John Seth G.

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John
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Seth G.
ORCID
0000-0002-8257-626X

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  • Article
    GEOTRACES IC1 (BATS) contamination-prone trace element isotopes Cd, Fe, Pb, Zn, Cu, and Mo intercalibration
    (Association for the Sciences of Limnology and Oceanography, 2012-09) Boyle, Edward A. ; John, Seth G. ; Abouchami, Wafa ; Adkins, Jess F. ; Echegoyen-Sanz, Yolanda ; Ellwood, Michael J. ; Flegal, A. Russell ; Fornace, Kyrstin L. ; Gallon, Celine ; Galer, Stephen J. G. ; Gault-Ringold, Melanie ; Lacan, Francois ; Radic, Amandine ; Rehkamper, Mark ; Rouxel, Olivier J. ; Sohrin, Yoshiki ; Stirling, Claudine H. ; Thompson, Claire ; Vance, Derek ; Xue, Zichen ; Zhao, Ye
    We report data on the isotopic composition of cadmium, copper, iron, lead, zinc, and molybdenum at the GEOTRACES IC1 BATS Atlantic intercalibration station. In general, the between lab and within-lab precisions are adequate to resolve global gradients and vertical gradients at this station for Cd, Fe, Pb, and Zn. Cd and Zn isotopes show clear variations in the upper water column and more subtle variations in the deep water; these variations are attributable, in part, to progressive mass fractionation of isotopes by Rayleigh distillation from biogenic uptake and/or adsorption. Fe isotope variability is attributed to heavier crustal dust and hydrothermal sources and light Fe from reducing sediments. Pb isotope variability results from temporal changes in anthropogenic source isotopic compositions and the relative contributions of U.S. and European Pb sources. Cu and Mo isotope variability is more subtle and close to analytical precision. Although the present situation is adequate for proceeding with GEOTRACES, it should be possible to improve the within-lab and between-lab precisions for some of these properties.
  • Preprint
    Iron persistence in a distal hydrothermal plume supported by dissolved–particulate exchange
    ( 2017-01) Fitzsimmons, Jessica N. ; John, Seth G. ; Marsay, Christopher M. ; Hoffman, Colleen L. ; Nicholas, Sarah L. ; Toner, Brandy M. ; German, Christopher R. ; Sherrell, Robert M.
    Hydrothermally-sourced dissolved metals have been recorded in all ocean basins. In the oceans’ largest known hydrothermal plume, extending westward across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same plume also exceed background concentrations, even 4000 km from the source. Both dissolved and particulate iron deepen by more than 350 m relative to 3He – a non-reactive tracer of hydrothermal input – crossing isopycnals. Manganese shows no similar descent. Individual plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5-10 m year-1. Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe(III) oxyhydroxides, while dissolved iron consists of nanoparticulate Fe(III) oxyhydroxides and an organically-complexed iron phase. The descent of plume dissolved iron is best explained by reversible exchange onto slowly sinking particles, likely mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles.
  • Article
    Expanding Tara oceans protocols for underway, ecosystemic sampling of the ocean-atmosphere interface during Tara Pacific expedition (2016-2018)
    (Frontiers Media, 2019-12-11) Gorsky, Gabriel ; Bourdin, Guillaume ; Lombard, Fabien ; Pedrotti, Maria Luiza ; Audrain, Samuel ; Bin, Nicolas ; Boss, Emmanuel S. ; Bowler, Chris ; Cassar, Nicolas ; Caudan, Loic ; Chabot, Genevieve ; Cohen, Natalie R. ; Cron, Daniel ; De Vargas, Colomban ; Dolan, John R. ; Douville, Eric ; Elineau, Amanda ; Flores, J. Michel ; Ghiglione, Jean-Francois ; Haëntjens, Nils ; Hertau, Martin ; John, Seth G. ; Kelly, Rachel L. ; Koren, Ilan ; Lin, Yajuan ; Marie, Dominique ; Moulin, Clémentine ; Moucherie, Yohann ; Pesant, Stephane ; Picheral, Marc ; Poulain, Julie ; Pujo-Pay, Mireille ; Reverdin, Gilles ; Romac, Sarah ; Sullivan, Mathew B. ; Trainic, Miri ; Tressol, Marc ; Troublé, Romain ; Vardi, Assaf ; Voolstra, Christian R. ; Wincker, Patrick ; Agostini, Sylvain ; Banaigs, Bernard ; Boissin, Emilie ; Forcioli, Didier ; Furla, Paola ; Galand, Pierre E. ; Gilson, Eric ; Reynaud, Stephanie ; Sunagawa, Shinichi ; Thomas, Olivier P. ; Vega Thurber, Rebecca ; Zoccola, Didier ; Planes, Serge ; Allemand, Denis ; Karsenti, Eric
    Interactions between the ocean and the atmosphere occur at the air-sea interface through the transfer of momentum, heat, gases and particulate matter, and through the impact of the upper-ocean biology on the composition and radiative properties of this boundary layer. The Tara Pacific expedition, launched in May 2016 aboard the schooner Tara, was a 29-month exploration with the dual goals to study the ecology of reef ecosystems along ecological gradients in the Pacific Ocean and to assess inter-island and open ocean surface plankton and neuston community structures. In addition, key atmospheric properties were measured to study links between the two boundary layer properties. A major challenge for the open ocean sampling was the lack of ship-time available for work at “stations”. The time constraint led us to develop new underway sampling approaches to optimize physical, chemical, optical, and genomic methods to capture the entire community structure of the surface layers, from viruses to metazoans in their oceanographic and atmospheric physicochemical context. An international scientific consortium was put together to analyze the samples, generate data, and develop datasets in coherence with the existing Tara Oceans database. Beyond adapting the extensive Tara Oceans sampling protocols for high-resolution underway sampling, the key novelties compared to Tara Oceans’ global assessment of plankton include the measurement of (i) surface plankton and neuston biogeography and functional diversity; (ii) bioactive trace metals distribution at the ocean surface and metal-dependent ecosystem structures; (iii) marine aerosols, including biological entities; (iv) geography, nature and colonization of microplastic; and (v) high-resolution underway assessment of net community production via equilibrator inlet mass spectrometry. We are committed to share the data collected during this expedition, making it an important resource important resource to address a variety of scientific questions.
