典型河流生态系统碳氮温室气体扩散传输研究

发布时间：2018-07-05 03:19

本文选题：甲烷 + 氧化亚氮　；参考：《安徽师范大学》2017年硕士论文

【摘要】：甲烷(CH_4)和氧化亚氮(N_2O)是仅次于二氧化碳(CO_2)的两种主要温室气体,可以与大气中的O_3、OH和CO等物质发生化学反应,影响全球气候变化。CH_4和N_2O对大气温室效应贡献率分别是15%和6%。截至2012年CH_4和N_2O浓度分别为1819 ppb和325.1 ppb,分别比工业革命时期高出160%和20%,目前仍然在持续增加。由于人类活动带来的河流系统中碳和氮的可利用性增加,河流生态系统的CH_4和N_2O释放量也相应增加。本文以国家重点基础研究发展计划项目“典型流域陆地生态系统—大气碳氮气体交换关键过程、规律与调控原理:数据综合分析与集成研究”(2012CB417106)为依托,选取亚热带典型农业小流域脱甲河4级河段(S1、S2、S3和S4)为研究对象,在测定河流表层水体中溶存CH_4和N_2O浓度的基础上,利用双层扩散模型法对河流表层水体水-气界面CH_4和N_2O的扩散通量进行估算。同时测定水体多项理化指标,探究环境因子对河流CH_4和N_2O产生及扩散的影响。本文主要结论包括以下几点:(1)在2015年4月至2016年1月研究期间,脱甲河表层水体溶存CH_4浓度和扩散通量有明显的时空分布特征,其范围在0.004~3.01μmol·L-1之间,均值(0.41±0.02)μmol·L-1;扩散通量在-0.33~317.67μg·m-2·h-1,均值(42.28±1.79)μg·m-2·h-1。由于受农业生产和畜禽养殖的双重影响,空间分布上,CH_4扩散通量随因土地利用方式变迁引起的河流污染负荷程度增加而升高,变化范围在(22.37±2.87)~(55.56±4.32)μg·m-2·h-1之间;在时间尺度上,脱甲河CH_4扩散通量夏季最高,冬季最低。相关分析发现,CH_4扩散通量与溶解有机碳(DOC)(r=0.47,p0.001)和盐度(r=0.46,p0.001)呈极显著正相关,与水温呈显著正相关(r=0.27,p0.01),与溶解氧(DO)呈极显著负相关(r=-0.49,p0.001).(2)脱甲河表层水体溶存N_2O浓度范围在0.005~7.37μmol·L-1之间,均值为(0.54±0.05)μmol·L-1;扩散通量在-1.11~1811.29μg·m-2·h-1之间,均值(130.10±12.04)μg·m-2·h-1。其中在早稻生长初期和早晚稻收割、栽种交替时段N_2O扩散通量达到高峰。空间上,N_2O排放通量表现为S1S4S3S2,S1级河段显著低于其他3级河段(p0.01)。相关分析表明,脱甲河表层水体N_2O扩散通量与铵态氮(NH4+-N)(r=0.87,p0.01)、硝态氮(NO3--N)(r=0.80,p0.01)、水温(r=0.57,p0.01)和DOC(r=0.46,p0.01)呈显著正相关,与DO(r=-0.50,p0.01)呈显著负相关。(3)脱甲河水体是大气CH_4和N_2O的重要来源。由于人类活动引起脱甲河流域土地利用类型的变迁导致河流系统中碳和氮的可利用性增加,加剧了河流CH_4和N_2O的产生与释放。研究表明:脱甲河农业小流域城镇及农业生产活动造成水体污染引起水体的高负荷碳氮浓度是造成CH_4和N_2O释放的主要原因,科学合理安排脱甲河流域农业生产活动对控制CH_4和N_2O释放具有重要意义。
[Abstract]:Methane (CH4) and nitrous oxide (N2O) are the two main greenhouse gases, which are only inferior to CO2 (CO2). They can react with the O _ 3H _ H and CO in the atmosphere. The contribution rates of Ch _ 4 and N _ 2O to the atmosphere Greenhouse Effect are 15% and 6%, respectively. As of 2012, CH4 and N2O concentrations were 1819 ppb and 325.1 ppb, respectively, which were 160% and 20% higher than during the Industrial Revolution, respectively, and are still increasing. As the availability of carbon and nitrogen in the river system increased due to human activities, the CH4 and N2O emissions from the river ecosystem increased accordingly. This paper is based on the National key basic Research and Development Program, "key processes, laws and Regulation principles of carbon and nitrogen Exchange in typical Watershed Terrestrial ecosystems: data Comprehensive Analysis and Integration Research" (2012CB417106). Based on the determination of CH4 and NSC2O concentrations in the surface water of the subtropical typical agricultural watershed, the fourth section of the Dega River (S1 + S2 + S3 and S4) was selected as the research object, and the concentration of Ch _ 4 and NSP _ 2O in the surface water of the river was determined. The diffusion fluxes of Ch _ 4 and N _ 2O at the water-gas interface of the surface water of rivers were estimated by using the double-layer diffusion model method. At the same time, the effects of environmental