湿地系统规模性厌氧氨氧化反应的发生、分布与热区
文献类型：学位论文
| 作者 | 周磊榴 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 祝贵兵 |
| 关键词 | 氧氨氧化 活性 湿地生态系统 热区 表层沉积物 /土壤 深层土壤 anaerobic ammonium oxidation (anammox) activity wetland ecosystem hotspot surface sediment/soil deep soil |
| 其他题名 | The Large-scale Occurrence, Distribution and Hotspots of Anammox in Wetland Ecosystems |
| 学位专业 | 环境工程 |
| 中文摘要 | 作为新型氮循环过程，厌氧氨氧化已经成为氮循环领域的国际研究亮点。厌氧氨氧化在自然生态系统中的研究主要集中在海洋生态系统，目前已探明海洋中存在规模性并具全球效应的厌氧氨氧化反应，在全球海洋生态系统的氮损失中贡献率高达 50 %。但是在陆地生态系统，特别是淡水生态系统，厌氧氨氧化在氮循环中的作用尚不明确。 湿地，特别是湿地的两相界面如水 -土壤界面、水-沉积物界面以及地表-地下水界面，由于存在交替的好氧、厌氧环境，很有可能发生规模性的厌氧氨氧化反应，因为厌氧氨氧化反应需要氧化态氮（ NOx-）和还原态氮（NH4+）的共存。故本研究以中国典型淡水湿地为研究对象，利用包括定量 PCR、克隆文库构建在内的分子生物学技术与 15N同位素示踪技术相结合，在水平与垂直两个尺度上研究湿地系统规模性厌氧氨氧化反应的发生、分布与热区，以探讨湿地生态系统中厌氧氨氧化反应对氮损失的影响。 基于中国 7种不同湿地类型（湖泊、河流、泥炭、沼泽、水库、稻田和人工湿地）35个湿地的 208个表层沉积物/土壤样品，本研究对水平尺度不同界面（水-土壤界面、水-沉积物界面）的厌氧氨氧化进行研究，发现厌氧氨氧化在湿地生态系统广泛存在并具有规模性效应，而旱地表层土壤中并未检测到规模性厌氧氨氧化的发生。 厌氧氨氧化活性在不同湿地类型中具有很强的异质性，并具有各自的生物地理学特征。其中湖泊岸边带作为水 -土壤界面具有很高的厌氧氨氧化反应活性(348.1 – 719.6 μmol N m-2 h-1，四分位范围，n = 20），并且在氮损失中贡献了32.7 – 52.0 %（四分位范围，n = 20），显著高于其他类型湿地，是厌氧氨氧化反应的热区。这是由于湖泊垂向的水位波动加强了各种氮化合物在水和岸边带之间的交换，这个结果在嘉兴石臼漾湿地和小型人工湿地得到进一步验证。全国湿地表层沉积物/土壤中厌氧氨氧化活性在 1.0 – 1303.5 μmol N m-2 h-1之间，对氮损失的贡献在 0.9 – 82.2 %之间。结合我国各类型湿地面积估算湿地生态系统中厌氧氨氧化反应对氮损失的贡献为 1.51 Tg N yr-1，相当于总氮损失的 15.0 %，说明厌氧氨氧化在湿地生态系统中对氮损失有很大贡献。 另外，本研究在垂向尺度上对北运河岸边带深层土壤剖面中厌氧氨氧化的发生、分布与热区进行了研究，发现在潜流区（8 – 16 m，地表水与地下水相互作用的活性区域）厌氧氨氧化细菌的丰度（9.0 × 105 – 1.3 × 106 copies g-1 dry weight soil）和活性（35.2 – 111.0 μmol N m-2 h-1）都出现高峰，并且存在最高值，厌氧氨氧化对氮损失的贡献率高达 41.8 – 67.6 %。通过厌氧氨氧化反应造成的氮损失估计为 71.5 g N m-2 yr-1，占总氮损失大约 59.1 %。结果说明北运河岸边带深层土壤中的地表水-地下水界面是厌氧氨氧化反应的热区。对其他深层土壤中厌氧氨氧化细菌丰度垂向分布的研究表明，地表水 -地下水交界面存在着较高的厌氧氨氧化细菌丰度。 以上结果说明，陆地系统两相界面往往存在着规模性的厌氧氨氧化反应，如水平尺度的水-土壤界面、水-沉积物界面，垂直尺度的地表水-地下水界面。 研究结果将促进氮循环过程理论体系的修正和完善，为 N2O释放通量的重新计算提供理论基础，为水体中地表水和地下水氮的去除提供借鉴。 |
| 英文摘要 | As a newly found nitrogen cycle process, anaerobic ammonium oxidation (anammox) has become the highlight of the international research on nitrogen cycle.The present researches on anammox in natural environments mainly center on the marine ecosystem. Large-scale anammox with global effect was found in marine, and it was estimated that anammox contributed up to 50 % of the total N loss in marine. However, the role of anammox on nitrogen cycle in terrestrial ecosystem, especially the freshwater ecosystem is not well known. According to the features of the anammox substrates that there need be the coexistence of oxidized (NOx-) and reduced (NH4+) nitrogen, large-scale anammox may occur in wetlands, especially at the water-soil interfaces, the water-sediment interfaces and the surface water-groundwater interfaces of wetlands because of the alternate aerobic and anaerobic environments. So this paper took the typical Chinese wetlands as research objects, studied the large-scale occurrence, distribution and hotspot of anammox on the horizontal and vertical scale in wetlands to investigate the contribution of anammox to N loss in wetland ecosystem, using molecular biology techniques such as quantitative PCR (qPCR) and the clone library, combined with the 15N isotope labeling technique. Based on the 208 surface sediment/soil samples from 