EAGER: Quantification of Dissolved Titanium in Open Ocean Seawater

针对颗粒通量的无机和有机代理研究的一个重要方面是追踪铝硅酸盐输入，以限制大气灰尘和河流物质的来源，这两者对于了解地球化学循环和气候在空间和时间上的变化至关重要。 量化颗粒和沉积物中的碎屑物质对于确定灰尘和河流通量至关重要，以便解释成分稀释（即，归一化为100%，作为封闭阵列），其影响测量的组成。 为了从总通量中“去除”陆源成分，计算无机铝硅酸盐物质至关重要。 沿着铝和同位素Th 232，元素钛（Ti）通常用于这些目的，但需要更仔细地考虑这些物质真正仅包含在耐火铝硅酸盐相中的假设。 公开发表的钛在大洋中的分布图不到五个，需要更大的覆盖面来充分了解这一重要元素的复杂地球化学。 如果没有这样的理解，钛作为示踪剂的使用将不会发挥其最大的潜力。 20世纪90年代初的开创性工作为基于树脂的预浓缩程序奠定了基础，随后通过ICP-MS分析进行定量。 通过EAGER奖的资助，波士顿大学的研究人员将（a）开发一种方法来量化公海海水中溶解的钛，以及（B）将这种方法应用于一套先前收集的样本，以测试GEOTRACES玫瑰花形采样系统（其中一小部分由含钛材料制成）是否可用于收集未受钛污染的海水样本。 新分析方法基于新树脂NOBIAS CHELATE-PA 1。 这种基于EDTA的树脂是专门为GEOTRACES研究量身定制的，并已被证明可以对一系列其他低浓度元素进行出色的预浓缩，然后进行ICP-MS分析。 这项研究将是第一个只关注Ti的研究。 在与GSO-URI、麻省理工学院和加州大学圣克鲁斯的合作者协商后，波士顿大学团队制定了一项分析研究计划，包括研究沿海海水样本、标准参考物质、校准样本（例如，SAFe）、采用已建立的清洁取样技术采集的非GEOTRACES样品和GEOTRACES材料。 该策略将使团队能够实现建立新技术和测试GEOTRACES玫瑰花结对Ti的适用性的双重目标。 更广泛的影响：拟议的研究预计将产生几个重大的更广泛的影响。 首先，这项研究对社会有明显的好处，因为最终了解Ti的地球化学循环的能力将显着提高我们追踪灰尘和河流通量的能力-这两者都将有助于在多个时空尺度上研究气候变化。 该项目还将通过在多个机构（波士顿大学、罗得岛大学、马萨诸塞州理工学院、加州大学圣克鲁斯分校）之间建立合作，加强研究和教育基础设施。 该提案还涉及下一代仪器和分析方法的开发。 最后，首席研究员长期以来一直将其研究成果纳入本科和研究生一级的学习和教育，本项目非常适合继续开展此类活动。

An important aspect of studies targeting inorganic and organic proxies of particle flux to the open ocean has been to trace aluminosilicate inputs to constrain sources of atmospheric dust and fluvial material, both of which are critical for understanding biogeochemical cycling and climate variability in space and time. Quantifying detrital material in particles and sediments is essential to determine dust and fluvial fluxes, so as to account for compositional dilution (i.e., normalization to 100% as a closed array) that affects measured composition. Accounting for the inorganic aluminosilicate material is vital in order to "remove" the terrigenous component from the total flux. Along with the aluminum and the isotope Th232, the element titanium (Ti) is commonly used towards these ends, but the assumption that these species are truly only contained in the refractory aluminosilicate phase(s) needs to be considered more carefully. There are less than five published profiles of Ti in the open ocean, and greater coverage is needed to fully understand the complex biogeochemistry of this important element. Without such an understanding, the use of Ti as a tracer will not be to its fullest potential. Pioneering work in the early 1990s laid the groundwork for a resin-based pre-concentration procedure followed by quantification by ICP-MS analysis. With funding through this EAGER award, researchers at Boston University will (a) develop a methodology to quantify dissolved Ti in open ocean seawater, and (b) apply this methodology to a suite of previously gathered samples to test whether the GEOTRACES rosette sampling system, small parts of which are constructed of Ti-bearing materials, can be used to gather seawater samples that are uncontaminated with respect to Ti. The new analytical procedure is based on a new resin, NOBIAS CHELATE-PA1. This EDTA-based resin is tailored specifically for GEOTRACES research, and has been shown to result in excellent pre-concentration, followed by ICP-MS analysis, for a suite of other low-concentration elements. This study will be the first to solely focus on Ti. In consultation with collaborators at GSO-URI, MIT, and UC Santa Cruz, the Boston University team have developed an analytical research plan comprising the study of coastal seawater samples, Standard Reference Materials, calibration samples (e.g., SAFe), non-GEOTRACES samples gathered with established clean sampling techniques, and GEOTRACES materials. This strategy will allow the team to achieve the dual goals of establishing the new technique and testing the suitability of the GEOTRACES rosette for Ti. Broader Impacts: The proposed research is expected to have several significant Broader Impacts. First, the research has clear benefit to society in that the ability to eventually understand the geochemical cycling of Ti will significantly improve our ability to trace dust and fluvial fluxes -- both of which will assist in the study of climate change over multiple temporal and spatial scales. The project also will enhance infrastructure for research and education, by establishing collaborations between multiple institutions (Boston University, University of Rhode Island, Massachusetts Institute of Technology, UC-Santa Cruz). This proposal also speaks to the development of next-generation instrumentation and analytical methodologies. Finally, the lead investigator has a long record of incorporating his research results into learning and education at the undergraduate and graduate level, and this project is well-suited to continuing such activities.