Doctoral Dissertation Research: The impact of permafrost thaw on the fate and magnitude of carbon aquatic transport from Arctic tundra soil

北极流域的永久冻土融化引发了以前被隔离的古老碳释放到大气和河流系统中-这是加速气候变暖的反馈。几十年来，碳在大气中的释放已经得到了很好的记录;然而，水更难以监测，它在北极碳循环中的作用往往被忽视。这项研究将探索北极地下水和源头河流在长期冻土碳释放中发挥的环境驱动力。更好地了解水在北极变暖的碳循环中发挥的新作用将有助于改善区域碳预算，量化通过永久冻土下的流域河流输出的土地碳损失量。这项研究还将有助于监测气候变化和由此产生的永久冻土融化对古代永久冻土碳释放的影响，方法是对河流中溶解的碳进行碳定年，以确定古代永久冻土的特征。 在阿拉斯加内陆的一个长期实验研究地点，每年有50%的土壤碳损失在大气碳通量测量中无法解释。据推测，丢失的50%的碳损失将以溶解有机碳通量的形式输出，并且随着冻土融化的增加，每年都会释放出越来越多的古冻土碳。这项研究将（1）有助于解决北极净生态系统碳收支，并有助于参数化未来的地球系统模型;（2）确定溶解的有机碳的比例是古代永久冻土碳，使用放射性碳测年;以及（3）确定环境驱动因素，如解冻，影响溶解有机碳浓度和年龄，以帮助限制溶解有机碳输出的未来预测。此外，该项目团队将促进在亚利桑那州和阿拉斯加内陆现场周围的当地社区内开展各种外展活动，以包括更广泛的公众以及未来的年轻科学家队伍。该奖项反映了NSF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。

Permafrost thaw in Arctic watersheds triggers the release of previously sequestered, ancient carbon to the atmosphere and to stream systems - a feedback that accelerates climate warming. Atmospheric release of carbon has been well-documented for decades; however, water is more difficult to monitor and its role in the Arctic carbon cycle has often been overlooked. This research will explore the environmental drivers that Arctic groundwater and headwater streams play in long-term permafrost carbon release. Better understanding the emerging role that water plays in the carbon cycle in a warming Arctic will help improve regional carbon budgets, quantifying the amount of carbon lost from the land that is exported via rivers in a watershed underlain by permafrost. The research will also aid in monitoring the impacts that climate change and resulting permafrost thaw have on ancient permafrost carbon release by carbon dating the dissolved carbon carried away in rivers to identify ancient permafrost signatures. At a long-term experimental study site in interior Alaska, 50% of the soil carbon lost from soils annually was unaccounted for in atmospheric carbon flux measurements. The missing 50% of carbon lost is hypothesized to be exported in dissolved organic carbon fluxes and that an increasing amount of ancient, permafrost carbon is released each year with increasing permafrost thaw. This research will (1) help to resolve the Arctic net ecosystem carbon budget and help to parameterize future Earth System Models; (2) identify the proportion of dissolved organic carbon that is ancient permafrost carbon, using radiocarbon dating; and (3) identify how environmental drivers, such as thaw, impact dissolved organic carbon concentration and age in order to help constrain future predictions of dissolved organic carbon export. Further, the project team will facilitate various outreach activities in Arizona and within the local community surrounding the field site in interior Alaska, to include the broader public as well as a future cohort of young scientists in this work.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.