上海城市河网沉积物硝酸盐异化还原过程及其环境影响因素研究

发布时间：2018-01-11 18:21

本文关键词：上海城市河网沉积物硝酸盐异化还原过程及其环境影响因素研究　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：氮是影响水生生态系统的环境恶化的主要因素之一。近些年,由于化石燃料的燃烧、生活污水排放和工业排放等人类活动导致大量氮素排放进入城市河流,这些人为输入的活性氮进入到城市河流环境。进入到河流环境的氮以硝态氮的形体存在于河流水环境中。河流环境中氮的高度富集造成了水环境质量恶化、水体酸化和生物多样性减少等一系列的生态环境问题,给河流生态环境造成严重威胁。城市河流水环境氮高度富集现象已引起人们的广泛关注,也是当今城市环境研究的热点科学问题。然而,现阶段关于城市河流氮循环及活性氮去除机制的研究鲜有报道。因此,开展城市河流沉积物氮的削减途径、归宿和生态环境效应研究,对加强城市河流氮循环过程的作用机制深入认识具有重要的意义。基于此,本研究以上海城市河网为研究对象,研究上海城市河网沉积物硝酸盐异化还原过程,揭示上海城市河网氮素污染状况和硝态氮去除削减机制及其归宿。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为铵(DNRA)过程。其中反硝化和厌氧氨氧化是分别将硝酸盐和氨氮通过微生物作用转化为氮气脱离水体,长期以来被认为是自然环境中最重要的活性氮去除过程。DNRA过程不同于反硝化和厌氧氨氧过程,它是将硝酸盐转化为生物可利用性更高的铵盐,进而继续留存在自然环境中,在氮转化和归宿中也具有非常重要的作用。本研究采用同位素示踪技术结合泥浆培养试验上海城市河网沉积物反硝化、厌氧氨氧化和DNRA过程及其影响因素,并探讨硝酸盐异化还原生态效应。主要研究成果包括以下几方面:(1)上海城市河网沉积物硝酸盐异化还原过程具有明显的季节变化和空间差异特征。冬季,反硝化潜在速率为0.19-16.9 nmol N g-1 h-1(以干重计),夏季为1.98-987 nmol N g-1 h-1;厌氧氨氧化潜在速率范围冬季和夏季分别为0.0404-23.7 nmol N g-1 h-1 和 0.243-12.9nmol N g-1 h-1;DNRA 冬季和夏季的潜在速率范围分别为0-7.28 nmol N g-1 h-和0-10.3 nmol N g-1 h-1。研究区,夏季反硝化和DNRA过程速率高于冬季,而冬季的厌氧氨氧化速率冬季速率高于夏季。(2)上海城市河网沉积物硝酸盐异化还原过程受多种环境因子的影响,溶解氧、总有机碳、硝态氮、氨氮、硫化物和活性铁对三种硝酸盐还原过程具有显著的影响。其中,反硝化过程主要受到溶解氧、硝酸盐、二价铁、三价铁、硫化物和总有机碳影响;厌氧氨氧化过程与氨氮、三价铁和溶解氧显著相关;硝态氮含量和C/N是DNRA过程的主要影响因素。(3)上海城市河网沉积物的反硝化和厌氧氨氧化过程在总硝酸盐异化还原过程中的比例范围为11.5-99.5%和0.343-81.6%,DNRA过程在硝酸盐还原过程贡献率只有0-52.3%。三种过程对硝酸盐异化还原量的平均值来看,反硝化、厌氧氨氧化和DNRA贡献率分别为50.2%、40.5%和9.3%。相较于DNRA过程,反硝化与厌氧氨氧化是上海城市河网沉积物中主要的硝酸盐削减过程。经估算,上海城市河网沉积物反硝化和厌氧氨氧化过程的脱氮量约为每年8.86×104t和4.45× 104t,总脱氮量为1.33× 105t,占河流每年氮输入量的20.1%。
[Abstract]:Nitrogen is one of the main factors affecting the aquatic ecosystem environment deterioration. In recent years, due to the burning of fossil fuels, sewage emissions and industrial emissions and other human activities lead to a large number of nitrogen discharged into the river city, the anthropogenic input of reactive nitrogen into the environment into the river. The river city environment of nitrogen in nitrate form exists on the river water environment in river environment. Nitrogen in high concentration caused the deterioration of water environmental quality, water acidification and the loss of biodiversity and a series of ecological environment problems, causing a serious threat to the ecological environment of the river. The city river water environment nitrogen high enrichment phenomenon has aroused widespread concern and hot science problem is the city study on the environment. However, few studies on city river at this stage the nitrogen cycle and the activity of nitrogen removal mechanisms reported. Therefore, to carry out the city of river sediment Cut the way nitrogen, study on the effect of fate and ecological environment, strengthen the understanding of mechanism of city river nitrogen cycle has important significance. Based on this, this study takes Shanghai City River as the research object, the reduction process of Shanghai city river sediment nitrate dissimilation, revealed Shanghai city river pollution and nitrate nitrogen nitrogen removal mechanism and cut end. Dissimilatory nitrate reduction process including denitrification, anaerobic ammonium oxidation and reduction of nitrate to ammonium