本文選題：反硝化 + 厭氧氨氧化��； 參考：《華東師范大學》2016年碩士論文

【摘要】：氮是影響河口近海岸水環(huán)境生態(tài)系統(tǒng)的關(guān)鍵生源要素之一。在過去的幾十年間,由于人類活動加劇,排放到環(huán)境中的活性氮含量增加了120%,開展河口近海岸氮素的遷移轉(zhuǎn)化過程研究成為當今國際上熱點科學問題。過量的活性氮輸入給河口近海岸生態(tài)系統(tǒng)造成了一系列生態(tài)環(huán)境問題,包括種群結(jié)構(gòu)的變化、生物多樣性的減少、低氧區(qū)域的形成以及藍藻赤潮頻繁爆發(fā)。因此,深入開展河口海岸環(huán)境氮循環(huán)研究,可加深對河口近海岸氮循環(huán)轉(zhuǎn)化過程的理論認識,并了解氮素的歸宿以及對于控制日益嚴峻的氮污染問題具有重要的現(xiàn)實意義。水環(huán)境中的硝酸鹽異化還原過程主要包括反硝化、厭氧氨氧化和硝酸鹽異化還原成氨(DNRA)過程,不同的過程在氮素的轉(zhuǎn)化和歸宿中扮演著不同的角色。反硝化與厭氧氨氧化是水體中最為重要的活性氮削減過程,將硝酸鹽或者氨氮轉(zhuǎn)化為氮氣,永久性的脫離水體。在DNRA過程中,硝態(tài)氮的歸宿不同于反硝化和厭氧氨氧化,在DNRA過程中硝酸鹽轉(zhuǎn)換為銨鹽,以一種更具生物有效性的形式繼續(xù)殘留在水環(huán)境系統(tǒng)中。深入了解氮素在河口海岸地區(qū)的遷移轉(zhuǎn)化和循環(huán)過程,對于評價河口生態(tài)系統(tǒng)的潛在環(huán)境影響效應、協(xié)調(diào)環(huán)境保護與可持續(xù)發(fā)展具有重要的應用價值和指導意義。本文以長江口作為典型研究區(qū),采樣泥漿實驗結(jié)合同位素示蹤技術(shù)研究了長江口沉積物中反硝化、厭氧氨氧化和DNRA潛在速率,探究沉積物環(huán)境因子對硝酸鹽異化還原過程的影響,估算反硝化、厭氧氨氧化過程的脫氮貢獻率以及DNRA過程對于脫氮過程的影響。取得主要研究成果如下：(1)長江口底層沉積物的反硝化、厭氧氨氧化以及DNRA潛在速率的范圍分別是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。長江口潮灘沉積物植被覆蓋區(qū)的反硝化、厭氧氨氧化和DNRA速率分別是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;而非植被覆蓋區(qū)域的速率為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)長江口沉積物中的反硝化速率變化主要受溫度、硫化物、有機碳以及Fe(Ⅱ)影響；溫度和硫化物對于沉積物中的厭氧氨氧化速率的分布存在明顯的影響作用；影響沉積物中DNRA速率的主要環(huán)境因子是硫化物、Fe(Ⅱ)和有機碳。(3)反硝化是長江口硝酸鹽削減的最主要過程,占總的硝酸鹽去除量的38%-96%,DNRA過程也是長江口主要的硝酸鹽削減過程,占總硝酸鹽還原量的3%-45%,與反硝化和DNRA過程相比,厭氧氨氧化過程僅占總硝酸鹽還原量的1%-36%。通過反硝化和厭氧氨氧化過程,能夠削減每年輸入到長江口活性氮總量的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，

本文編號：1796990