35 wetlands of 7 wetland types (lake, river, peat land, swamp, reservoir, paddy and constructed wetland) in China, we studied the anammox at different interfaces (water-soil interfaces and the water-sediment interfaces) on the horizontal scale. We found that anammox was widespread in wetlands with large-scale effect. However, there were no large-scale anammox observed in surface upland soils. Anammox activities in different wetland types were distinct greatly with each other and had their own biogeographical features. Lake littoral zones, as the water-soil interfaces, had high anammox activities (348.1 – 719.6 μmol N m-2 h-1,IQR, n = 20) and contributions to N loss (32.7 – 52.0 %, IQR, n = 20), which were significantly higher than other wetland types. So lake littoral zones were the hotspots of anammox. The reason was that the water level fluctuation of a lake was vertical and thus enhanced the exchange of various nitrogen compounds between water and littoral zone. This result was further proved in the Shijiuyang wetland, Jiaxing and a bench-scale constructed wetland. The anammox activities in various surface wetland sediments had a wide range from 1.0 to 1303.5 μmol N m-2 h-1, and the contribution to N loss was from 0.9 to 82.2 %. Combined with the area of each wetland type in China, the N loss caused by anammox in Chinese wetland ecosystem was estimated to 1.51 Tg N yr-1, which was 15.0 % of the total N loss. So anammox had a significant contribution to the N loss in wetland ecosystem. In addition, this paper studied the occurrence, distribution and hotspot of anammox in the deep soil profile of the North Canal riparian zone on the vertical scale, and found that peak zones of anammox bacterial abundance (9.0 × 105 – 1.3 × 106 copies g-1 dry weight soil) and activity (9.0 × 105 – 1.3 × 106 copies g-1 dry weight soil) and the highest values all appeared in the hyporheic zone (8 – 16 m, the active ecotone between the surface water and groundwater). The contribution of anammox to N loss in this zone was up to 41.8 – 67.6 %, and about 71.5 g m-2 yr-1 nitrogen was lost through anammox which was 59.1 % of the total N loss. So the surface water-groundwater interface of North Canal riparian zone soil profile was the anammox hotspot. The study on anammox in other deep soil profiles showed that anammox bacterial abundances were high at the surface water-groundwater interfaces. The above results indicated that large-scale anammox often existed at the interface of two phases in terrestrial ecosystem, for example, the water-soil interfaces and the water-sediment interfaces on the horizontal scale, and the surface water-groundwater interfaces on the vertical scale. The results will revise and improve the theoretical system of nitrogen cycle,provide the theoretical basis for the recalculation of N2O flux, and set examples for the removal of nitrogen from surface water and groundwater. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15720]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 周磊榴. 湿地系统规模性厌氧氨氧化反应的发生、分布与热区[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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