【作者】 王东启；

【导师】 许世远； 陈振楼；

【作者基本信息】 华东师范大学 ， 自然地理学， 2006， 博士

【摘要】 近几十年来高强度的人类活动，如化肥的施用和排污，导致河口地区氮素输入逐年上升，河口、近海水体快速富营养化是当今世界面临的一个重大环境问题。河口湿地作为容纳净化陆源污染物、削减其入海通量的天然屏障，在控制河口和近海水体营养状况以及全球氮循环过程中扮演着十分重要的角色。据估算，河口湿地通常可清除10～60％的氮负荷，反硝化反应在其中起到了非常重要的作用。 反硝化是全球氮循环中的关键环节，是将陆地、水体生态系统等氮库中生物可利用态氮转化成惰性气态氮归还到大气圈中的主要途径，在保持岩石圈、水圈、生物圈和大气圈氮素平衡中起着极为重要的作用。缺氧条件下，NO₃^-被还原为N₂和N₂O，因为N₂在大气中的丰富含量，不会因为氮素的不断输入而导致这个氮汇达到饱和，反硝化被认为是去除污水或者富氧环境中氮素的最好手段。 然而N₂O是一种最重要的温室气体，增温效应显著且在大气层滞留期长，具有非常高的增温潜势。此外N₂O的氧化导致了臭氧层的破坏；在平流层低部，N₂O分解产生的NOx经化学反应后形成HNO_X酸性降水，同时作为温室气体加剧温室效应。因此，近年来全球N₂O排放和吸收源汇通量以及其在大气层中浓度的上升受到了广泛关注。 在河口滨岸地区，海陆交互作用陆源物质在河口地区沉降、堆积，使得河口地区沉积物成为陆源氮、碳的巨大汇库，同时潮滩植被的生长和埋藏，使得潮滩湿地成为全球氮、碳库的重要组成。在淤长型潮滩地区，潮滩的演替、植被生长对沉积物中生源要素的分解、释放、埋藏等生物地球化学过程有着重要的影响。河口滨岸湿地这一复杂巨系统内生源要素的来源、分布、富集、迁移和转化等生物地球化学循环过程已成为当前河口滨岸环境地球化学等领域的热点问题之一。 本文以国家自然科学基金重点项目“长江口滨岸潮滩复杂环境条件下物质循环研究”、国家自然科学基金项目“长江口潮滩沉积物—水界面氮的季节性迁移与反硝化作用”、上海市科委和环保局项目“长江口潮滩环境质量调控预测模型研究”、上海市基础研究重点项目“长江口潮滩污染物源汇通量及其生态效应”、教育部优秀青年教师资助计划“长江口滨岸潮滩氮的界面交换通量与循环机制研究”、华东师范大学2005年优秀博士生培养基金等研究课题为依托，在广泛收集国内外相关研究文献、前人研究成果的基础上，以大量野外采样、现场监测和室内模拟、分析相结合，首次在我国河口、滨岸地区系统开展了潮滩湿地反硝化以更多还原

【Abstract】 In recent decades, high intensity human activity, such as chemical fertilizer employment and drainage, induced the increase of nitrogen year after year which was transported into estuarine area. Quickly eutrophication in estuarine coastal water body is one of the serious globe environment problems in the world. Estuarine wetland is a natural barrier in purifying terrigenous pollutions and attenuating the riverine load to the sea, it plays a key role in controlling marine eutrophication and global nitrogen cycle. It was estimated that estuarine sediment could eliminate 10-60% territorial nitrogen load, among this, denitrification is an important process.As a key process of nitrogen cycle, denitrification is an important approach to transfer nitrogen in terrestrial and aquatic ecosystem into atmosphere, and has a key role on keeping nitrogen balance among the lithosphere, hydrosphere, biosphere and atmosphere. In the anoxic condition, nitrate will become electron acceptance instead of oxygen, much of it being converted into N₂ and a small proportion into N2O, and then enter into atmosphere. Because N₂ is abundant in the earth’s atmosphere and inert, denitrification is considered as the most desirable means for nitrate removal from polluted and eutrophication water environment and this sink will never become saturation with nitrogen because of the nitrogen importing continuously.While N₂O is one of major atmospheric greenhouse gases, its greenhouse effect is prominent and has a long lifespan in the atmosphere, and thus has a large greenhouse wanning potential. At the same time it contributes to ozone destruction resulting in stratospheric ozone depletion, and at the bottom of stratosphere, it could be converted into NOx and then into HNO_x forming the acid precipitation. The converted production could also enhance the greenhouse effect. So in recent years, abundant attentions were put on the global N₂O emission and consumption flux and its concentration increasing in the atmosphere.In estuarine coastal area, terrigenous particular settle and deposit in this area by the land-sea interaction. The sediment is a huge pool of terrigenous nitrogen and carbon element. At the tidal flat, the growth and bury of plant make the tidal flat wetland as the important portion of global nitrogen and carbon pool. In the alluvial更多还原