  • Dataset
    Dissolved concentrations of nickel and copper from bottle samples collected on Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-12-19) Bian, Xiaopeng ; Yang, Shun-Chung ; John, Seth G.
    This dataset contains dissolved concentrations of nickel (Ni) and copper (Cu) from bottle samples. The samples were collected during the U.S. GEOTRACES PMT cruise aboard the R/V Roger Revelle (RR1815 from October 24th to November 23rd of 2018). The dataset also includes station number, date, time, latitude, longitude, event number, event description, sample number, depth, and data quality flag. The data from Leg 1 of this transect, RR1814, are available as a related dataset. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/885335
  • Dataset
    Dissolved concentrations of nickel and copper from bottle samples collected on Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-12-19) Bian, Xiaopeng ; Yang, Shun-Chung ; John, Seth G.
    This dataset contains dissolved concentrations of nickel (Ni) and copper (Cu) from bottle samples. The samples were collected during the U.S. GEOTRACES PMT cruise aboard the R/V Roger Revelle (RR1814 from September 18th to October 21st of 2018). The dataset also includes station number, date, time, latitude, longitude, event number, event description, sample number, depth, and data quality flag. The data from Leg 2 of this transect, RR1815, are available as a related dataset. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/885319
  • Dataset
    Isotopic composition and concentrations of dissolved and particulate nickel, cadmium, iron, zinc, and copper from the Eastern Tropical North Pacific Ocean on R/V Revelle cruise RR1804 and on R/V Sikuliaq cruise SKQ201617S
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-03-01) John, Seth G. ; Moffett, James W.
    Isotopic composition and concentrations of dissolved and particulate nickel, cadmium, iron, zinc, and copper from the Eastern Tropical North Pacific Ocean on R/V Revelle cruise RR1804 and on R/V Sikuliaq cruise SKQ201617S. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/842086
  • Article
    The acceleration of dissolved cobalt's ecological stoichiometry due to biological uptake, remineralization, and scavenging in the Atlantic Ocean
    (Copernicus Publications on behalf of the European Geosciences Union, 2017-10-20) Saito, Mak A. ; Noble, Abigail E. ; Hawco, Nicholas J. ; Twining, Benjamin S. ; Ohnemus, Daniel C. ; John, Seth G. ; Lam, Phoebe J. ; Conway, Tim M. ; Johnson, Rod ; Moran, Dawn M. ; McIlvin, Matthew R.
    The stoichiometry of biological components and their influence on dissolved distributions have long been of interest in the study of the oceans. Cobalt has the smallest oceanic inventory of inorganic micronutrients and hence is particularly vulnerable to influence by internal oceanic processes including euphotic zone uptake, remineralization, and scavenging. Here we observe not only large variations in dCo : P stoichiometry but also the acceleration of those dCo : P ratios in the upper water column in response to several environmental processes. The ecological stoichiometry of total dissolved cobalt (dCo) was examined using data from a US North Atlantic GEOTRACES transect and from a zonal South Atlantic GEOTRACES-compliant transect (GA03/3_e and GAc01) by Redfieldian analysis of its statistical relationships with the macronutrient phosphate. Trends in the dissolved cobalt to phosphate (dCo : P) stoichiometric relationships were evident in the basin-scale vertical structure of cobalt, with positive dCo : P slopes in the euphotic zone and negative slopes found in the ocean interior and in coastal environments. The euphotic positive slopes were often found to accelerate towards the surface and this was interpreted as being due to the combined influence of depleted phosphate, phosphorus-sparing (conserving) mechanisms, increased alkaline phosphatase metalloenzyme production (a zinc or perhaps cobalt enzyme), and biochemical substitution of Co for depleted Zn. Consistent with this, dissolved Zn (dZn) was found to be drawn down to only 2-fold more than dCo, despite being more than 18-fold more abundant in the ocean interior. Particulate cobalt concentrations increased in abundance from the base of the euphotic zone to become  ∼  10 % of the overall cobalt inventory in the upper euphotic zone with high stoichiometric values of  ∼  400 µmol Co mol−1 P. Metaproteomic results from the Bermuda Atlantic Time-series Study (BATS) station found cyanobacterial isoforms of the alkaline phosphatase enzyme to be prevalent in the upper water column, as well as a sulfolipid biosynthesis protein indicative of P sparing. The negative dCo : P relationships in the ocean interior became increasingly vertical with depth, and were consistent with the sum of scavenging and remineralization processes (as shown by their dCo : P vector sums). Attenuation of the remineralization with depth resulted in the increasingly vertical dCo : P relationships. Analysis of particulate Co with particulate Mn and particulate phosphate also showed positive linear relationships below the euphotic zone, consistent with the presence and increased relative influence of Mn oxide particles involved in scavenging. Visualization of dCo : P slopes across an ocean section revealed hotspots of scavenging and remineralization, such as at the hydrothermal vents and below the oxygen minimum zone (OMZ) region, respectively, while that of an estimate of Co* illustrated stoichiometrically depleted values in the mesopelagic and deep ocean due to scavenging. This study provides insights into the coupling between the dissolved and particulate phase that ultimately creates Redfield stoichiometric ratios, demonstrating that the coupling is not an instantaneous process and is influenced by the element inventory and rate of exchange between phases. Cobalt's small water column inventory and the influence of external factors on its biotic stoichiometry can erode its limited inertia and result in an acceleration of the dissolved stoichiometry towards that of the particulate phase in the upper euphotic zone. As human use of cobalt grows exponentially with widespread adoption of lithium ion batteries, there is a potential to affect the limited biogeochemical inertia of cobalt and its resultant ecology in the oceanic euphotic zone.
