Quantifying Upper Ocean Export and Remineralization of Bioactive and Particle Reactive Trace Elements along the US GEOTRACES Tahiti to Alaska Transect

量化美国 GEOTRACES 塔希提岛至阿拉斯加断面沿线生物活性和粒子反应性微量元素的上层海洋出口和再矿化

• 批准号: 1735445
• 负责人: Ken Buesseler
• 金额: $ 60.35万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1735445&HistoricalAwards=false
• 关键词: Quantifying; Upper; Ocean; Export; Remineralization

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. A core approach of GEOTRACES involves coordinated expeditions that measure multiple trace elements and isotopes (TEIs) across key gradients in the ocean, such as changes in productivity, redox/oxygen, boundary scavenging intensity, and hydrothermal activity. However, trace elemental distributions are not enough to meet the GEOTRACES goal to "identify processes and quantify fluxes that control the distribution of TEIs in the ocean and to establish the sensitivity of these changing distributions to environmental conditions." To measure rates of processes requires the use of other measurements, such as natural ly occurring radioactive isotopes. This project involves the measurement of two isotopes of the element thorium on a U.S. GEOTRACES expedition in the Pacific Ocean, from Alaska to Tahiti. Thorium has a tendency to become associated with particles in the oceans, and therefore it can be used to measure the sinking of other elements out of the ocean surface. Thorium isotopes with short half-lives can be used to track processes that occur on faster timescales (weeks or seasons), such as those related to biology in the surface waters of the ocean, while isotopes with longer half-lives are useful for studying processes that occur on longer time scales like that of ocean circulation. This project would use measurements of thorium-234 and thorium-228, with half-lives of 24.1 days and 1.9 years, respectively, to estimate sinking rates of thorium and other elements in the upper ocean.The proposal is broken down into four main activities: 1) Use short-lived Th-234 to estimate particle export and remineralization rates; 2) use ratios of Th-234 to major biogenic phases (e.g., carbon, nitrogen, biogenic silica) and trace elements (e.g. iron, manganese, etc.) to derive flux profiles of other major and trace elements; 3) extend the export and remineralization rates in time/depth using Th-228; 4) examine how changes in #1-3 are related to expected gradients in particle concentration and type, plankton community shifts, net community production, aerosol inputs/dust, physical forcing (e.g. upwelling), hydrothermal plumes, and other features along this GEOTRACES transect. Profiles of total Th-234:U-238 provide quantitative estimates of Th-234 flux vs. depth, which along with parallel size-fractionated particulate profiles of Th-234 and TEIs allow us to empirically calculate the vertical profile of net particle export for any TEI. With high resolution vertical and spatial sampling, the application of Th-234 can be extended below the zone of net removal in the surface ocean to include quantification of particle export and remineralization in the upper several hundred meters. Based upon prior studies, the Th-234 flux model will need to be adjusted for physical transport, especially upwelling across the equator. Selected Th-228 profiles can extend these flux and remineralization estimates even further with depth and over longer time scales. The project will support a Ph.D. student.

