Collaborative Research: Understanding the Distribution and Stable-Isotopic Composition of Planktonic Foraminifera in the Western Arctic Ocean

缺乏对北冰洋西部浮游有孔虫分布及其稳定同位素组成的了解，是我们恢复其古气候历史能力的一个重大缺陷。这项建议旨在深入调查北冰洋楚科奇/阿拉斯加地区水柱和海底表层沉积物中的浮游有孔虫和稳定同位素。该区域的特点是受北极和太平洋水域相互作用和冰缘过程影响的动态水文系统。需要了解这一系统的演变是因为现代冰盖急剧减少，影响到该区域内外海洋和沿海环境的许多方面。浮游有孔虫将在特定深度的浮游生物拖带中进行调查。调查将包括：(1)从63米开始的几个大小部分的活有孔虫和空测试的鉴定和计数，(2)从各自的亚样测量有孔虫方解石中碳和氧的稳定同位素，以及(3)环境水中的稳定同位素测量。NSF陆架-盆地相互作用计划2002-2004年收集的海底表层沉积物样品中浮游有孔虫及其稳定同位素组成的类似调查将补充这项研究。履行机构收集和/或汇编的大量水文、水化学、生物和冰数据将有助于对结果的解释。这项研究的结果将使浮游有孔虫及其稳定的同位素特征能够用作反映北冰洋西部水文和冰情的古海洋学指标。这项研究的具体目标将侧重于了解水文和水化学对水柱中有孔虫和稳定同位素分布的控制以及楚科奇/阿拉斯加地区海底沉积物中各自的空间模式。除了这些结果对北极西部古气候研究的重要性外，它们还将提高我们对低温海洋环境中生物介导的钙化过程的基础知识。这项研究的社会意义源于需要全面评估现代气候变化对楚科奇/阿拉斯加地区的潜在影响，该地区有许多社会经济方面的问题。该项目的工作将涉及两所大学的研究生和几名本科生的培训。

The deficiency of knowledge on the distribution of planktonic foraminifers and their stable-isotopic compositions in the western Arctic Ocean constitutes a significant shortcoming in our capabilities to reconstruct its paleoclimatic history. This proposal aims at an in-depth investigation of planktonic foraminifers and stable isotopes in the water column and seafloor surface sediments in the Chukchi/Alaskan region of the Arctic Ocean. This area is characterized by a dynamic hydrographic system affected by the interaction of Arctic and Pacific waters and ice marginal processes. The need for understanding the evolution of this system is caused by dramatic modern reduction in ice cover that affects many aspects of marine and coastal environments in and far beyond the region. Planktonic foraminifers will be investigated in depth-specific plankton tow. The investigation will include (1) identification and counts of live foraminifers and empty tests in several size fractions starting at 63 m, (2) measurements of stable isotopes of carbon and oxygen in foraminiferal calcite from respective subsamples, and (3) stable-isotopic measurements in ambient water. This study will be supplemented by the similar investigation of planktonic foraminifers and their stable-isotopic compositions in seafloor surface sediment samples collected by the NSF Shelf-Basin Interaction (SBI) Program in 2002-2004. Interpretation of results will be facilitated by the extensive hydrographic, hydrochemical, biological, and ice data collected and/or compiled by the SBI. Results of this study will enable the use of planktonic foraminifers and their stableisotopic signatures as paleoceanographic proxies for hydrographic and ice conditions in the western Arctic Ocean. Specific objectives of this research will focus on understanding hydrographic and hydrochemical controls on the distribution of foraminifers and stable isotopes in the water column as well as respective spatial patterns in seafloor sediments across the Chukchi/Alaskan region. In addition to the importance of these results for paleoclimatic research in the western Arctic, they will also improve our fundamental knowledge of biologically-mediated calcification processes in low-temperature marine environments. The societal significance of this research stems from the need for a comprehensive evaluation of the potential effects of modern climatic change on the Chukchi/Alaskan region that has many socio-economical aspects. Work on the project will involve training of graduate and several undergraduate students in two universities.