  • Article
    Iron depletion in the deep chlorophyll maximum: mesoscale eddies as natural iron fertilization experiments
    (American Geophysical Union, 2021-11-17) Hawco, Nicholas J. ; Barone, Benedetto ; Church, Matthew J. ; Babcock-Adams, Lydia ; Repeta, Daniel J. ; Wear, Emma K. ; Foreman, Rhea K. ; Björkman, Karin M. ; Bent, Shavonna M. ; Van Mooy, Benjamin A. S. ; Sheyn, Uri ; DeLong, Edward F. ; Acker, Marianne ; Kelly, Rachel L. ; Nelson, Alexa ; Ranieri, John ; Clemente, Tara M. ; Karl, David M. ; John, Seth G.
    In stratified oligotrophic waters, phytoplankton communities forming the deep chlorophyll maximum (DCM) are isolated from atmospheric iron sources above and remineralized iron sources below. Reduced supply leads to a minimum in dissolved iron (dFe) near 100 m, but it is unclear if iron limits growth at the DCM. Here, we propose that natural iron addition events occur regularly with the passage of mesoscale eddies, which alter the supply of dFe and other nutrients relative to the availability of light, and can be used to test for iron limitation at the DCM. This framework is applied to two eddies sampled in the North Pacific Subtropical Gyre. Observations in an anticyclonic eddy center indicated downwelling of iron-rich surface waters, leading to increased dFe at the DCM but no increase in productivity. In contrast, uplift of isopycnals within a cyclonic eddy center increased supply of both nitrate and dFe to the DCM, and led to dominance of picoeukaryotic phytoplankton. Iron addition experiments did not increase productivity in either eddy, but significant enhancement of leucine incorporation in the light was observed in the cyclonic eddy, a potential indicator of iron stress among Prochlorococcus. Rapid cycling of siderophores and low dFe:nitrate uptake ratios also indicate that a portion of the microbial community was stressed by low iron. However, near-complete nitrate drawdown in this eddy, which represents an extreme case in nutrient supply compared to nearby Hawaii Ocean Time-series observations, suggests that recycling of dFe in oligotrophic ecosystems is sufficient to avoid iron limitation in the DCM under typical conditions.
  • Article
    Elevated sources of cobalt in the Arctic Ocean
    (European Geosciences Union, 2020-10-01) Bundy, Randelle M. ; Tagliabue, Alessandro ; Hawco, Nicholas J. ; Morton, Peter L. ; Twining, Benjamin S. ; Hatta, Mariko ; Noble, Abigail E. ; Cape, Mattias R. ; John, Seth G. ; Cullen, Jay T. ; Saito, Mak A.
    Cobalt (Co) is an important bioactive trace metal that is the metal cofactor in cobalamin (vitamin B12) which can limit or co-limit phytoplankton growth in many regions of the ocean. Total dissolved and labile Co measurements in the Canadian sector of the Arctic Ocean during the U.S. GEOTRACES Arctic expedition (GN01) and the Canadian International Polar Year GEOTRACES expedition (GIPY14) revealed a dynamic biogeochemical cycle for Co in this basin. The major sources of Co in the Arctic were from shelf regions and rivers, with only minimal contributions from other freshwater sources (sea ice, snow) and eolian deposition. The most striking feature was the extremely high concentrations of dissolved Co in the upper 100 m, with concentrations routinely exceeding 800 pmol L−1 over the shelf regions. This plume of high Co persisted throughout the Arctic basin and extended to the North Pole, where sources of Co shifted from primarily shelf-derived to riverine, as freshwater from Arctic rivers was entrained in the Transpolar Drift. Dissolved Co was also strongly organically complexed in the Arctic, ranging from 70 % to 100 % complexed in the surface and deep ocean, respectively. Deep-water concentrations of dissolved Co were remarkably consistent throughout the basin (∼55 pmol L−1), with concentrations reflecting those of deep Atlantic water and deep-ocean scavenging of dissolved Co. A biogeochemical model of Co cycling was used to support the hypothesis that the majority of the high surface Co in the Arctic was emanating from the shelf. The model showed that the high concentrations of Co observed were due to the large shelf area of the Arctic, as well as to dampened scavenging of Co by manganese-oxidizing (Mn-oxidizing) bacteria due to the lower temperatures. The majority of this scavenging appears to have occurred in the upper 200 m, with minimal additional scavenging below this depth. Evidence suggests that both dissolved Co (dCo) and labile Co (LCo) are increasing over time on the Arctic shelf, and these limited temporal results are consistent with other tracers in the Arctic. These elevated surface concentrations of Co likely lead to a net flux of Co out of the Arctic, with implications for downstream biological uptake of Co in the North Atlantic and elevated Co in North Atlantic Deep Water. Understanding the current distributions of Co in the Arctic will be important for constraining changes to Co inputs resulting from regional intensification of freshwater fluxes from ice and permafrost melt in response to ongoing climate change.
  • Article
    GNOM v1.0: an optimized steady-state model of the modern marine neodymium cycle
    (European Geosciences Union, 2022-06-16) Pasquier, Benoît ; Hines, Sophia K. ; Liang, Hengdi ; Wu, Yingzhe ; Goldstein, Steven L. ; John, Seth G.
