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: 0961351
• 负责人: Mark Baskaran
• 金额: $ 9.99万
• 依托单位: Wayne State University
• 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 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961351&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（TEIs）是美国GEOTRACES在其资助的北大西洋阶段未来三年目标的核心。放射性核素210Po-210Pb对被美国GEOTRACES北大西洋分区调查部门实施计划指定为优先tei之一。自GEOSECS以来，这两种方法已经被用于量化海洋中的颗粒清除和碳通量，但对海洋界面的过程仍然知之甚少。这两种同位素（138 d和22.3 y）的大气源和半衰期提供的时间框架特别适合于北大西洋剖面的痕量界面（空气-水、生物水和沉积物-水）过程。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被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系列假设展开。在海气界面，他们假设210Pb作为海洋表面的主要输入源，在西温带和偏东副热带地区，其水平将取决于大陆输入的混合来源。在生物-水界面，他们假设上层水体中遇到的不同生物成因颗粒类型会影响210Po和210Pb的分选和再矿化深度。在颗粒-水界面，他们假设中间成岩星云层（INL）或热液柱之间的界面将是从周围水体中增强清除210Po和210Pb的区域。为了验证这些假设，他们将沿着GEOTRACES北大西洋剖面取样并分析数百个溶解和颗粒（大小）样品，以检测210Po和210Pb。大约三分之二的样本将集中在六个指定的“超级站”，一半在主温跃层上方，另一半在北纬界线下方。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从沿海水域分离的羽流，横跨BNL，以及热液羽流。数据将根据颗粒类型（如细/胶体、岩石成因和生物成因）的界面清除模型进行合成。因此，拟议的工作将与GEOTRACES的pi密切协调，这些pi已获得资助，用于GEOTRACES大西洋调查科的其他粒子反应性（如Th、Pa）或溶解性（如Ra）放射性核素同位素。更广泛的影响:更广泛的影响与GEOTRACES项目作为一个整体密切相关，以加强(1)研究基础设施，为生物地球化学清除模型提供广泛的210Po和210Pb数据，(2)通过指导研究生和本科生进行教育，从拟议的研究中进行实例教学，(3)参与代表性不足的学生在地球科学领域的职业生涯，(4)海洋放射化学毕业生的研究培训，5)通过出版物、演讲以及专门的公共大学网站（www.ocean.udel.edu）和GEOTRACES （www.geotraces.org）广泛传播研究结果。