alienation (DNRA) process. The denitrification and anammox is respectively nitrate and ammonia nitrogen by microorganisms into nitrogen from water, has long been considered the most important activity of nitrogen the natural environment in the removal process of.DNRA is different from the process of denitrification and anaerobic ammonia oxidation process, it is the conversion of nitrate to bioavailable ammonium salt into the higher. And continue to exist in the natural environment, but also has a very important role in the nitrogen transformation and fate. In this study by using isotope tracer technique combined with mud cultivation test of Shanghai city river sediment denitrification, factors of anaerobic ammonia oxidation and DNRA process and its effects, and to explore the ecological effects of dissimilatory nitrate reduction. The main results include the following aspects: (1) Shanghai city river sediments dissimilatory nitrate reduction process with different distinct seasonal and spatial characteristics. In winter, the denitrification rate of 0.19-16.9 nmol N g-1 potential H-1 (dry weight), 1.98-987 nmol N g-1 H-1 in summer; anaerobic ammonia oxidation potential rate range in winter and summer respectively 0.0404-23.7 nmol N g-1 H-1 and 0.243-12.9nmol N g-1 H-1; the potential range of DNRA rate in winter and summer were 0-7.28 nmol N g-1 h- and 0-10.3 nmol N g-1 h-1. in study area. Denitrification and DNRA rate is higher than that in winter, while in winter, the anaerobic ammonia oxidation rate is higher than that in summer. The winter rate (2) of Shanghai city river sediments dissimilatory nitrate reduction process is affected by many environmental factors, dissolved oxygen, total organic carbon, nitrate nitrogen, ammonia nitrogen, has a significant effect on three kinds of iron sulfide and activity the nitrate reduction process. The denitrification process is mainly affected by dissolved oxygen, nitrate, ferric iron, two iron sulfide and total organic carbon; anaerobic ammonia oxidation process and ammonia nitrogen were significantly related to ferric iron and dissolved oxygen; the nitrate nitrogen content and C/N are the main factors affecting the DNRA process (3). Shanghai city river sediment denitrification and anammox process in dissimilatory nitrate reduction process in the ratio range of 11.5-99.5% and 0.343-81.6%, DNRA during the reduction process of the contribution rate of only 0-52.3%. three in the process of nitrate nitrate The average amount of salt dissimilatory reduction, denitrification, anaerobic ammonium oxidation and DNRA contribution rate were 50.2%, 40.5% and 9.3%. compared with DNRA process, denitrification and anaerobic ammonium oxidation is the main process of nitrate reduction in Shanghai city river sediments. It is estimated that the denitrification capacity of Shanghai city river sediment denitrification and anaerobic the ammonia oxidation process was approximately 8.86 * 104t and 4.45 * 104t, the total nitrogen amount to 1.33 * 105T, accounting for the annual n input 20.1%. River

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

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