Reconstructing Glacial Nitrogen and Carbon Cycling Using Isotopes

对深海沉积物中氮和碳同位素的测量证明，在上一个冰河时代和现代海洋之间发生了巨大的变化。然而，氮和碳同位素都受到不同的物理和生物地球化学过程的影响，这使得它们的解释不明确。在这项研究中，一个基于过程的气候、海洋环流和生物地球化学耦合模型，其中包括碳和氮同位素，将与沉积物数据结合使用，以重建冰川氮和碳循环。该模型将进行修订，明确的铁循环和全球数据库的氮和碳同位素从最后一次冰盛期和现代海洋沉积物将被汇编。这一方法可以检验关于海洋氮总库存的变化、由于施铁肥引起的极地养分消耗及其对大气二氧化碳浓度的影响的假设。该项目继续了俄勒冈州立大学一名气候建模人员和一名古海洋学家之间的合作，以及与麦吉尔大学一名加拿大研究人员的国际合作。资金支持一名研究生，为来自俄勒冈州各地的30名K-12教师举办暑期研讨会，以及为俄勒冈州立大学的本科生提供暑期研究体验。此外，研究人员将积极参与古气候模拟对比项目(PMIP)和新的古碳模拟对比项目(PCMIP)，这两个项目旨在评估古气候条件下气候模型的技能并提高对过去气候变化的理解。

Measurements of nitrogen and carbon isotopes from deep-sea sediments document dramatic changes between the last ice age and the modern ocean. However, both nitrogen and carbon isotopes are influenced by different physical and biogeochemical processes, which makes their interpretation ambiguous. In this research, a process-based coupled model of climate, ocean circulation and biogeochemistry that includes carbon and nitrogen isotopes will be used in conjunction with sediment data in order to reconstruct glacial nitrogen and carbon cycles. The model will be amended with explicit iron cycling and global databases of nitrogen and carbon isotopes from Last Glacial Maximum and modern ocean sediments will be compiled. This approach allows testing of hypotheses concerning changes in the total ocean nitrogen inventory, polar nutrient consumption due to iron fertilization and their effects on atmospheric CO2 concentrations. The project continues collaboration between a climate modeler and a paleoceanographer from Oregon State University and international collaboration with a Canadian investigator from McGill University. Funding supports a graduate student, a summer workshop for 30 K-12 teachers from all parts of Oregon and a summer research experience for an undergraduate student at Oregon State University. In addition, the researchers will actively participate in both the Paleoclimate Modeling Intercomparison Project (PMIP) and in the new Paleo Carbon Modeling Intercomparison Project (PCMIP), efforts that evaluate the skill of climate models under paleoclimate conditions and improve understanding of past climate changes.