution in the upper reaches of the Minjiang River at high altitude is mainly driven by potential sediment nitrogen transforming archaea, these results can provide theoretical support for the ecological management strategy of the upper reaches of the Minjiang River. |
| Key words: the upper reaches of Minjiang River nitrogen distribution nitrogen transformation sediment microorganism |
