长江口硝酸盐异化还原过程及其影响因素研究

发布时间：2018-04-24 14:17

  本文选题：反硝化 + 厌氧氨氧化　； 参考：《华东师范大学》2016年硕士论文

【摘要】：氮是影响河口近海岸水环境生态系统的关键生源要素之一。在过去的几十年间,由于人类活动加剧,排放到环境中的活性氮含量增加了120%,开展河口近海岸氮素的迁移转化过程研究成为当今国际上热点科学问题。过量的活性氮输入给河口近海岸生态系统造成了一系列生态环境问题,包括种群结构的变化、生物多样性的减少、低氧区域的形成以及蓝藻赤潮频繁爆发。因此,深入开展河口海岸环境氮循环研究,可加深对河口近海岸氮循环转化过程的理论认识,并了解氮素的归宿以及对于控制日益严峻的氮污染问题具有重要的现实意义。水环境中的硝酸盐异化还原过程主要包括反硝化、厌氧氨氧化和硝酸盐异化还原成氨(DNRA)过程,不同的过程在氮素的转化和归宿中扮演着不同的角色。反硝化与厌氧氨氧化是水体中最为重要的活性氮削减过程,将硝酸盐或者氨氮转化为氮气,永久性的脱离水体。在DNRA过程中,硝态氮的归宿不同于反硝化和厌氧氨氧化,在DNRA过程中硝酸盐转换为铵盐,以一种更具生物有效性的形式继续残留在水环境系统中。深入了解氮素在河口海岸地区的迁移转化和循环过程,对于评价河口生态系统的潜在环境影响效应、协调环境保护与可持续发展具有重要的应用价值和指导意义。本文以长江口作为典型研究区,采样泥浆实验结合同位素示踪技术研究了长江口沉积物中反硝化、厌氧氨氧化和DNRA潜在速率,探究沉积物环境因子对硝酸盐异化还原过程的影响,估算反硝化、厌氧氨氧化过程的脱氮贡献率以及DNRA过程对于脱氮过程的影响。取得主要研究成果如下：(1)长江口底层沉积物的反硝化、厌氧氨氧化以及DNRA潜在速率的范围分别是0.06-4.51 pmol N kg-1 h-1,0.01-0.52 μmol N kg-1 h-1,和 0.03-0.89 μmol N kg-111-1。长江口潮滩沉积物植被覆盖区的反硝化、厌氧氨氧化和DNRA速率分别是3.63-10.68 pmol N kg-1 h-1,0.03-0.71μmol N kg-1 h-1 和 0.87-5.57 μmol N kg-1 h-1;而非植被覆盖区域的速率为1.81-6.22 pmol N kg-1 h-1,0.03-0.23 pmol N kg-1 h-1 和 0.14-2.98 pmol N kg-1 h-1。(2)长江口沉积物中的反硝化速率变化主要受温度、硫化物、有机碳以及Fe(Ⅱ)影响；温度和硫化物对于沉积物中的厌氧氨氧化速率的分布存在明显的影响作用；影响沉积物中DNRA速率的主要环境因子是硫化物、Fe(Ⅱ)和有机碳。(3)反硝化是长江口硝酸盐削减的最主要过程,占总的硝酸盐去除量的38%-96%,DNRA过程也是长江口主要的硝酸盐削减过程,占总硝酸盐还原量的3%-45%,与反硝化和DNRA过程相比,厌氧氨氧化过程仅占总硝酸盐还原量的1%-36%。通过反硝化和厌氧氨氧化过程,能够削减每年输入到长江口活性氮总量的25%。
[Abstract]:Nitrogen is one of the key biogenic factors affecting estuarine and coastal water environment ecosystem. In the past few decades, due to the intensification of human activities, the amount of active nitrogen emitted into the environment has increased by 120. It has become a hot issue in the world to study the process of nitrogen transport and transformation near the estuary and coast. Excessive input of active nitrogen has caused a series of ecological and environmental problems to estuarine and coastal ecosystems, including changes in population structure, reduction of biodiversity, formation of hypoxic regions and frequent outbreaks of blue algae red tide. Therefore, further research on nitrogen cycling in estuarine and coastal environment can deepen the theoretical understanding of the process of nitrogen cycling in estuaries and coastal areas, and understand the fate of nitrogen and have important practical significance in controlling the increasingly serious problem of nitrogen pollution. The process of nitrate dissimilation reduction in water environment mainly includes denitrification, anaerobic ammonia oxidation and nitrate dissimilatory reduction to ammonia DNRA. different processes play different roles in nitrogen conversion and fate. Denitrification and anaerobic ammonia oxidation are the most important processes of active nitrogen reduction in water. In the process of DNRA, the fate of nitrate is different from denitrification and anaerobic ammonia oxidation. In the process of DNRA, nitrate is converted to ammonium salt, which remains in water environment system in a more bioavailability form. A deeper understanding of nitrogen transference and cycling in estuarine and coastal areas is of great value and guidance in evaluating the potential environmental impacts of estuarine ecosystems and coordinating environmental protection and sustainable development. In this paper, the denitrification, anaerobic ammonia oxidation and DNRA potential rate in sediments of Yangtze Estuary were studied by sampling mud experiment and isotope tracer technique. The effects of sediment environmental factors on the process of nitrate reduction were investigated. The contribution of denitrification and anaerobic ammonia oxidation and the effect of DNRA process on the denitrification process were estimated. The main results are as follows: denitrification, anaerobic ammonia oxidation and DNRA potential rates of bottom sediments in the Yangtze Estuary are 0.06-4.51 pmol N kg-1 h-1n 0.01-0.52 渭 mol N kg-1 h-1 and 0.03-0.89 渭 mol N kg-111-1, respectively. Denitrification in sediment vegetation cover area of Yangtze Estuary tidal flat, The rates of anaerobic ammonia oxidation and DNRA were 3.63-10.68 pmol N kg-1 h-1n 0.03-0.71 渭 mol N kg-1 h-1 and 0.87-5.57 渭 mol N kg-1 h-1, respectively, while the rates of non-vegetation coverage were 1.81-6.22 pmol N kg-1 h-1n 0.03-0.23 pmol N kg-1 h-1 and 0.14-2.98 pmol N kg-1 h-1.2. The effects of sulphide, organic carbon and Fe (鈪，

本文编号：1796990