【作者】 刘杰；

【导师】 陈振楼； 许世远；

【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，受化肥施用、化石燃烧和污水排放等高强度的人类活动的影响，长江口水体出现严重的活性无机氮污染，产生了诸如水质恶化、富营养化、生态退化、饮水安全等一系列现实和潜在的生态环境问题。河口潮滩是海陆交互作用的重要环境界面，其水动力作用强烈、泥沙输移和冲淤变化复杂、生物多样丰富，具有独特的环境功能和生态价值，尤其在清除河口陆源氮污染方面起着十分重要的作用。然而，滨岸大规模开发使长江口潮滩生态系统遭到严重的干扰和破坏，如何科学利用长江口湿地资源，保护湿地生态环境，有效开展富营养化治理，迫切需要对潮滩湿地生源要素地球化学循环过程进行系统的科学研究。开展长江口滨岸潮滩氮元素的生物地球化学循环研究，具有全球性环境学意义，亦符合我国滨岸地区可持续发展的社会经济研究需求。 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”和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”等课题为支撑，开展了多年实验室和现场模拟研究，着重分析了长江口潮滩无机氮污染负荷的空间分布模式及季节变化特征；模拟和观测了潮滩沉积物-水界面无机氮通量交换过程；揭示了无机氮在沉积物-水界面交换的时空变化规律；探讨了无机氮污染负荷、潮滩底栖生物及水体盐度变化等因子对潮滩无机氮界面交换过程的影响及其控制机制，取得了以下主要成果： （1） 长江口潮滩水体无机氮多年平均含量高达130.47μmol·L^-1，其中硝氮、氨氮和亚硝氮分别约占无机氮含量的88％、11％和1％。部分污染地段三态氮含量高达485.97μmol·L^-1（硝氮）、65.43μmol·L^-1（氨氮）和34.81μmol·L^-1（亚硝氮），严重的无机氮污染将给河口生态系统健康及区域饮水安全造成严重的潜在威胁。潮滩水体氨氮和亚硝氮含量表现出上游高于下游，南岸高于北岸的分布特征，而硝氮和总无机氮则是下游高于上游。潮滩水体各形态氮在沿岸排污点附近显出超高累积特征，在远离两岸的江岛滩地含量较低。无机氮负荷量的季节分布模式复杂多变，总体上氨氮含量冬春季大于夏秋季，亚硝氮在高温季节含量较高。 （2） 实验室通量模拟实验结果表明，长江口潮滩无机氮界面交换通量变化范更多还原

【Abstract】 Derived from intensive human activities such as fertilizer usage, fossil fuels combustion and sewage discharge in recent decades, aquatic environments in coastal areas all over the whorld have encountered serious dissolved inorganic nitrogen pollution, resulting in many existent and potential ecological and environmental issues such as water quality depravation, coastal eutrophication, ecological degradation, drinking water risk and so on. The Yangtze river is third biggest river in the world with a total catchment area about 18 million km~2 and a population more than 4 ×10~8 . In the past decades, increasing riverine nitrogen inputs due to gigantic loss of farmland nitrogen fertilizer and domestic sewage discharge have seriously influenced the Yangtze estuarine water qualities and the ecological security of the delta area. In the outer estuarine area, the frequency and the area of red tide have increased in past years. This issue has affected the economic and sustainable development of the Yangtze delta.As typical ecotone between terrestrial and oceanic ecosystems, the estuarine tidal flat is widely identified as one of the most valuable and vulnerable habitats with many particular characteristics such as powerful tidal and riverine hydrodynamic processes, frequent sediment transportation and matter exchange, acute physical and chemical gradients, and various organism species. The estuarine tidal flats have a series of environmental functions and ecological values, particularly it is recognized as a natural barrier in purifying terrigenous nitrogen input. However, extensive exploitations and developments in the Yangtze estuarine coastal zone in recent years have badly disturbed and destroyed tidal flat environments and ecosystems. In order to make proper use of estuarine tidal flat resources, protect estuarine tidal flat environments and ecological balance, prevent and cure estuarine eutrophication effectively, it is urgent to carry out systemic researches on the nutrient biogeochemical cycles and processes in the Yangtze estuarine coastal tidal flats. Studies on DIN Exchanges at the sediment-water interface of the Yangtze estuarine tidal flats is of global environment significance and in accordance with economic research demands for sustainable development in eastern coastal area of China.This dissertation was supported by the National Nature Science Key Foundation of China (No.40131020), National Nature Science Foundation of China (No. 40173030), the Science & Technology Department of Shanghai Program (Grant No.05DZ120007; Grant No.05JC14059), Shanghai Environmental Bureau Program; Shanghai Basic Science Research Key Program (No.02DJ14029), and Foundation for更多还原