国际 GEOTRACES 计划的目标是了解海洋中微量化学元素及其同位素的分布。 GEOTRACES 的核心方法涉及协调探险，测量海洋关键梯度的多种痕量元素和同位素 (TEI)，例如生产力、氧化还原/氧气、边界清除强度和热液活动的变化。然而，痕量元素分布不足以满足 GEOTRACES 的目标，即“识别控制海洋中 TEI 分布的过程和量化通量，并确定这些变化的分布对环境条件的敏感性”。要测量过程速率需要使用其他测量方法，例如天然存在的放射性同位素。该项目涉及美国 GEOTRACES 太平洋探险队（从阿拉斯加到塔希提岛）测量钍元素的两种同位素。钍有与海洋中的颗粒结合的倾向，因此它可以用来测量其他元素从海洋表面的沉降情况。半衰期短的钍同位素可用于跟踪在较快时间尺度（数周或季节）内发生的过程，例如与海洋表层水中的生物学相关的过程，而半衰期较长的同位素可用于研究在较长时间尺度上发生的过程，如海洋环流。该项目将使用半衰期分别为 24.1 天和 1.9 年的钍 234 和钍 228 的测量来估计上层海洋中钍和其他元素的下沉速率。该提案分为四项主要活动： 1）使用短寿命的 Th-234 来估计粒子输出和再矿化率； 2) 使用 Th-234 与主要生物相（例如碳、氮、生物硅）和微量元素（例如铁、锰等）的比率来导出其他主要和微量元素的通量分布； 3) 使用 Th-228 延长出口和再矿化率的时间/深度； 4) 检查 #1-3 的变化与颗粒浓度和类型的预期梯度、浮游生物群落变化、群落净生产、气溶胶输入/灰尘、物理强迫（例如上升流）、热液羽流以及该 GEOTRACES 横断面的其他特征之间的关系。总 Th-234:U-238 的剖面提供了 Th-234 通量与深度的定量估计，它与 Th-234 和 TEI 的平行尺寸分级颗粒剖面一起使我们能够凭经验计算任何 TEI 的净颗粒输出的垂直剖面。通过高分辨率垂直和空间采样，Th-234 的应用可以扩展到海洋表层净去除区域以下，包括对上层数百米的颗粒输出和再矿化进行量化。根据之前的研究，Th-234 通量模型需要针对物理传输进行调整，尤其是跨越赤道的上升流。选定的 Th-228 剖面可以在深度和更长的时间尺度上进一步扩展这些通量和再矿化估计。该项目将支持一名博士学位。学生。

项目成果

The GEOTRACES Intermediate Data Product 2017

• DOI: 10.1016/j.chemgeo.2018.05.040
• 发表时间: 2018-08
• 期刊: Chemical Geology
• 影响因子: 3.9
• 作者: R. Schlitzer;R. Anderson;Elena Masferrer Dodas;M. Lohan;W. Geibert;A. Tagliabue;A. Bowie;C. Jeandel;M. T. Maldonado;W. Landing;Donna Cockwell;Cyril Abadie;W. Abouchami;E. Achterberg;A. Agather;Ana Aguliar-Islas;H. V. Aken;M. B. Andersen;C. Archer;M. Auro;H. Baar;O. Baars;A. Baker;K. Bakker;C. Basak;M. Baskaran;N. Bates;D. Bauch;P. Beek;M. Behrens;Erin E. Black;K. Bluhm;L. Bopp;H. Bouman;K. Bowman;J. Bown;P. Boyd;M. Boyé;E. Boyle;Pierre Branellec;Luke Bridgestock;G. Brissebrat;T. Browning;K. Bruland;H. Brumsack;M. Brzezinski;C. Buck;K. Buck;K. Buesseler;Abby Bull;E. Butler;P. Cai;P. Mor;D. Cardinal;C. Carlson;Gonzalo Carrasco;N. Casacuberta;K. Casciotti;M. Castrillejo;E. Chamizo;R. Chance;M. Charette;J. Chaves;Hai-Lan Cheng;F. Chever;M. Christl;T. Church;I. Closset;A. Colman;T. Conway;D. Cossa;P. Croot;J. Cullen;G. Cutter;C. Daniels;F. Dehairs;Feifei Deng;Huong Thi Dieu;B. Duggan;G. Dulaquais;C. Dumousseaud;Yolanda Echegoyen-Sanz;R. Edwards;M. Ellwood;E. Fahrbach;J. Fitzsimmons;A. Flegal;M. Fleisher;T. Flierdt;M. Frank;J. Friedrich;F. Fripiat;H. Fröllje;S. Galer;T. Gamo;R. Ganeshram;J. García-Orellana;E. Garcia-Solsona;M. Gault‐Ringold;E. George;L. Gerringa;M. Gilbert;J. Godoy;S. Goldstein;S. R. Gonzalez;K. Grissom;C. R. Hammerschmidt;A. E. Hartman;C. Hassler;E. Hathorne;M. Hatta;N. Hawco;C. T. Hayes;L. Heimbürger;Joshua Helgoe;M. Heller;G. Henderson;P. Henderson;S. Heuven;Peng Ho;T. Horner;Y. Hsieh;Kuo‐Fang Huang;M. Humphreys;K. Isshiki;Jeremy E. Jacquot;D. J. Janssen;W. Jenkins;S. John;E. Jones;Janice L. Jones;D. Kadko;Rick Kayser;T. Kenna;R. Khondoker;Taejin Kim;L. Kipp;J. Klar;M. Klunder;S. Kretschmer;Y. Kumamoto;P. Laan;M. Labatut;F. Lacan;P. Lam;M. Lambelet;C. Lamborg;F. L. Moigne;E. L. Roy;O. Lechtenfeld;Jong‐Mi Lee;P. Lherminier;S. Little;M. López-Lora;Yanbin Lu;P. Masqué;Edward Mawji;C. McClain;C. Measures;S. Mehic;J. M. Barraqueta;P. Merwe;R. Middag;S. Mieruch;A. Milne;Tomoharu Minami;J. Moffett;G. Moncoiffe;W. Moore;P. Morris;P. Morton;Y. Nakaguchi;N. Nakayama;J. Niedermiller;J. Nishioka;Akira Nishiuchi;A. Noble;H. Obata;S. Ober;D. Ohnemus;J. Ooijen;J. O'Sullivan;S. Owens;K. Pahnke;M. Paul;F. Pavia;L. Pena;B. Peters;F. Planchon;H. Planquette;C. Pradoux;Viena Puigcorbé;P. Quay;F. Quéroué;A. Radic;S. Rauschenberg;M. Rehkämper;R. Rember;T. Remenyi;J. Resing;J. Rickli;S. Rigaud;M. Rijkenberg;S. Rintoul;L. Robinson;M. Roca-Martí;V. Rodellas;Tobias Roeske;J. Rolison;M. Rosenberg;S. Roshan;M. Loeff;E. Ryabenko;M. Saito;L. Salt;V. Sanial;G. Sarthou;Christina Schallenberg;U. Schauer;H. Scher;C. Schlosser;B. Schnetger;Peter Scott;P. Sedwick;I. Semiletov;R. Shelley;R. Sherrell;A. Shiller;D. Sigman;Sunil Kumar Singh;H. Slagter;Emma Slater;W. Smethie;H. Snaith;Y. Sohrin;B. Sohst;J. Sonke;S. Speich;R. Steinfeldt;G. Stewart;T. Stichel;C. Stirling;J. Stutsman;G. Swarr;J. Swift;Alexander L. Thomas;K. Thorne;Claire P. Till;Ralph Till;A. Townsend;Emily Townsend;R. Tuerena;B. Twining;D. Vance;Sue Velazquez;C. Venchiarutti;M. Villa-Alfageme;Sebastián M. Vivancos;A. Voelker;B. Wake;M. Warner;R. Watson;E. V. Weerlee;M. A. Weigand;Y. Weinstein;D. Weiss;A. Wisotzki;E. Woodward;Jingfeng Wu;Yingzhe Wu;K. Wuttig;N. Wyatt;Yang Xiang;R. Xie;Z. Xue;Hisayuki Yoshikawa;Jing Zhang;Pu Zhang;Ye Zhao;Linjie Zheng;Xin-Yuan Zheng;M. Zieringer;L. Zimmer;P. Ziveri;P. Zunino;C. Zurbrick

Flux of Particulate Elements in the North Atlantic Ocean Constrained by Multiple Radionuclides

受多种放射性核素约束的北大西洋颗粒元素通量

• DOI: 10.1029/2018gb005994
• 发表时间: 2018
• 期刊: Global Biogeochemical Cycles
• 影响因子: 5.2
• 作者: Hayes, Christopher T.;Black, Erin E.;Anderson, Robert F.;Baskaran, Mark;Buesseler, Ken O.;Charette, Matthew A.;Cheng, Hai;Cochran, J. Kirk;Edwards, R. Lawrence;Fitzgerald, Patrick
• 通讯作者: Fitzgerald, Patrick