    Spatially distant sources of neodymium (Nd) to the ocean that carry different isotopic signatures (εNd) have been shown to trace out major water masses and have thus been extensively used to study large-scale features of the ocean circulation both past and current. While the global marine Nd cycle is qualitatively well understood, a complete quantitative determination of all its components and mechanisms, such as the magnitude of its sources and the paradoxical conservative behavior of εNd, remains elusive. To make sense of the increasing collection of observational Nd and εNd data, in this model description paper we present and describe the Global Neodymium Ocean Model (GNOM) v1.0, the first inverse model of the global marine biogeochemical cycle of Nd. The GNOM is embedded in a data-constrained steady-state circulation that affords spectacular computational efficiency, which we leverage to perform systematic objective optimization, allowing us to make preliminary estimates of biogeochemical parameters. Owing to its matrix representation, the GNOM model is additionally amenable to novel diagnostics that allow us to investigate open questions about the Nd cycle with unprecedented accuracy. This model is open-source and freely accessible, is written in Julia, and its code is easily understandable and modifiable for further community developments, refinements, and experiments.
  • Article
    Recycling of dissolved iron in the North Pacific Subtropical Gyre
    (Association for the Sciences of Limnology and Oceanography, 2022-09-08) Hawco, Nicholas J. ; Yang, Shun-Chung ; Pinedo-Gonzalez, Paulina ; Black, Erin E. ; Kenyon, Jennifer ; Ferrón, Sara ; Bian, Xiaopeng ; John, Seth G.
    The importance of iron as a limiting nutrient in the open ocean is widely recognized, but there is substantial uncertainty about the rate that it cycles in the marine environment. Here, we combine measurements from the water column, sediment traps, and incubations to constrain Fe turnover during summer at Station ALOHA in the North Pacific Subtropical Gyre. Using low levels of 57Fe–58Fe double spike, measured with high precision by multi-collector inductively coupled plasma mass spectrometry, we find Fe uptake rates of 30–60 pM d−1 throughout the euphotic zone. Dissolved Fe turnover times are estimated at 10–15 d in the mixed layer and 1–3 d near the deep chlorophyll maximum. Aerosol Fe supply inferred from a thorium isotope mass balance indicates that the dissolved Fe residence time is approximately 6 months in the upper euphotic zone (0–75 m), relative to external sources, and 2 months in the lower euphotic zone (75–150 m). To reconcile these observations, the average Fe atom must be recycled over 25 times at Station ALOHA in both the upper and lower euphotic zones (an “Fe ratio” equal to 0.04 and 0.03, respectively), a level of conservation that has only been documented in Fe-limited regions thus far. At steady state, this scenario requires an aerosol Fe solubility of 4.5%, which is similar to dissolution experiments from Pacific Ocean aerosols. Our results suggest that the oligotrophic ocean is capable of recycling iron efficiently even when these ecosystems are not demonstrably iron-limited.
  • Article
    The GEOTRACES Intermediate Data Product 2014
    (Elsevier, 2015-04-16) Mawji, Edward ; Schlitzer, Reiner ; Dodas, Elena Masferrer ; Abadie, Cyril ; Abouchami, Wafa ; Anderson, Robert F. ; Baars, Oliver ; Bakker, Karel ; Baskaran, Mark ; Bates, Nicholas R. ; Bluhm, Katrin ; Bowie, Andrew R. ; Bown, Johann ; Boye, Marie ; Marie, Edward A. ; Branellec, Pierre ; Bruland, Kenneth W. ; Brzezinski, Mark A. ; Bucciarelli, Eva ; Buesseler, Ken O. ; Butler, Edward ; Cai, Pinghe ; Cardinal, Damien ; Casciotti, Karen L. ; Chaves, Joaquin E. ; Cheng, Hai ; Chever, Fanny ; Church, Thomas M. ; Colman, Albert S. ; Conway, Tim M. ; Croot, Peter L. ; Cutter, Gregory A. ; Baar, Hein J. W. de ; de Souza, Gregory F. ; Dehairs, Frank ; Deng, Feifei ; Dieu, Huong Thi ; Dulaquais, Gabriel ; Echegoyen-Sanz, Yolanda ; Edwards, R. Lawrence ; Fahrbach, Eberhard ; Fitzsimmons, Jessica N. ; Fleisher, Martin Q. ; Frank, Martin ; Friedrich, Jana ; Fripiat, Francois ; Galer, Stephen J. G. ; Gamo, Toshitaka ; Garcia Solsona, Ester ; Gerringa, Loes J. A. ; Godoy, Jose Marcus ; Gonzalez, Santiago ; Grossteffan, Emilie ; Hatta, Mariko ; Hayes, Christopher T. ; Heller, Maija Iris ; Henderson, Gideon M. ; Huang, Kuo-Fang ; Jeandel, Catherine ; Jenkins, William J. ; John, Seth G. ; Kenna, Timothy C. ; Klunder, Maarten ; Kretschmer, Sven ; Kumamoto, Yuichiro ; Laan, Patrick ; Labatut, Marie ; Lacan, Francois ; Lam, Phoebe J. ; Lannuzel, Delphine ; le Moigne, Frederique ; Lechtenfeld, Oliver J. ; Lohan, Maeve C. ; Lu, Yanbin ; Masqué, Pere ; McClain, Charles R. ; Measures, Christopher I. ; Middag, Rob ; Moffett, James W. ; Navidad, Alicia ; Nishioka, Jun ; Noble, Abigail E. ; Obata, Hajime ; Ohnemus, Daniel C. ; Owens, Stephanie A. ; Planchon, Frederic ; Pradoux, Catherine ; Puigcorbe, Viena ; Quay, Paul D. ; Radic, Amandine ; Rehkamper, Mark ; Remenyi, Tomas A. ; Rijkenberg, Micha J. A. ; Rintoul, Stephen R. ; Robinson, Laura F. ; Roeske, Tobias ; Rosenberg, Mark ; Rutgers van der Loeff, Michiel M. ; Ryabenko, Evgenia ; Saito, Mak A. ; Roshan, Saeed ; Salt, Lesley ; Sarthou, Geraldine ; Schauer, Ursula ; Scott, Peter M. ; Sedwick, Peter N. ; Sha, Lijuan ; Shiller, Alan M. ; Sigman, Daniel M. ; Smethie, William M. ; Smith, Geoffrey J. ; Sohrin, Yoshiki ; Speich, Sabrina ; Stichel, Torben ; Stutsman, Johnny ; Swift, James H. ; Tagliabue, Alessandro ; Thomas, Alexander L. ; Tsunogai, Urumu ; Twining, Benjamin S. ; van Aken, Hendrik M. ; van Heuven, Steven ; van Ooijen, Jan ; van Weerlee, Evaline ; Venchiarutti, Celia ; Voelker, Antje H. L. ; Wake, Bronwyn ; Warner, Mark J. ; Woodward, E. Malcolm S. ; Wu, Jingfeng ; Wyatt, Neil ; Yoshikawa, Hisayuki ; Zheng, Xin-Yuan ; Xue, Zichen ; Zieringer, Moritz ; Zimmer, Louise A.
