High-resolution, Assemblage-specific Records of Diatom-bound N Isotopes from the Indian Sector of the Antarctic Ocean

摘要：高浓度的主要营养盐硝酸盐和磷酸盐是南大洋南极区的一个基本特征，是其在全球海洋肥力和全球碳循环中的核心作用。结合有机氮的同位素组成是重建极地表面沃茨在冰期循环中营养状态的最佳希望之一，这反过来又可能解释冰期期间大气二氧化碳的下降。PI建议从Kerguelen高原的高沉积速率岩心中生成详细的氮同位素（#948; 15 Ndb）记录。由于岩芯是在相对较浅的海底深度采集的，因此有足够的浮游有孔虫和底栖有孔虫，可以建立准确的年龄模型。由此产生的数据可以与南极冰芯和其他档案的气候记录进行比较，以调查与气候有关的变化，包括进入和退出冰河时代的主要步骤以及冰河时代期间和结束时发生的千年规模的事件。在这个项目中产生的记录将提供一个关键的测试假设的原因较低的冰河时期二氧化碳。更广泛的影响：这项研究将有助于了解冰河时代和过去的二氧化碳变化，这两者都对未来的气候有广泛的影响。本科生将进行暑期实习，并有可能将他们的工作扩展到大三的项目和高级论文。此外，PI将领导两个普林斯顿计划的中学教师模块，并将主办为期六周的夏季研究项目的教师。

ABSTRACTIntellectual Merit:The high concentration of the major nutrients nitrate and phosphate is a fundamental characteristic of the Antarctic Zone in the Southern Ocean and is central to its role in global ocean fertility and the global carbon cycle. The isotopic composition of diatom-bound organic nitrogen is one of the best hopes for reconstructing the nutrient status of polar surface waters over glacial cycles, which in turn may hold the explanation for the decline in atmospheric carbon dioxide during ice ages. The PIs propose to generate detailed diatom-bound nitrogen isotope (δ15Ndb) records from high sedimentation rate cores from the Kerguelen Plateau. Because the cores were collected at relatively shallow seafloor depths, they have adequate planktonic and benthic foraminifera to develop accurate age models. The resulting data could be compared with climate records from Antarctic ice cores and other archives to investigate climate-related changes, including the major steps into and out of ice ages and the millennial-scale events that occur during ice ages and at their ends. The records generated in this project will provide a critical test of hypotheses for the cause of lower ice age CO2. Broader impacts:This study will contribute to the goal of understanding ice ages and past CO2 changes, which both have broad implications for future climate. Undergraduates will undertake summer internships, with the possibility of extending their work into junior year projects and senior theses. In addition, the PI will lead modules for two Princeton programs for middle school teachers and will host a teacher for a six-week summer research project.