Coupling of Silicon Isotope Distributions to Meridional Overturning Circulation of the North Atlantic

硅(Si)同位素替代物越来越多地被用来评估硅藻和硅酸在过去海洋生产力变化中的作用及其对气候的影响；然而，在成功使用它之前，我们需要了解控制通风水团中硅同位素组成的空间和时间变异性的机制。加州大学圣巴巴拉分校的一位科学家提出了一个假设，即硅同位素分布是硅石生产过程中和硅石溶解过程中分馏与生物泵和子午线翻转环流(MOC)耦合的函数。为了验证这一假设，研究人员计划测量北大西洋主要水团中的硅同位素，北大西洋是MOC中的一个关键终端成员(即地表水和模式水，向南流动的北大西洋深水，以及向北流动的对应水：南极中水和南极底层水)。此外，由于硅同位素工作的样品是作为2011年GEOTRACES北大西洋地带区的一部分收集的，这位科学家有机会与氮(N)同位素研究人员合作，确定氮和硅同位素动态的控制，并创建第一个包括这两种同位素的数值模型，以及在二氧化硅溶解过程中纳入硅同位素分馏。就更广泛的影响而言，所产生的数据将提交给地球观测卫星系统数据库，从而随时可供科学界使用。作为该项目的一部分，两名本科生将得到支持和培训。

The silicon (Si) isotope proxy is increasingly being used to assess the role of diatoms and silicic acid in past shifts in ocean productivity and their implication for climate; however, before it can be successfully used, we need to understand the mechanisms that control the spatial and temporal variability of the Si isotope composition in ventilating water masses. A scientist from the University of California, Santa Barbara put forth the hypothesis that the Si isotope distribution is a function of the coupling of fractionation during silica production and during silica dissolution to the biological pump and the meridional overturning circulation (MOC). To test the hypothesis, the researcher plans to measure Si isotopes within the major water masses of the North Atlantic, a key end member within the MOC (i.e., surface and mode waters, the southward flowing North Atlantic Deep Water, and its northward flowing counterparts: Antarctic Intermediate Water and Antarctic Bottom Water). In addition, because the samples for the Si isotope work are being collected as part of the 2011 GEOTRACES North Atlantic zonal section, the scientist has the opportunity to collaborate with researchers working on nitrogen (N) isotopes to determine the controls on N and Si isotope dynamics and create the first numerical model that includes both isotopes, as well as incorporates Si isotope fractionation during silica dissolution. In terms of the broader impacts, data generated will be submitted to the GEOTRACES databases and thereby be readily available to the science community. Two undergraduate students will be supported and trained as part of this project.