factors on the generation and diffusion of Ch _ 4 and N _ 2O in rivers were investigated. The main conclusions of this paper are as follows: (1) during the study period from April 2015 to January 2016, CH4 concentration and diffusion flux in the surface water of Dejia River showed obvious temporal and spatial distribution characteristics, with the range of 0.004 渭 mol L-1 and the mean value of 0.41 卤0.02 渭 mol L-1 and the diffusion flux of -0.33317.67 渭 g m-2 h-1and (42.28 卤1.79) 渭 g m-2 h-1respectively. Due to the dual effects of agricultural production and livestock and poultry breeding, the CH4 diffusion flux increased with the increase of river pollution load caused by changes in land use patterns, ranging from (22.37 卤2.87) 渭 g / m-2 h-1 to (55.56 卤4.32) 渭 g m-2 h-1, and on a time scale. The diffusion flux of CH4 was the highest in summer and the lowest in winter. Correlation analysis showed that the diffusion flux of Ch _ 4 was significantly positively correlated with dissolved organic carbon (DOC) (r _ (0.47) p ~ (0.001) and salinity (r _ (0.46) P _ (0.001), and positively correlated with water temperature (r _ (0.27) p _ (0.01), and negatively correlated with dissolved oxygen (do) (r ~ -0.49p ~ (0.001). (_ (2) in the range of 0.0057.37 渭 mol ~ (-1) ~ (-1). The mean value was (0. 54 卤0. 05) 渭 mol L ~ (-1) and the diffusion flux was (130.10 卤12. 04) 渭 g m ~ (-2) h ~ (-1) between -1.11 ~ (11) 渭 g 路m ~ (-2) h ~ (-1). In the early stage of early rice growth and early and late rice harvest, the peak of N _ 2O diffusion flux was achieved during the alternate planting period. In space, the emission flux of N2O in S _ 1S _ 4S _ 3S _ 2N _ 1 reach was significantly lower than that in the other three levels (p 0.01). Correlation analysis showed that there was a significant positive correlation between N2O diffusion flux and ammonium nitrogen (NH _ 4-N), no _ 3 N (r _ (0.80) p _ (0.01), water temperature (r _ (0.57) P _ (0.01) and DOC (r _ (0.46) p _ (0.01) in the surface water of the deformable river, and a significant negative correlation with do (r _ (-0.50) P _ (0.01). (3) the demethylated river body was an important source of Ch _ 4 and N _ 2O in the atmosphere. Because of the change of land use types in Dejia River basin caused by human activities, the availability of carbon and nitrogen in the river system increased, and the generation and release of CH4 and N2O increased. The results show that the concentration of carbon and nitrogen in water body caused by water pollution caused by urban and agricultural production activities in the small agricultural watershed of Dejia River is the main cause of CH4 and NSP emission. Scientific and reasonable arrangement of agricultural production activities in Dejia River basin is of great significance to control CH4 and NSCO emission.
【学位授予单位】：安徽师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X511;X171.1

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