    The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEIs) as well as classical hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing a strongly inter-linked on-line atlas including more than 300 section plots and 90 animated 3D scenes. The IDP2014 covers the Atlantic, Arctic, and Indian oceans, exhibiting highest data density in the Atlantic. The TEI data in the IDP2014 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at cross-over stations. The digital data are provided in several formats, including ASCII spreadsheet, Excel spreadsheet, netCDF, and Ocean Data View collection. In addition to the actual data values the IDP2014 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering. Metadata about data originators, analytical methods and original publications related to the data are linked to the data in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2014 data providing section plots and a new kind of animated 3D scenes. The basin-wide 3D scenes allow for viewing of data from many cruises at the same time, thereby providing quick overviews of large-scale tracer distributions. In addition, the 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of observed tracer plumes, as well as for making inferences about controlling processes.
  • Article
    The transpolar drift as a source of riverine and shelf-derived trace elements to the central Arctic Ocean
    (American Geophysical Union, 2020-04-08) Charette, Matthew A. ; Kipp, Lauren ; Jensen, Laramie T. ; Dabrowski, Jessica S. ; Whitmore, Laura M. ; Fitzsimmons, Jessica N. ; Williford, Tatiana ; Ulfsbo, Adam ; Jones, Elizabeth M. ; Bundy, Randelle M. ; Vivancos, Sebastian M. ; Pahnke, Katharina ; John, Seth G. ; Xiang, Yang ; Hatta, Mariko ; Petrova, Mariia V. ; Heimbürger, Lars-Eric ; Bauch, Dorothea ; Newton, Robert ; Pasqualini, Angelica ; Agather, Alison ; Amon, Rainer M. W. ; Anderson, Robert F. ; Andersson, Per S. ; Benner, Ronald ; Bowman, Katlin ; Edwards, R. Lawrence ; Gdaniec, Sandra ; Gerringa, Loes J. A. ; González, Aridane G. ; Granskog, Mats A. ; Haley, Brian ; Hammerschmidt, Chad R. ; Hansell, Dennis A. ; Henderson, Paul B. ; Kadko, David C. ; Kaiser, Karl ; Laan, Patrick ; Lam, Phoebe J. ; Lamborg, Carl H. ; Levier, Martin ; Li, Xianglei ; Margolin, Andrew R. ; Measures, Christopher I. ; Middag, Rob ; Millero, Frank J. ; Moore, Willard S. ; Paffrath, Ronja ; Planquette, Helene ; Rabe, Benjamin ; Reader, Heather ; Rember, Robert ; Rijkenberg, Micha J. A. ; Roy-Barman, Matthieu ; van der Loeff, Michiel Rutgers ; Saito, Mak A. ; Schauer, Ursula ; Schlosser, Peter ; Sherrell, Robert M. ; Shiller, Alan M. ; Slagter, Hans ; Sonke, Jeroen E. ; Stedmon, Colin ; Woosley, Ryan J. ; Valk, Ole ; van Ooijen, Jan ; Zhang, Ruifeng
    A major surface circulation feature of the Arctic Ocean is the Transpolar Drift (TPD), a current that transports river‐influenced shelf water from the Laptev and East Siberian Seas toward the center of the basin and Fram Strait. In 2015, the international GEOTRACES program included a high‐resolution pan‐Arctic survey of carbon, nutrients, and a suite of trace elements and isotopes (TEIs). The cruises bisected the TPD at two locations in the central basin, which were defined by maxima in meteoric water and dissolved organic carbon concentrations that spanned 600 km horizontally and ~25–50 m vertically. Dissolved TEIs such as Fe, Co, Ni, Cu, Hg, Nd, and Th, which are generally particle‐reactive but can be complexed by organic matter, were observed at concentrations much higher than expected for the open ocean setting. Other trace element concentrations such as Al, V, Ga, and Pb were lower than expected due to scavenging over the productive East Siberian and Laptev shelf seas. Using a combination of radionuclide tracers and ice drift modeling, the transport rate for the core of the TPD was estimated at 0.9 ± 0.4 Sv (106 m3 s−1). This rate was used to derive the mass flux for TEIs that were enriched in the TPD, revealing the importance of lateral transport in supplying materials beneath the ice to the central Arctic Ocean and potentially to the North Atlantic Ocean via Fram Strait. Continued intensification of the Arctic hydrologic cycle and permafrost degradation will likely lead to an increase in the flux of TEIs into the Arctic Ocean.
