Developing a New Paleosalinity Proxy Based on Na/Ca Ratios in the Planktonic Foraminifera Trilobatus sacculifer and Globigerinoides ruber

本项目将开发一种估算过去海洋表面盐度的新方法。盐度被用来了解气候变化时的海洋和大气状况。它还使科学家能够预测未来气候将如何变化。在大西洋进行的初步研究表明，随着盐度的增加，浮游生物的小壳中的钠含量也会增加。该项目将扩大研究范围，包括大西洋、太平洋和印度洋。为了提高校准的准确性，该项目还将研究贝壳沉入海底时部分溶解的钠是如何流失的。改进后的测量方法将在跨越最后一个冰河时代的长沉积物岩心上进行测试。该项目将支持本科生和研究生的教育和专业发展。该项目还将制作专业质量的YouTube视频，旨在教育公众了解重要的气候变化问题。本项目将从横跨亚热带/热带大西洋、太平洋和印度洋的一套沉积物岩心顶部，基于三叶虫和gloigerinoides橡胶这两种浮游有孔虫的Na/Ca比值，开发一种新的上层海洋古盐度代用物。根据9个大西洋岩心顶部的初步结果，盐度是控制T. sacacculifer壳Na/Ca比值的主要因素。然而，最初的校准需要扩展到更大的盐度范围和其他海洋盆地。由于在所有地点的区系组合中并不总是丰富的，因此本项目还将开发一种用于重建海表温度（SST）和盐度研究的g.r uber的校准，g.r uber是一种比ssugler栖息地更浅的物种。因此，该项目的主要目标是开发可在任何地点使用的特定物种的全球校准。该项目还将调查和量化溶解对大西洋和印度洋贝壳Na/Ca比率的影响，因为最近发表的一项研究表明，溶解显著影响热带太平洋的贝壳Na/Ca比率。这将通过测量来自热带大西洋和南印度洋的下坡岩心顶部来实现。最后，新开发的校准将用于生成海洋同位素阶段3期间墨西哥湾流中Na/Ca-based盐度变化的高分辨率记录，并将其与先前发表的基于Mg/Ca-SST结合G. ruber中的<s:1> 18O值计算的海水盐度记录进行比较。该项目将支持本科生和研究生的教育和专业发展。该项目还将制作专业质量的YouTube视频，旨在教育公众了解重要的气候变化问题。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will develop a new method of estimating past ocean surface salinity. Salinity is used to understand ocean and atmospheric conditions as climate changes. It also allows scientists to predict how the climate will change in the future. Preliminary studies in the Atlantic Ocean show that sodium increases in the tiny shells of plankton as the salinity increases. This project will expand the range of study to include the Atlantic, Pacific, and Indian Oceans. To improve the accuracy of the calibration, this project will also study how the shells lose sodium as they partially dissolved when sinking to bottom of the ocean. The improved measurement will be tested on long sediment cores than span the last ice age. This project will support the educational and professional development of undergraduate and graduate students. The project will also produce professional quality YouTube videos aimed at educating the public on important climate change issues.This project will develop a new upper ocean paleosalinity proxy based on Na/Ca ratios in two species of planktic foraminifera, Trilobatus sacculifer and Globigerinoides ruber, from a suite of sediment core tops spanning the subtropical/tropical Atlantic, Pacific, and Indian Oceans. Based on initial results from nine Atlantic core tops, salinity is the dominant factor controlling shell Na/Ca ratios in T. sacculifer. However, the initial calibration needs to be expanded across a wider range of salinities and in other ocean basins. Because T. sacculifer is not always abundant in faunal assemblage at all locations, this project will also develop a calibration for G. ruber, a species with an even shallower depth habitat than T. sacculifer that is commonly utilized in studies reconstructing sea surface temperature (SST) and salinity. The major goal of this project, therefore, is to develop species-specific global calibrations that can be used at any location. This project will also investigate and quantify the effects of dissolution on shell Na/Ca ratios in the Atlantic and Indian Oceans, as a recently published study showed that dissolution significantly impacts shell Na/Ca ratios in the tropical Pacific. This will be achieved by measuring down-slope core tops from the tropical Atlantic and the south Indian Ocean. Finally, the newly developed calibrations will be used to generate a high-resolution record of Na/Ca-based salinity change in the Gulf Stream during Marine Isotope Stage 3 and compare it to a previously published salinity record based on the calculation of 18Oseawater using Mg/Ca-SST combined with 18O values in G. ruber. This project will support the educational and professional development of undergraduate and graduate students. The project will also produce professional quality YouTube videos aimed at educating the public on important climate change issues.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.