Collaborative Research: GEOTRACES - Application of 210-Pb and 210-Po distribution at North Atlantic interface regimes

合作研究：GEOTRACES - 210-Pb 和 210-Po 分布在北大西洋界面区域的应用

• 批准号: 0961653
• 负责人: Thomas Church
• 金额: $ 14.02万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961653&HistoricalAwards=false
• 关键词: Collaborative; Research; GEOTRACES; Application; 210

Trace elements and isotopes (TEIs) in the natural U-Th radionuclide series are central to the goals of the U.S. GEOTRACES during its funded North Atlantic phase over the next three years. The radionuclide 210Po-210Pb pair is designated as one of the priority TEIs by the U.S. GEOTRACES Zonal North Atlantic Survey Section Implementation Plan. The pair has seen application since GEOSECS for quantifying particulate scavenging and carbon flux within the ocean, but processes are still poorly understood at oceanic interfaces. The atmospheric source and half lives of the two isotopes (138 d and 22.3 y) present time frames uniquely suited to trace interface (air-water, bio-water, and sediment-water) processes in the North Atlantic sections. Under this award, researchers at the University of Delaware, Wayne State University, and Queens College will participate in the U.S.GEOTRACES North Atlantic campaign to study the relationships between these two radioisotopes and the other trace elements and isotopic tracers that will be surveyed. Their work will center around a set of hypotheses. At the air-sea interface, they hypothesize that as the primary input of 210Pb into the surface ocean, levels will be source dependent on the continental input mixtures, in the western temperate and easterly sub-tropical sections. At the biotic-water interface, they hypothesize that different biogenic particle types encountered in the upper waters will affect the fractionation and remineralization depths of 210Po and 210Pb. At the particle-water interface, they hypothesize that interfaces between intermediate lithogenic nepheloid layers (INL) or hydrothermal plumes will be zones of enhanced 210Po and 210Pb scavenging from the surrounding waters. To test these hypotheses, they will sample and analyze several hundred dissolved and particulate (large and small) samples for 210Po and 210Pb along the GEOTRACES North Atlantic section. About two thirds of the samples will be focused at the six designated "super stations", half above the main thermocline and the other half down across the BNL. The depths will be chosen according to regional atmospheric input, ecosystems, and coordinated TEI sampling. The other third will be detailed across INL detached plumes from coastal waters, across the BNL, and within hydrothermal plumes. The data will be synthesized according to interface scavenging models by particle types (e.g. fine/colloidal, lithogenic and biogenic). As such, the proposed work will be closely coordinated with GEOTRACES PIs already funded to for other particle-reactive (e.g. Th, Pa) or dissolved (e.g. Ra) radionuclide isotopes in the Atlantic Survey Section of GEOTRACES. Broader Impacts: The broader impacts are closely linked to the GEOTRACES Program as a whole to enhance (1) research infrastructure by providing a broad array of 210Po and 210Pb data useful for biogeochemical scavenging models, (2) education by mentoring graduate and undergraduates, teaching by example from proposed research, (3) participation of under-represented students careers in the geosciences, (4) research training of graduates in marine radiochemistry, and 5) broad dissemination of results through publications, presentations, and on dedicated public UD websites (www.ocean.udel.edu) and at GEOTRACES (www.geotraces.org).

天然 U-Th 放射性核素系列中的微量元素和同位素 (TEI) 是美国 GEOTRACES 在未来三年资助的北大西洋阶段目标的核心。放射性核素 210Po-210Pb 对被美国 GEOTRACES 分区北大西洋调查部分实施计划指定为优先 TEI 之一。自 GEOSECS 以来，这对数据已被应用于量化海洋内的颗粒物清除和碳通量，但人们对海洋界面的过程仍然知之甚少。两种同位素（138 d 和 22.3 y）的大气源和半衰期呈现出特别适合北大西洋部分的痕量界面（空气-水、生物水和沉积物-水）过程的时间框架。根据该奖项，特拉华大学、韦恩州立大学和皇后学院的研究人员将参加美国 GEOTRACES 北大西洋活动，研究这两种放射性同位素与将要调查的其他微量元素和同位素示踪剂之间的关系。 他们的工作将围绕一组假设展开。在海气界面，他们假设，作为 210Pb 进入表层海洋的主要输入，在西温带和东亚热带地区，其水平将取决于大陆输入混合物的来源。在生物-水界面，他们假设在上层水域遇到的不同生物颗粒类型将影响 210Po 和 210Pb 的分馏和再矿化深度。 在颗粒-水界面处，他们假设中间成岩霞云层 (INL) 或热液羽流之间的界面将是周围水域 210Po 和 210Pb 清除增强的区域。为了测试这些假设，他们将沿 GEOTRACES 北大西洋部分采样并分析数百个溶解和颗粒（大和小）样品的 210Po 和 210Pb。大约三分之二的样本将集中在六个指定的“超级站”，一半位于主温跃层上方，另一半位于 BNL 下方。深度将根据区域大气输入、生态系统和协调的 TEI 采样来选择。另外三分之一将详细介绍 INL 沿海水域的分离羽流、BNL 的羽流以及热液羽流内的羽流。数据将根据颗粒类型（例如细粒/胶体、成岩和生物）的界面清除模型进行合成。因此，拟议的工作将与已资助 GEOTRACES 大西洋调查部分其他粒子反应性（例如 Th、Pa）或溶解（例如 Ra）放射性核素同位素的 GEOTRACES PI 密切协调。更广泛的影响：更广泛的影响与整个 GEOTRACES 计划密切相关，旨在加强 (1) 通过提供对生物地球化学清除模型有用的广泛 210Po 和 210Pb 数据来加强研究基础设施，(2) 通过指导研究生和本科生进行教育、教学以拟议研究为例，(3) 代表性不足的学生参与地球科学职业生涯，(4) 海洋放射化学毕业生的研究培训，以及 5) 广泛传播通过出版物、演示文稿以及专用公共 UD 网站 (www.ocean.udel.edu) 和 GEOTRACES (www.geotraces.org) 公布结果。