  • Preprint
    Divergent responses of Atlantic coastal and oceanic Synechococcus to iron limitation
    ( 2015-06-19) Mackey, Katherine R. M. ; Post, Anton F. ; McIlvin, Matthew R. ; Cutter, Gregory A. ; John, Seth G. ; Saito, Mak A.
    Marine Synechococcus are some of the most diverse and ubiquitous phytoplankton, and iron (Fe) is an essential micronutrient that limits productivity in many parts of the ocean. To investigate how coastal and oceanic Atlantic Synechococcus strains acclimate to Fe availability, we compared the growth, photophysiology, and quantitative proteomics of two Synechococcus strains from different Fe regimes. Synechococcus strain WH8102, from a region in the southern Sargasso Sea that receives substantial dust deposition, showed impaired growth and photophysiology as Fe declined, yet utilized few acclimation responses. Coastal WH8020, from the dynamic, seasonally variable New England shelf, displayed a multi-tiered, hierarchical cascade of acclimation responses with different Fe thresholds. The multi-tiered response included changes in Fe acquisition, storage, and photosynthetic proteins, substitution of flavodoxin for ferredoxin, and modified photophysiology, all while maintaining remarkably stable growth rates over a range of Fe concentrations. Modulation of two distinct ferric uptake regulator (Fur) proteins that coincided with the multi-tiered proteome response was found, implying the coastal strain has different regulatory threshold responses to low Fe availability. Low nitrogen (N) and phosphorus (P) availability in the open ocean may favor the loss of Fe response genes when Fe availability is consistent over time, whereas these genes are retained in dynamic environments where Fe availability fluctuates and N and P are more abundant.
  • Dataset
    Concentrations of dissolved cadmium, nickel, manganese, lanthanum, cerium, praseodymium, and neodymium from the Eastern Tropical North Pacific Ocean on R/V Revelle cruise RR1804-1805 (OMZ Nutrient Cycling project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-05-27) John, Seth G. ; Bian, Xiaopeng ; Moffett, James W.
    Oxygen deficient zones (ODZs) play an important role in the distribution and cycling of trace metals in the ocean, as important sources of metals including Fe and Mn to the ocean, and also as possible sinks of chalcophile elements such as Cd. The Eastern Tropical North Pacific (ETNP) ODZ is one of the three largest ODZs worldwide. Here we present results from two sectional surveys through the ETNP ODZ (23N-14N, 105W-130W) conducted during two cruises of the R/V Roger Revelle, RR1804 and RR1805, from March to April 2018, providing a high-resolution concentrations of dissolved Cd, Ni, Mn, La, Ce, Pr, and Nd in seawater. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872434
  • Thesis
    The marine biogeochemistry of zinc isotopes
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-06) John, Seth G.
    Zinc (Zn) stable isotopes can record information about important oceanographic processes. This thesis presents data on Zn isotopes in anthropogenic materials, hydrothermal fluids and minerals, cultured marine phytoplankton, natural plankton, and seawater. By measuring Zn isotopes in a diverse array of marine samples, we hope to understand how Zn isotopes are fractionated in the oceans and how Zn isotopes may be used as tracers of marine biogeochemical processes. Common forms of anthropogenic Zn had δ66Zn from +0.08‰ to +0.32‰, a range similar to Zn ores and terrigenous materials. Larger variations were discovered in hydrothermal fluids and minerals, with hydrothermal fluids ranging in δ66Zn from 0.02‰ to +0.93‰, and chimney minerals ranging from -0.09‰ to +1.17‰. Lower-temperature vent systems had higher δ66Zn values, suggesting that precipitation of isotopically light Zn sulfides drives much of the Zn isotope fractionation in hydrothermal systems. In cultured diatoms, a relationship was discovered between Zn transport by either high-affinity or low-affinity uptake pathways, and the magnitude of Zn isotope fractionation. We established isotope effects of δ66Zn = -0.2‰ for high-affinity uptake and δ66Zn = -0.8‰ for low-affinity uptake. This work is the first to describe the molecular basis for biological fractionation of transition metals. Biological fractionation of Zn isotopes under natural conditions was investigated by measuring Zn isotopes in plankton collected in the Peru Upwelling Region and around the world. Seawater dissolved Zn isotopes also reflect the chemical and biological cycling of Zn. The δ66Zn of deep seawater in the North Pacific and North Atlantic is about 0.5‰, and the dissolved δ66Zn gets lighter in the upper water column. This is unexpected based our observations of a biological preference for uptake of light Zn isotopes, and suggests that Zn transport to deep waters may occur by Zn adsorption to sinking particles rather than as primary biological Zn. The thesis, by presenting data on several important aspects of Zn isotope cycling in the oceans, lays the groundwork for further use of Zn isotopes as a marine biogeochemical tracer.
