RCEES OpenIR  > 环境水质学国家重点实验室
湿地岸边带 有机氮矿化和氨氧化过程机制
Alternative TitleProcess and Mechanism of Organic Nitrogen Mineralization and Ammonia Oxidation in the Riparian Zone of Wetland
刘炜玥
Subtype硕士
Thesis Advisor王为东
2019-05
Degree Grantor中国科学院生态环境研究中心
Place of Conferral北京
Degree Name工程硕士
Degree Discipline环境工程
Keyword湿地岸边带 ,矿化 过程 ,氨氧化过程 氮反应速率, 微生物丰度 wetland Riparian Zone, Mineralization, Ammonium Oxidation, Nitrogen Reaction Rate, Microbial Abundance
Abstract

      我国受污染 地表水中 总氮 仍处于 较高水平 去除总氮 特别是其中 占 比 较大的有机 形态 氮 是提高 受纳水体 水质 的重要途径。 目前, 国内外 针 对 有机氮 矿化及其后续氨氧化过程相关功能微生物作用机 制 的研究 尚不 充分。 而 湿地岸边带 作为水体 与 陆地 之间 的过渡 地带 具有 独特的 生态 环境特性和生态 服务 功能,是氮循环反应的关键 区域。 研究 湿地岸边带 有机氮 矿化和氨氧化过程机制, 解析 氮转化效率和微生物群落结构的 关键 影响 因素 ,对丰富氮循环理论、 优化 岸边带 结构和功能、 削减 总氮污染具有重要意义 。本论文在 人工湿地 、湖泊 湿地 和全球多类型湿地 等 三个尺度上开展研究 ,主要获得以下结果:
      在人工构筑 的 植物床 -沟壕湿地中 小沟边缘 沉积物 是拥有 最 高 有机氮矿化潜势 3.41 ± 0.23 mg·(kg·d)-1)和独特微生物群落结构 的区域 。 微生物 Bacillus(芽孢杆菌属) 、 Pseudomonas(假单胞菌属 和 好氧反硝化细菌如 Rhodobacter(红细菌属)、 Flavobacterium(黄杆菌属 )和 Dechloromonas(脱氮单胞菌属)等对有机氮矿化速率有较大贡献。 氨化 过程 是 植物床 -沟壕湿地 中 有机氮矿化的主要过程 ,其 速率与总有机氮、 有机质 含量 、 沉积物粒径 比表面积呈正相关 。 湿地的水力 状况 、水流速率、 植 物作用 决定了 有机氮矿化过程 的 空间差异。 湿地 演替时间 显著影响 微生物群落结构 5年演替 期 的 贯泾港湿地 其 沉积物具 较高氨氮含量2.30 ± 0.18 mg·kg-1 、 有机氮矿化速率 6.03 ± 0.79 mg·(kg·d)-1 其 特有 菌以Acidobacteria 酸杆菌 )、 Planctomycetes 浮霉状菌 )、 Alphaproteobacteria α-变形菌)等为主 而 10年 演替期 的 石臼漾湿地演化出 更高 丰度 的硝化细菌和反硝化细菌 。
      在富营养化 湖泊湿地 中 有机氮矿化 潜势 较植物床 -沟壕 湿地 中 更高,且 氨化过程贡献 率 约 占 90%。 湖泊沉积物中 氨氧化速率很低, 造成 湖底 氨氮 累积 ,成为 湖泊潜在 的 内源污染 。 与 开阔湖区相比, 湖滨带 区 域 微生物丰度较高 。 相关微生物 丰度 呈现不同 时空 分布格局 ,其 机制不 同 。 氨氧化古菌( AOA 、 厌氧氨氧化细菌 丰度呈现空间异质性 而 受温度影响 不 大 。 氨氧化细菌 丰度 变化受温度影响 较大 ,而群落结构 受 氨氮 影响较大 。反硝化细菌 、 硝酸盐异化还原成 铵 细菌DNRA 是化能异养菌, 其 丰度 对各 环境因子较敏感。 河口岸边带中 Microcycstis (微囊藻 属 )和 Anaeromyxobacter(厌氧粘细菌 、 Pseudomonas 假单孢菌属等异养细菌的丰度较高。 宏基因组学分析发现, 湖泊湿地沉积物中 与氨基酸代谢相关的蛋白数量最多, 氮代谢网络中各个过程在 开阔湖区、湖滨带 差异不明显 。
      在全球多类型湿地尺度上,不同类型 湿地中 AOA的丰度、活性和群落组成具有很强的异质性。 其中 pH是对 AOA丰度 影响最大的环境因素, 呈 负相关 。AOA在 超过三分之二的 湿地沉积物中 贡献了 超过 50%的 氨氧化速率。 其中Candidatus Nitrosocosmicus franklandus属的相对丰度与古菌氨氧化速率呈显著正相关, 并且碳 利用效率较高,因而是古菌氨氧化过程 的主导功能微生物 。
      根据以上湿地岸边带有机氮矿化和氨氧化过程机制的研究结果,提出调控湿地 水力 条件 创造 厌氧 /好氧 交 叠 环境、恢复天然水体岸边带植被、强化优势功能微生物的丰度和活性等措施对水体总氮去除有积极作用。

