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

摘要：主要营养物质硝酸盐和磷酸盐的高浓度是南大洋南极区的基本特征，对其在全球海洋肥力和全球碳循环中的作用至关重要。硅藻结合的有机氮的同位素组成是重建极地地表水在冰期循环中的营养状况的最大希望之一，这反过来可能解释冰期大气中二氧化碳的减少。PIs建议从克格伦高原的高沉积速率岩心中生成详细的硅藻结合氮同位素（δ15Ndb）记录。由于这些岩心是在相对较浅的海底深处收集的，因此它们有足够的浮游生物和底栖有孔虫来建立准确的年龄模型。得到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，包括进入和退出冰期的主要步骤，以及冰期期间和结束时发生的千年尺度的事件。在这个项目中产生的记录将为冰期二氧化碳减少的原因提供一个关键的假设测试。更广泛的影响：这项研究将有助于了解冰河期和过去的二氧化碳变化，这两者对未来的气候都有广泛的影响。本科生将进行暑期实习，有可能将他们的工作扩展到大三的项目和大四的论文。此外，PI将为普林斯顿大学的两个中学教师项目领导模块，并将主持一名教师进行为期六周的暑期研究项目。

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.