Lead and Lead Isotope Sample Collection and Analysis for the U.S. GEOTRACES Zonal North Atlantic Survey Section

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际GEOTRACES计划的目的是建立一个关键微量元素和同位素的全球框架，以描述这些属性在海洋中的当代分布。然后，这些信息可用于约束生物地球化学重要元素的过程和通量模型，以及构成通量过程和转换的关键示踪剂。麻省理工学院的一名科学家将在2010年GEOTRACES北大西洋巡航期间收集样本，并分析其中的铅（Pb）和铅同位素。将从显示影响微量金属及其同位素的物理和生物地球化学过程的地点采集样本（即强经向平流、边界清除和来源、风成沉积、从地中海和拉布拉多海输入的中间水以及人为影响的证据）。科学家将通过生成的数据集解决以下问题：(1)自1999年以来在副热带大西洋西部和东部的海洋中演变的Pb和Pb同位素剖面；(2)它们的分布是与平流输运一致还是与下沉颗粒交换一致；(3)热液喷口的Pb或Pb同位素信号是否向源外传输了较远的距离；(4)北大西洋深水上下游的Pb和Pb同位素组成有何差异，这些差异在西边界上的横向表现如何？此外，由于Pb与其他微量金属在大气沉降、生物吸收和非生物清除方面的行为相似，因此本研究的结果将适用于其他元素。至于更广泛的影响，这项工作将有助于建立更准确的生物地球化学模型，使科学家能够了解未来气候变化和人为污染的影响。作为该项目的一部分，将培训和支持一名研究生。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The international GEOTRACES program has been developed to produce a global framework of key trace elements and isotopes that will describe the contemporary distributions of these properties in the ocean. This information can then be used to constrain models of the processes and fluxes of biogeochemically important elements and key tracers that frame flux processes and transformations. A scientist from Massachusetts Institute of Technology will collect samples during the GEOTRACES North Atlantic cruise in 2010 and analyze them for lead (Pb) and Pb isotopes. Samples will be taken from sites that exhibit the physical and biogeochemical processes that influence trace metals and their isotopes (i.e., strong meridional advection, boundary scavenging and sources, aeolian deposition, input of intermediate waters from the Mediterranean and Labrador Seas, and evidence of anthropogenic impacts). Amongst the questions the scientist will address with the dataset to be generated are the following: (1) have profiles of Pb and Pb isotopes in the ocean evolved in the western and eastern subtropical Atlantic since 1999; (2) is their distribution consistent with advective transport or with exchange on sinking particle; (3) are Pb or Pb isotope signals from hydrothermal vents transported a significant distance beyond the source?; and (4) how do upper and lower North Atlantic Deep Water differ in their Pb and Pb isotopic composition, and how are these differences expressed laterally over the western boundary? In addition, because Pb behaves similarly to other trace metals as regards atmospheric deposition, biological uptake, and abiotic scavenging, results from this study will be applicable to other elements. As regards broader impacts, this work will aid in creating more accurate biogeochemical models allowing scientists to access the impact of future climate change and anthropogenic pollution. One graduate student would be trained and supported as part of this project.