Other Abstract

       Total nitrogen level in the polluted surface waters in China is still at a high level. Removal of total nitrogen especially the organic forms is an important pathway to improve the water quality of receiving waters. Presently the mechanism researches on organic nitrogen mineralization and the subsequent ammonia oxidation process as well as the related functional microorganisms is still insufficient. Wetland riparian zones as interfaces between waters and land exhibit unique eco-environmental features and ecological service functions, thus being “hotspots” of nitrogen (N) cycling reactions. It is of great significance to study the process mechanism of nitrogen mineralization and ammonia oxidation in the riparian zones, and to explore the key factors influencing the nitrogen removal performance and microbial community structure. This will help extend the theory of nitrogen cyclings, optimize the structure and function of riparian zones, and mitigate total nitrogen pollution. In this thesis, studies had been developed on constructed wetland, lacustrine wetland and many kinds of global wetlands. The main results were summarized as follows.
       In the constructed plant-bed/ditch wetlands, small ditch fringe harbored the highest organic nitrogen mineralization rate (3.41 ± 0.23 mg·(kg·d)-1) and exclusive microbial community structure. Microbes Bacillus, Pseudomonas and aerobic denitrifying bacteria such as Rhodobacter, Flavobacterium and Dechloromonas contribute much to the organic nitrogen mineralization rate. Ammonifying process was the main process of organic nitrogen mineralization in the constructed plant-bed/ditch wetlands. The ammonification rate was positively correlated with total organic nitrogen, organic matter and specific surface area of sediment particles. Hydraulic conditions, water flow rate and hydrophyte interactions in wetland determined the spatial heterogenity of mineralization process. The operational duration of wetland had significant effects on the microbial community structure in the sediments. Guanjinggang wetland with a shorter operational duration (5 years) contained higher sedimentary ammonia nitrogen content (2.30 ± 0.18 mg·kg-1) and organic nitrogen mineralization rate (6.03 ± 0.79 mg·(kg·d)-1). Microbes Acidobacteria, Planctomycetes and Alphaproteobacteria were the dominated bacteria. Shijiuyang wetland with a 10-year operational duration evolved more abundance of nitrifying and denitrifying bacteria.
       In the eutrophic lake wetland, the potential organic nitrogen mineralization rate was higher than that in the constructed plant-bed/ditch wetlands, and ammonifying process contributed about 90% to the mineralization rate. The ammonia oxidation rate was low in the lake sediments, which resulted in ammonia nitrogen accumulation in the lake bottom and posed potential internal pollution sources. The microbial abundance in the lake riparian zone was higher than that in the lake open water area. The abundance of N-cycle-related microorganisms showed spatiotemporal distribution variations and mechanisms differed. The abundance of ammonia-oxidizing archaea (AOA) and anammox bacteria showed spatial heterogeneity, but varied little temporally (as per temperature). The abundance and community structure of ammonia-oxidizing bacteria were affected by temperature and ammonia nitrogen content respectively. The abundance of chemoorganotrophic denitrifying bacteria and DNRA bacteria was sensitive to various environmental factors. Heterotrophic bacteria such as Microcycstis, Aneromyxobacter and Pseudomonas were abundant in the lake riparian zone. Macrogenomic analysis revealed that the largest number of proteins was associated with amino acid metabolism. There was no significant difference in the processes of nitrogen metabolism network between the lake riparian zone and open water area.
        On the global scale of various wetlands, the abundance, activity and community composition of AOA showed significant heterogeneity. pH was the most important environmental factor netagively affecting AOA abundance. AOA contributed more than 50% of ammonia oxidation rate in more than two-thirds of the studied wetlands. Among AOA, the relative abundance of Candidatus Nitrosocosmicus franklandus was positively correlated with the archaeal ammonia oxidation rate, and its carbon utilization efficiency was higher than others, so it was the dominant functional microorganism in the ammonia oxidation process of archaea.
        Based on the above results on the microbial mechanism of organic nitrogen mineralization and ammonia oxidation process in the riparian zones, we proposed that measures including (1) regulating hydraulic conditions to create anaerobic / aerobic alternating wetland environment, (2) restoring vegetation in the riparian zones, and (3) strengthening the abundance and activity of dominant functional microorganisms would play a positive role in improving the total nitrogen removal in water body.

Pages97
Language中文
Document Type学位论文
Identifierhttp://ir.rcees.ac.cn/handle/311016/42254
Collection环境水质学国家重点实验室
Recommended Citation
GB/T 7714
刘炜玥. 湿地岸边带 有机氮矿化和氨氧化过程机制[D]. 北京. 中国科学院生态环境研究中心,2019.
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