  • Dataset
    Dissolved concentrations and stable isotope ratios of Fe, Zn, and Cd from Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-12-22) Conway, Timothy M. ; John, Seth G. ; Sieber, Matthias
    This dataset reports dissolved (0.2µm AcroPak filter) concentrations and stable isotope ratios of iron, zinc, and cadmium (Fe, Zn, and Cd) via Nobias PA-1 extraction and MC-ICPMS analysis in water samples collected by the GTC (GEOTRACES Trace-metal clean CTD carousel) and/or surface tow fish from 23 stations along the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) on R/V Roger Revelle from October to November 2018. The GP15 cruise sailed from September to November 2018 on a meridional transect along 152°W from Alaska to Tahiti. Concentration and isotope data were collected by Dr. Matthias Sieber and Dr. Tim Conway at the University of South Florida using a Thermo Neptune Plus MC-ICPMS. Trace metal isotope ratios are an important tool to better understand the marine cycles of trace metals and their relationship to major nutrients. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/884673
  • Dataset
    Dissolved concentrations and stable isotope ratios of Fe, Zn, and Cd from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-12-22) Conway, Timothy M. ; John, Seth G. ; Sieber, Matthias
    This dataset reports dissolved (0.2µm AcroPak filter) concentrations and stable isotope ratios of iron, zinc, and cadmium (Fe, Zn, and Cd) via Nobias PA-1 extraction and MC-ICPMS analysis in water samples collected by the GTC (GEOTRACES Trace-metal clean CTD carousel) and/or surface tow fish from 23 stations along the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) on R/V Roger Revelle from September to October 2018. The GP15 cruise sailed from September to November 2018 on a meridional transect along 152°W from Alaska to Tahiti. Concentration and isotope data were collected by Dr. Matthias Sieber and Dr. Tim Conway at the University of South Florida using a Thermo Neptune Plus MC-ICPMS. Trace metal isotope ratios are an important tool to better understand the marine cycles of trace metals and their relationship to major nutrients. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/883862
  • Article
    The GEOTRACES Intermediate Data Product 2017
    (Elsevier, 2018-06-01) Schlitzer, Reiner ; Anderson, Robert F. ; Dodas, Elena Masferrer ; Lohan, Maeve C. ; Geibert, Walter ; Tagliabue, Alessandro ; Bowie, Andrew R. ; Jeandel, Catherine ; Maldonado, Maria T. ; Landing, William M. ; Cockwell, Donna ; Abadie, Cyril ; Abouchami, Wafa ; Achterberg, Eric P. ; Agather, Alison ; Aguliar-Islas, Ana ; van Aken, Hendrik M. ; Andersen, Morten ; Archer, Corey ; Auro, Maureen E. ; Baar, Hein J. W. de ; Baars, Oliver ; Baker, Alex R. ; Bakker, Karel ; Basak, Chandranath ; Baskaran, Mark ; Bates, Nicholas R. ; Bauch, Dorothea ; van Beek, Pieter ; Behrens, Melanie K. ; Black, Erin E. ; Bluhm, Katrin ; Bopp, Laurent ; Bouman, Heather ; Bowman, Katlin ; Bown, Johann ; Boyd, Philip ; Boye, Marie ; Boyle, Edward A. ; Branellec, Pierre ; Bridgestock, Luke ; Brissebrat, Guillaume ; Browning, Thomas ; Bruland, Kenneth W. ; Brumsack, Hans-Jürgen ; Brzezinski, Mark A. ; Buck, Clifton S. ; Buck, Kristen N. ; Buesseler, Ken O. ; Bull, Abby ; Butler, Edward ; Cai, Pinghe ; Cámara Mor, Patricia ; Cardinal, Damien ; Carlson, Craig ; Carrasco, Gonzalo ; Casacuberta, Nuria ; Casciotti, Karen L. ; Castrillejo, Maxi ; Chamizo, Elena ; Chance, Rosie ; Charette, Matthew A. ; Chaves, Joaquin E. ; Cheng, Hai ; Chever, Fanny ; Christl, Marcus ; Church, Thomas M. ; Closset, Ivia ; Colman, Albert S. ; Conway, Tim M. ; Cossa, Daniel ; Croot, Peter L. ; Cullen, Jay T. ; Cutter, Gregory A. ; Daniels, Chris ; Dehairs, Frank ; Deng, Feifei ; Dieu, Huong Thi ; Duggan, Brian ; Dulaquais, Gabriel ; Dumousseaud, Cynthia ; Echegoyen-Sanz, Yolanda ; Edwards, R. Lawrence ; Ellwood, Michael J. ; Fahrbach, Eberhard ; Fitzsimmons, Jessica N. ; Flegal, A. Russell ; Fleisher, Martin Q. ; van de Flierdt, Tina ; Frank, Martin ; Friedrich, Jana ; Fripiat, Francois ; Fröllje, Henning ; Galer, Stephen J. G. ; Gamo, Toshitaka ; Ganeshram, Raja S. ; Garcia-Orellana, Jordi ; Garcia Solsona, Ester ; Gault-Ringold, Melanie ; George, Ejin ; Gerringa, Loes J. A. ; Gilbert, Melissa ; Godoy, Jose Marcus ; Goldstein, Steven L. ; Gonzalez, Santiago ; Grissom, Karen ; Hammerschmidt, Chad R. ; Hartman, Alison ; Hassler, Christel ; Hathorne, Ed C. ; Hatta, Mariko ; Hawco, Nicholas J. ; Hayes, Christopher T. ; Heimbürger, Lars-Eric ; Helgoe, Josh ; Heller, Maija Iris ; Henderson, Gideon M. ; Henderson, Paul B. ; van Heuven, Steven ; Ho, Peng ; Horner, Tristan