养殖水体温室气体的溶存与排放及其影响因素研究

发布时间：2018-03-27 21:39

本文选题：养殖水体　切入点：氧化亚氮(N2O)　出处：《华中农业大学》2015年硕士论文

【摘要】：随着大气中氧化亚氮(N2O)、甲烷(CH4)和二氧化碳(CO2)等温室气体含量的日益增加,促使越来越多的N2O、CH4和CO2溶存到水体中;与此同时,水体也向大气释放了更多的N2O、CH4和CO2,使得水体成为了最重要的源与汇之一。虽然养殖水体仅占全球水体很小一部分的水域面积,由于它受人为扰动大的原因,养殖水体仍在全球碳、氮循环的过程中仍起到不可或缺的作用,是全球温室气体源与汇的重要组成部分之一。但目前养殖水体温室气体的溶存及排放的现状仍不明确。本研究于2014年1月至2014年11月期间,以华中农业大学水产学院二号教学基地的养殖水体为对象,用气相色谱法测定N2O、CH4和CO2的溶存浓度和交换通量,并同步测定水体的温度、p H和可溶性碳、氮等环境因素,研究养殖类水体中温室气体的溶存、交换通量以及环境因子对前两者的影响,旨在为我国养殖水体温室气体的排放与减排提供依据。主要研究结果如下:(1)养殖水体中溶存的温室气体在不同深度水体中浓度分布各具特征:N2O浓度在表层、中间层和底层这三个深度层分布较均匀,其浓度的变化范围为:0.33~15.79μg L-1;CH4则普遍以底层浓度较高,以秋季时最为显著,其浓度变化范围为:1.11~84.09μg L-1;CO2浓度则以底层浓度较低,其整体浓度变化范围为:840~10910μg L-1。(2)养殖水体中三种温室气体总体上均处于饱和至过饱和状态。其中,N2O和CO2溶解饱和度在不同深度上没有显著差异。夏季时N2O溶解饱和度稍高于其他三季,人为管理等因素会对养殖水体CO2饱和度产生影响。在夏季和秋季时,底层的CH4溶解饱和度要显著高于表层和中间层,且养殖水体CH4溶解饱和度与湖泊变化范围最为接近。(3)总体上来说,养殖水体是大气N2O、CH4和CO2的源。其气—水界面N2O、CH4和CO2交换通量的变化范围分别在:-0.033~0.462μg m-2 h-1,0.014~6.231μg m-2 h-1和-15.372~2395.543μg m-2 h-1之间。其中,N2O的排放高峰出现在夏季,而CH4和CO2的排放高峰在夏季和秋季。相对于平原河流、野生湿地、湖泊源头溪流水体和浅水池塘以及水库来说,养殖水体对N2O和CO2的吸收较小。相对于浅水池塘来说,养殖水体对CH4的吸收较小,但大于部分地区的富营养湖泊。(4)养殖水体中溶存的N2O是通过硝化—反硝化耦合作用产生的,其中硝化作用对N2O的形成贡献最大,NO3-和DTN(可溶性总氮)是控制水体中N2O产生和释放的主要环境影响因子;当水体中SO42-浓度过高时会抑制CH4产生,而在缺氧状态下水体中可溶性无机碳的增加会促进CH4的排放;p H是控制水体中CO2溶存含量多少的主要环境因子;在水体中DO(溶解氧)充足情况下,CH4在从沉积物向水面扩散的过程中有一部分会被氧化成CO2释放到大气中。
[Abstract]:With the increasing contents of such greenhouse gases as nitrous oxide (N _ 2O _ 4), methane (Ch _ 4) and CO _ 2 (CO _ 2) in the atmosphere, more and more N _ 2O _ (2) Ch _ (4) and CO2 are dissolved in water bodies; at the same time, Water also releases more N2O-CH4 and CO2 to the atmosphere, making it one of the most important sources and sinks. Aquaculture waters still play an indispensable role in the global carbon and nitrogen cycle. Is an important component of global greenhouse gas sources and sinks. However, the current status of greenhouse gas dissolution and emissions in aquaculture water remains unclear. This study was conducted from January 2014 to November 2014, The dissolved concentration and exchange flux of N _ 2O _ 4 Ch _ 4 and CO2 were determined by gas chromatography, and the temperature, pH, soluble carbon, nitrogen and other environmental factors in the water were measured simultaneously, taking the culture water body of the No. 2 teaching base of Huazhong Agricultural University as the object, and the gas chromatography was used to determine the dissolved concentration and exchange flux of N _ 2O _ 4 and CO2. To study the effects of greenhouse gas solubilization, exchange flux and environmental factors on the first two types of water, The main results are as follows: (1) the concentration distribution of greenhouse gases dissolved in aquaculture water bodies in different depths is characterized by the concentration distribution of N 2O in the surface layer. In the middle layer and the bottom layer, the distribution of the three depth layers is more uniform. The range of concentration variation is: 0.33 ~ 15.79 渭 g / L ~ (-1) Ch _ (4), which is generally higher in the bottom layer, especially in autumn, and the change range of the concentration is in the range of: 1.11 ~ 84.09 渭 g / L ~ (-1) CO _ (2), but the lowest is in the bottom layer. The whole concentration range is 10910 渭 g / L ~ (2)) the three greenhouse gases in the aquaculture water are all saturated to supersaturation, and there is no significant difference between the dissolved saturation of N _ 2O and CO2 in different depth. In summer, the saturation of N _ 2O solution is not significant. Slightly higher than the other three seasons, In summer and autumn, the saturation of CH4 dissolved in the bottom layer was significantly higher than that in the surface layer and the middle layer. Moreover, the CH4 saturation of aquaculture water is the closest to the range of lake variation. (3) on the whole, The exchange fluxes of N _ 2O _ 2 Ch _ 4 and CO2 at the air-water interface range from 0: 0.033 to 0.462 渭 g m-2 h-1 0.014 渭 g m-2 h-1 and -15.372 渭 g m-2 h-1 and -15.372 渭 g m-2 h-1, respectively, and the peak of N2O emission occurs in summer, and N2O-CH4 and CO2 exchange fluxes in the air-water interface range from 6.231 渭 g m-2 h-1 to -15.372U 2395.543 渭 g m-2 h-1, respectively. The peak emission of CH4 and CO2 is in summer and autumn. Compared with plain rivers, wild wetlands, source streams, shallow ponds and reservoirs, the uptake of N2O and CO2 in aquaculture water is relatively small. The uptake of CH4 in culture water was small, but larger than that in eutrophic lake. 4) the dissolved N 2O in culture water was produced by the coupling of nitrification and denitrification. Nitrification contributes the most to the formation of N2O. Nitrification is the main environmental factor to control the production and release of N2O, and when the concentration of SO42- in water is too high, it will inhibit the production of CH4. Under the condition of hypoxia, the increase of soluble inorganic carbon in the water will promote the discharge of CH4, which is the main environmental factor to control the amount of dissolved CO2 in the water. When do (dissolved oxygen) is sufficient in water, some of CH4 is oxidized to CO2 and released into the atmosphere as it diffuses from sediment to water.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X714

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