Collaborative Research: Degrading offshore permafrost as a source of methane on the East Siberian Arctic Shelf

合作研究：近海永久冻土退化作为东西伯利亚北极大陆架甲烷的来源

• 批准号: 0908788
• 负责人: Samantha Joye
• 金额: $ 55.85万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0908788&HistoricalAwards=false
• 关键词: Collaborative; Research; Degrading; offshore; permafrost

The Arctic region contains a huge amount of organic carbon, referred to as the Arctic Carbon Hyper Pool, within the Arctic Ocean sedimentary basin. This area has the highest documented rates of coastal sedimentation with annual accumulation rates of about 10 million metric tons organic C per year, which approximately equals the amount of sediment accumulated over the entire pelagic zone of the World Ocean. Due to the specific features of sedimentation and lithogenesis in this area, much of this organic carbon survives decomposition, and is buried within seabed sediments. These sediments are frozen annually or seasonally, representing a substantial reservoir of potentially labile organic carbon. Global warming in the arctic region is predicted to be substantial, and possibly rapid, in next few decades. Upon the melting of permafrost, old stored carbon will be reintroduced into the modern carbon biogeochemical cycle, possibly acting as a strong source of methane to the overlying water and potentially the atmosphere. Additionally, extremely large amounts of more ancient (Pleistocene) methane are trapped as gas hydrates within and beneath the permafrost. This research aims to elucidate the present and future methane flux potential of sediments and permafrost in regions of the East Siberian Arctic Shelf. As a result of global warming, seafloor permafrost along the East Siberian Arctic Shelf may experience a pronounced change in thermal regime. Increased temperature may affect permafrost in several ways, ultimately leading to its degradation and enhanced CH4 release. An international, interdisciplinary research team will determine the distribution and stability of permafrost on the East Siberian Arctic Shelf and evaluate this area as a methane source to the arctic region. Cores from eleven locations will be obtained using dry drilling techniques. Rates of biological methane production and consumption (oxidation) will be quantified in permafrost and sediments at in situ and elevated temperatures. Natural abundance stable carbon and hydrogen isotope measurements will be used to quantify the age and source of methane collected from different sites and depths. These data will be used as input to numerical models, which will be developed to describe the thermodynamic and biogeochemical aspects of permafrost methane dynamics. Using field data and modeling, the current and future potential release of methane from offshore permafrost will be determined and a methane budget for the East Siberian Arctic Shelf will be constructed.

北极区域中包含大量有机碳，被称为北极海洋沉积盆地内的北极碳超池。该地区的沿海沉积率最高，每年约1000万吨有机c，这大约等于在世界海洋整个上层区域中积累的沉积物量。由于该区域沉积和岩性发生的特定特征，这种有机碳的大部分生存分解，并埋在海底沉积物中。这些沉积物每年或季节性冷冻，代表了潜在不稳定有机碳的大量储层。预计在接下来的几十年中，北极地区的全球变暖将是巨大的，甚至可能是迅速的。多年冻土融化后，旧储存的碳将被重新引入现代碳生物地球化学循环中，这可能是上覆水的强大甲烷来源，并可能是大气。此外，将大量更古老的（更新世）甲烷被困在多年冻土中和下方的气体中。这项研究旨在阐明东西伯利亚北极货架地区的沉积物和多年冻土的当前和未来甲烷通量潜力。由于全球变暖，东西伯利亚北极架子沿着沿着东西伯利亚北极货架的海底长期冻土可能会发生明显变化的热度状态。温度升高可能会以多种方式影响多年冻土，最终导致其降解并增强CH4的释放。一个国际，跨学科的研究团队将确定在东西伯利亚北极货架上永久冻土的分布和稳定性，并评估该地区作为北极地区的甲烷源。使用干钻技术将获得11个位置的核心。生物甲烷的产生和消耗率（氧化）将在原位和温度升高的多年冻土和沉积物中进行量化。自然丰度稳定的碳和氢同位素测量将用于量化从不同位点和深度收集的甲烷的年龄和来源。这些数据将用作数值模型的输入，该数据将开发以描述多年冻土甲烷动力学的热力学和生物地球化学方面。使用现场数据和建模，将确定甲烷从多年冻土的当前和未来潜在释放，并将建造东西伯利亚北极架子的甲烷预算。