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

硅（Si）同位素代用品越来越多地被用来评估硅藻和硅藻酸在过去的海洋生产力的变化及其对气候的影响的作用，但是，在它可以成功地使用之前，我们需要了解的机制，控制的空间和时间变化的Si同位素组成通风水团。 加州大学圣巴巴拉分校的一位科学家提出了一个假设，即硅同位素分布是二氧化硅生产和二氧化硅溶解过程中分馏与生物泵和日冕翻转循环（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，这是MOC中的一个关键末端成员（即，表层水和模式沃茨、向南流动的北大西洋深层水及其向北流动的对应物：南极中层水和南极底层水）。 此外，由于硅同位素工作的样品是作为2011年GEOTRACES北大西洋带状部分的一部分收集的，科学家有机会与研究氮（N）同位素的研究人员合作，以确定对N和Si同位素动力学的控制，并创建第一个包括两种同位素的数值模型，以及在二氧化硅溶解期间纳入Si同位素分馏。就更广泛的影响而言，所产生的数据将提交给GEOTRACES数据库，从而可随时供科学界使用。 作为该项目的一部分，将支持和培训两名本科生。

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.