J. ; Hsieh, Yu-Te ; Huang, Kuo-Fang ; Humphreys, Matthew P. ; Isshiki, Kenji ; Jacquot, Jeremy E. ; Janssen, David J. ; Jenkins, William J. ; John, Seth ; Jones, Elizabeth M. ; Jones, Janice L. ; Kadko, David ; Kayser, Rick ; Kenna, Timothy C. ; Khondoker, Roulin ; Kim, Taejin ; Kipp, Lauren ; Klar, Jessica K. ; Klunder, Maarten ; Kretschmer, Sven ; Kumamoto, Yuichiro ; Laan, Patrick ; Labatut, Marie ; Lacan, Francois ; Lam, Phoebe J. ; Lambelet, Myriam ; Lamborg, Carl H. ; le Moigne, Frederique ; Le Roy, Emilie ; Lechtenfeld, Oliver J. ; Lee, Jong-Mi ; Lherminier, Pascale ; Little, Susan ; López-Lora, Mercedes ; Lu, Yanbin ; Masque, Pere ; Mawji, Edward ; McClain, Charles R. ; Measures, Christopher I. ; Mehic, Sanjin ; Menzel Barraqueta, Jan-Lukas ; Merwe, Pier van der ; Middag, Rob ; Mieruch, Sebastian ; Milne, Angela ; Minami, Tomoharu ; Moffett, James W. ; Moncoiffe, Gwenaelle ; Moore, Willard S. ; Morris, Paul J. ; Morton, Peter L. ; Nakaguchi, Yuzuru ; Nakayama, Noriko ; Niedermiller, John ; Nishioka, Jun ; Nishiuchi, Akira ; Noble, Abigail E. ; Obata, Hajime ; Ober, Sven ; Ohnemus, Daniel C. ; van Ooijen, Jan ; O'Sullivan, Jeanette ; Owens, Stephanie A. ; Pahnke, Katharina ; Paul, Maxence ; Pavia, Frank ; Pena, Leopoldo D. ; Peters, Brian ; Planchon, Frederic ; Planquette, Helene ; Pradoux, Catherine ; Puigcorbé, Viena ; Quay, Paul D. ; Queroue, Fabien ; Radic, Amandine ; Rauschenberg, Sara ; Rehkämper, Mark ; Rember, Robert ; Remenyi, Tomas A. ; Resing, Joseph A. ; Rickli, Joerg ; Rigaud, Sylvain ; Rijkenberg, Micha J. A. ; Rintoul, Stephen R. ; Robinson, Laura F. ; Roca-Martí, Montserrat ; Rodellas, Valenti ; Roeske, Tobias ; Rolison, John M. ; Rosenberg, Mark ; Roshan, Saeed ; Rutgers van der Loeff, Michiel M. ; Ryabenko, Evgenia ; Saito, Mak A. ; Salt, Lesley ; Sanial, Virginie ; Sarthou, Geraldine ; Schallenberg, Christina ; Schauer, Ursula ; Scher, Howie ; Schlosser, Christian ; Schnetger, Bernhard ; Scott, Peter M. ; Sedwick, Peter N. ; Semiletov, Igor P. ; Shelley, Rachel U. ; Sherrell, Robert M. ; Shiller, Alan M. ; Sigman, Daniel M. ; Singh, Sunil Kumar ; Slagter, Hans ; Slater, Emma ; Smethie, William M. ; Snaith, Helen ; Sohrin, Yoshiki ; Sohst, Bettina M. ; Sonke, Jeroen E. ; Speich, Sabrina ; Steinfeldt, Reiner ; Stewart, Gillian ; Stichel, Torben ; Stirling, Claudine H. ; Stutsman, Johnny ; Swarr, Gretchen J. ; Swift, James H. ; Thomas, Alexander ; Thorne, Kay ; Till, Claire P. ; Till, Ralph ; Townsend, Ashley T. ; Townsend, Emily ; Tuerena, Robyn ; Twining, Benjamin S. ; Vance, Derek ; Velazquez, Sue ; Venchiarutti, Celia ; Villa-Alfageme, Maria ; Vivancos, Sebastian M. ; Voelker, Antje H. L. ; Wake, Bronwyn ; Warner, Mark J. ; Watson, Ros ; van Weerlee, Evaline ; Weigand, M. Alexandra ; Weinstein, Yishai ; Weiss, Dominik ; Wisotzki, Andreas ; Woodward, E. Malcolm S. ; Wu, Jingfeng ; Wu, Yingzhe ; Wuttig, Kathrin ; Wyatt, Neil ; Xiang, Yang ; Xie, Ruifang C. ; Xue, Zichen ; Yoshikawa, Hisayuki ; Zhang, Jing ; Zhang, Pu ; Zhao, Ye ; Zheng, Linjie ; Zheng, Xin-Yuan ; Zieringer, Moritz ; Zimmer, Louise A. ; Ziveri, Patrizia ; Zunino, Patricia ; Zurbrick, Cheryl
    The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 25 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017. This article is part of a special issue entitled: Conway GEOTRACES - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González.
  • Working Paper
    Paths forward for exploring ocean iron fertilization
    (Woods Hole Oceanographic Institution, 2023-10-26) Buesseler, Kenneth O. ; Bianchi, Daniele ; Chai, Fei ; Cullen, Jay T. ; Estapa, Margaret L. ; Hawco, Nicholas J. ; John, Seth G. ; McGillicuddy, Dennis J. ; Nawaz, Sara ; Ramakrishna, Kilaparti ; Siegel, David A. ; Smith, Sarah R. ; Steinberg, Deborah K. ; Turk-Kubo, Kendra A. ; Twining, Benjamin S. ; Webb, Romany ; Wells, Mark L. ; White, Angelicque E. ; Yoon, Joo-Eun
    We need a new way of talking about global warming. UN Secretary General António Guterres underscored this when he said the “era of global boiling” has arrived. Although we have made remarkable progress on a very complex problem over the past thirty years, we have a long way to go before we can keep the global temperature increase to below 2°C relative to the pre-industrial times. Climate models suggest that this next decade is critical if we are to avert the worst consequences of climate change. The world must continue to reduce greenhouse gas emissions, and find ways to adapt and build resilience among vulnerable communities. At the same time, we need to find new ways to remove carbon dioxide from the atmosphere in order to chart a “net negative” emissions pathway. