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项目的目标是了解海洋中微量化学元素及其同位素的分布。GEOTRACES的核心方法包括协调考察，测量海洋中关键梯度上的多种微量元素和同位素（TEIs），如生产力、氧化还原/氧、边界清除强度和热液活动的变化。然而，微量元素分布不足以满足GEOTRACES的目标，即“确定控制海洋中tei分布的过程和量化通量，并确定这些变化分布对环境条件的敏感性”。测量过程的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探险队在太平洋从阿拉斯加到塔希提岛的两种钍元素同位素的测量。钍倾向于与海洋中的粒子联系在一起，因此它可以用来测量其他元素从海洋表面下沉的情况。半衰期短的钍同位素可用于跟踪发生在较短时间尺度（周或季节）上的过程，例如与海洋表面水域的生物有关的过程，而半衰期较长的同位素可用于研究发生在较长时间尺度上的过程，例如海洋环流。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的测量值来估计钍和其他元素在上层海洋中的下沉速度。该建议分为四个主要活动：1)使用寿命短的Th-234来估计颗粒出口和再矿化率；2)利用Th-234与主要生物成因相（如碳、氮、生物成因二氧化硅）和微量元素（如铁、锰等）的比值，得出其他主要和微量元素的通量曲线；3)利用Th-228延长出口和再矿率的时间/深度；4)研究#1-3的变化如何与颗粒浓度和类型的预期梯度、浮游生物群落转移、净群落生产、气溶胶输入/尘埃、物理强迫（如上升流）、热液羽流和沿此GEOTRACES样带的其他特征相关。总Th-234剖面：U-238提供了Th-234通量随深度的定量估计，它与Th-234和TEI的平行尺寸分异颗粒剖面一起，使我们能够经验性地计算任何TEI的净颗粒出口垂直剖面。通过高分辨率的垂直和空间采样，Th-234的应用可以扩展到海洋表面净去除区以下，包括数百米以上颗粒出口和再矿化的量化。基于先前的研究，Th-234通量模型需要对物理传输进行调整，特别是赤道上的上升流。选定的Th-228剖面可以进一步扩展这些通量和再矿化估计，甚至在深度和更长的时间尺度上。该项目将资助一名博士生。

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