Collaborative Research: RAPID: Quantifying and characterizing the origin of Arctic Ocean methane from the Alaska continental shelf to the North Pole

甲烷在地球大气中相对稀少，但在全球碳循环和气候变化中起着重要作用。因此，更好地了解甲烷排放的自然来源的分布和行为，以及它们在不断变化的气候中如何变化，是关键。在北极，大量的甲烷储藏库目前被困在北冰洋大陆架上的永久冻土（冻土）或天然气水合物（一种结构中含有甲烷的冰状物质）中。随着北极变暖，永久冻土和天然气水合物可能会降解，向大气释放更多的甲烷。这个项目是美国对国际北极综合调查（SAS）的一部分贡献，通过测量从阿拉斯加北部到北极的北冰洋中的甲烷，来确定从这些自然来源释放的北极甲烷的速率是否受到当前变暖的影响。该团队特别关注海底释放的甲烷到达水面并增加大气甲烷的数量。该小组正在与更大的美国SAS项目分享甲烷数据和其他结果，并向社区大学的学生讲授航海研究方法和气候变化。该项目正在测试一个假设，即北冰洋变暖可能加速了永久冻土中甲烷的释放，以及大陆架和斜坡沉积物中天然气水合物的分解。研究小组正在测量水柱中溶解的甲烷浓度和稳定的同位素，并沿着阿拉斯加大陆架向北的样带连续测量空气中的甲烷。研究小组成员正在利用甲烷13C和2H稳定同位素研究甲烷的来源和控制甲烷存在的过程。空气中甲烷的团块同位素正在对选定的样品进行分析，这些样品被确定为北极系统中可能的甲烷末端成员。该项目是美国对国际北极综合调查（SAS）的贡献，并为未来北极条件的测量提供基线。北极盆地稳定同位素2H-CH4的测量是首次在北极深水中进行的，这极大地提高了我们对北极甲烷循环的认识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Methane is relatively rare in Earth’s atmosphere but plays a significant role in the global carbon cycle and climate change. It is therefore key to better understand the distribution and behavior of natural sources of methane emissions and how both may change in an evolving climate. In the Arctic, large reservoirs of methane are currently trapped as permafrost (frozen soil) or gas hydrates (an ice-like substance that contains methane in its structure) on Arctic Ocean continental shelves. As the Arctic warms, permafrost and gas hydrates may degrade, releasing more methane to the atmosphere. This project, part of the United States’ contribution to the international Synoptic Arctic Survey (SAS), is determining whether rates of Arctic methane release from those natural sources are being affected by the present warming by measuring methane in Arctic Ocean from northern Alaska to the North Pole. The team is focusing especially on how much methane released from the seafloor reaches the water surface and adds to atmospheric methane. The team is sharing methane data and other results with the larger US SAS effort and teaching community college students about seagoing research methods and climate change. This project is testing the hypothesis that a warming Arctic Ocean may have accelerated the release of methane from permafrost and gas hydrate dissociation in shelf and slope sediments. The research team is measuring water column dissolved methane concentrations and stable isotopologues, as well as continuous measurements of methane in air underway along a transect from the Alaska Shelf northward. The team members are investigating the sources and processes controlling the presence of methane using methane 13C and 2H stable isotopes. Clumped isotopes of methane in air are being analyzed on selected samples identified as possible methane endmembers in the Arctic system. The project is a US contribution to the international Synoptic Arctic Survey (SAS) and is providing a baseline for measurements in the future of Arctic conditions. The measurement of the stable isotope 2H-CH4 in the Arctic Basin is the first performed in deep Arctic waters and is greatly improving our understanding of the Arctic methane cycle.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.