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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=686855
• 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，也是能够改变地球气候的有效温室气体。量化甲烷向大气的天然和人类释放是具有挑战性的，但为了使各国验证是否实现了减少温室气体排放的目标。 ***湿地，例如沼泽，羊毛，沼泽和沼泽是甲烷排放到大气中的最大自然来源。在工业前的时期，天然湿地是地球大气中甲烷的主要来源，并且继续是甲烷的主要多年生来源，甲烷形成了自然大气背景，在该背景上，人类甲烷排放叠加并必须辨别。甲烷中碳和氢的重量和轻度同位素的微妙差异可用于从不同来源（包括不同类型的湿地）中“指纹”排放。 可靠的识别来源增强了我们在区域和全球范围内量化排放源年度变化的能力。它还可以检测到来源的变化，例如像湿地这样的庞大的全球生态系统是否以可能进一步增加地球大气中甲烷和二氧化碳量的方式对气候变化做出反应。 ***湿地同位素变化的自然模式仍在出现，特别是对于氢同位素，由于分析挑战，迄今为止尚未对此进行广泛研究。 该研究计划将采用新的激光仪器（加拿大的第一种类型），在湿地的地下及其对大气的排放量同时测量碳和氢同位素组成。将确定甲烷排放的同位素组成与湿地类型之间的关系。环境变量的影响以及改变同位素比在甲烷中改变同位素比的作用也将被表征。数据将集成到全球模型中，以完善湿地对甲烷大气浓度的贡献的估计，并提高人们对湿地在影响地球大气中甲烷增长速率年度变化速度变化中所起的作用的理解。从这些重要的自然生态系统中对排放的更详细的了解将使从人类活动中释放甲烷的释放，特别是生物学来源，因为目前无法使用碳同位素的明确量化。基于稳定的碳和氢同位素的双同位素方法的开发将提供较少模棱两可的来源特征，并有助于完善全球甲烷周期预算。