The Carbon Balance of Arctic Tundra in Response to Permafrost Thawing: Using Radiocarbon to Detect the Loss of Old Soil Carbon

在最后一次大冰原消融之后，高纬度生态系统中已经积累了高达4500亿吨的土壤碳。最近的研究表明，这些生态系统可能不再在土壤中积累碳，在某些情况下，可能会将储存的碳流失到大气中。这项研究将使用放射性碳同位素的测量来问一个问题：构成土壤有机质库的大部分的老碳是否因冻土融化而释放？实地测量将集中在阿拉斯加的一个地点，那里的永久冻土在过去几十年里一直在变暖和融化。这一领域在解决与北极生态系统变化相关的时间尺度上的问题方面是独一无二的。这一项目对全球碳循环的变化具有广泛意义。由于该碳库的体积大且具有潜在的反应性，储存在涝渍和冻土中的碳现在转移到大气中可能会对气候变化产生显着的正反馈。除了测量计划外，该项目还将支持一位经验丰富的记者每年作为该项目的顾问在实地工作。她将与科学家交流，并通过为各种公共广播和印刷媒体制作故事来传达研究结果。这些故事将与广泛的非专业观众分享这个项目的研究问题和影响。

ABSTRACTUp to 450 billion tons of soil carbon has accumulated in high latitude ecosystems after theretreat of the last major ice sheets. Recent studies suggest that these ecosystems may no longerbe accumulating carbon in soils, and in some cases may be losing stored carbon to theatmosphere. This study will use measurements of radiocarbon isotopes to ask the question: Is oldcarbon that comprises the bulk of the soil organic matter pool released in response to thawing ofpermafrost? Field measurements will center on a site in Alaska where permafrost has beenobserved to warm and melt over the past several decades. This area is unique for addressingquestions at the time scales relevant for change in arctic ecosystems.This project has broad significance for changes in the global carbon cycle. Transfer of carbonnow stored in waterlogged and frozen soils to the atmosphere could cause a significant positivefeedback to climate change due to the large size and potential reactivity of this carbon reservoir.In addition to the measurement program, this project will support an experienced journalist tospend time in the field each year as a consultant to the project. She will interface with scientistsand communicate the results of the research by producing stories for various public radio andprint outlets. These stories will share the research questions and implications of this project witha broad-based, lay audience.