Wetland contribution to interannual variability in atmospheric methane growth rate

湿地对大气甲烷增长率年际变化的贡献

• 批准号: RGPIN-2018-04743
• 负责人: Hornibrook, Edward
• 金额: $ 2.62万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653844
• 关键词: Wetland; contribution; interannual; variability; atmospheric

Methane (CH4) is an important energy source for human society but also a potent greenhouse gas capable of altering Earth's climate. Quantifying natural and human release of methane to the atmosphere is challenging but necessary in order for nations to verify that targets are being met for reducing greenhouse gas emissions. *** Wetlands such as bogs, fens, marshes and swamps are the largest natural source of methane emissions to the atmosphere. During pre-industrial times, natural wetlands were the dominant source of methane in Earth's atmosphere and continue to be a key perennial source of methane that forms the natural atmospheric background on which human methane emissions are superimposed and must be discerned. Subtle differences in the quantities of heavy and light isotopes of carbon and hydrogen in methane can be used to 'fingerprint' emissions from different sources, including different types of wetland. Reliable identification of sources enhances our ability to quantify year-to-year changes in emission sources both regionally and globally. It also enables detection of change in sources such as whether vast global ecosystems like wetlands are responding to climate change in a manner that may further increase the amount of methane and carbon dioxide in Earth's atmosphere. *** Natural patterns of isotopic variation in wetlands are still emerging, in particular for hydrogen isotopes, which have not been studied extensively to date because of analytical challenges. This program of research will employ new laser instrumentation, the first of its type in Canada, to measure both carbon and hydrogen isotope compositions simultaneously in the subsurface of wetlands and their emissions to the atmosphere. Relationships between the isotope composition of methane emissions and wetland type will be determined. The influence of environmental variables and the role of gas transport process that alter isotope ratios in methane also will be characterized. The data will be integrated into global models to refine estimates of the contribution of wetlands to the atmospheric concentration of methane and to improve understanding of the role that wetlands play in influencing year-to-year changes in the rate at which methane is increasing in Earth's atmosphere. A more detailed knowledge of emissions from these important natural ecosystems will enable more accurate quantifications of methane release from human activities, in particular, biological sources because their emissions at present cannot be ‘fingerprinted' unambiguously using only carbon isotopes. Development of a dual isotope approach based upon both stable carbon and hydrogen isotopes will provide less ambiguous source signatures and help to refine the global methane cycle budget.

甲烷（CH4）是人类社会的重要能源，也是一种能够改变地球气候的温室气体。量化自然和人类释放到大气中的甲烷是一项挑战，但对于各国核实减少温室气体排放的目标是否得到实现是必要的。* 沼泽、沼泽、沼泽和沼泽等湿地是向大气排放甲烷的最大自然来源。在前工业时代，天然湿地是地球大气中甲烷的主要来源，并继续成为甲烷的主要常年来源，形成了人类甲烷排放叠加的自然大气背景，必须加以识别。甲烷中碳和氢的重同位素和轻同位素数量的细微差异可以用来识别不同来源的排放，包括不同类型的湿地。 可靠的来源识别增强了我们量化区域和全球排放源逐年变化的能力。它还可以检测来源的变化，例如湿地等巨大的全球生态系统是否正在以可能进一步增加地球大气中甲烷和二氧化碳含量的方式对气候变化做出反应。* 湿地中同位素变化的自然模式仍在出现，特别是氢同位素，由于分析方面的挑战，迄今尚未进行广泛研究。 该研究方案将采用加拿大第一种新型激光仪器，同时测量湿地地下的碳和氢同位素组成及其向大气的排放。将确定甲烷排放的同位素组成与湿地类型之间的关系。环境变量的影响和气体运输过程中的作用，改变甲烷同位素比的特点也将。这些数据将被纳入全球模型，以完善湿地对大气中甲烷浓度的贡献的估计，并更好地了解湿地在影响地球大气中甲烷增加速度的逐年变化方面所发挥的作用。更详细地了解这些重要的自然生态系统的排放量，将能够更准确地量化人类活动，特别是生物来源的甲烷释放量，因为它们的排放量目前不能明确地使用碳同位素。基于稳定的碳和氢同位素的双同位素方法的发展将提供更少的模糊源签名，并有助于完善全球甲烷循环预算。