若尔盖高寒泥炭湿地甲烷排放特征研究

发布时间：2018-03-06 21:26

本文选题：甲烷排放　切入点：高寒泥炭　出处：《西北农林科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：甲烷(CH4)是仅次于二氧化碳的重要温室气体,其在百年尺度上的增温潜势是二氧化碳的28倍,其源和汇机理的认知引起重要关注。高寒泥炭湿地是重要的大气甲烷排放源,但由于高寒湿地非生长季的气候条件极其恶劣,过去的原位观测研究大多集中在生长季,致使迄今仍对季节性冻土区高寒泥炭湿地尤其是非生长季CH4排放缺乏充分认识。本研究以地处青藏高原东北部的若尔盖地区典型湿地为例,采用静态暗箱-气相色谱人工观测方法,开展了跨越冬、春季和初夏季连续9个月的原位观测研究,试图了解该湿地CH4排放特征及非生长季排放的相对重要性。结果与初步结论如下:1)整个观测期间湿地通量平均值介于0.1~1.0 mg C m-2 h-1之间;2)该湿地在非生长季也有较强的CH4排放,且非生长季CH4通量的温度响应系数Q10(18.1~29.8)远远大于在生长季(1.4~2.2),这意味着非生长季的CH4排放对气候变暖更敏感得多;3)结合其他生长季的观测结果,对观测数据的外推估计,该湿地的CH4年排放量约为30 kg C ha-1 yr-1,其中非生长季的贡献率高达50%以上;4)观测期的CH4通量具有明显季节变化,可解释为温度季节变化、土壤冻结与消融过程、水位(或土壤湿度)季节动态和植物生长节律等共同作用的结果;5)观测期的CH4通量还在构成湿地景观的三种微地形之间呈现出显著差异,即凸起处的排放相对最弱,凹陷处居中,二者的过渡带相对最强(p0.01),它们对整个湿地排放量的贡献率依次估计为大约22%、35%和43%,这种空间差异性可解释为水位(或土壤湿度)、植物分布和土壤有机质含量等因素的空间差异所致。不过,本研究中原位观测的持续时间相对较短,因而上述结果或结论能否在年度或更长时间尺度上重现,还需要长期连续观测研究加以检验。
[Abstract]:CH4) is an important greenhouse gas second only to carbon dioxide, and its warming potential is 28 times that of carbon dioxide on a century-scale scale. The understanding of the source and sink mechanism of CH4 is of great concern. The alpine peat wetland is an important source of atmospheric methane emissions. However, due to the extremely bad climatic conditions in the non-growing season of the alpine wetland, most of the in situ observation studies in the past focused on the growing season. As a result, there is still a lack of sufficient understanding of CH4 emissions in seasonal permafrost alpine peat wetlands, especially in non-growing seasons. This study takes the typical wetland in Ruoergai region, which is located in the northeast of the Qinghai-Tibet Plateau, as an example. In situ observation for 9 consecutive months spanning winter, spring and early summer was carried out by means of static dark box and gas chromatography artificial observation method. This paper attempts to understand the characteristics of CH4 emission and the relative importance of non-growth season emissions in this wetland. The results and preliminary conclusions are as follows: 1) the mean value of wetland flux during the observed period is between 0.1 and 1.0 mg / cm ~ (-2) h ~ (-1). The wetland also has strong CH4 emission in non-growth season. Moreover, the temperature response coefficient of CH4 flux in non-growing season is much higher than that in growing season, which means that CH4 emission in non-growing season is much more sensitive to global warming.) combined with the observation results of other growing seasons, extrapolation of observed data is obtained. The annual CH4 emission of the wetland is about 30kg C ha-1 yr-1, in which the contribution rate of non-growth season is as high as 50% ~ (4)) the CH4 flux of the observed period has obvious seasonal variation, which can be explained as the seasonal variation of temperature, the process of soil freezing and ablation, and the process of soil freezing and ablation. The seasonal dynamics of water level (or soil moisture) and plant growth rhythm were the results of the observation period. The CH4 fluxes also showed significant differences among the three micro-landforms that make up the wetland landscape, that is, the discharge from the protrusions was the weakest. The depression is in the middle, Their contribution to the total wetland emissions is estimated to be about 22% 35% and 43% respectively. This spatial difference can be explained by water level (or soil moisture, plant distribution and soil organic matter content, etc.). But, The duration of in-situ observations in this study is relatively short, so whether the above results or conclusions can be reproduced on an annual or longer time scale still needs to be verified by long-term continuous observation studies.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X171

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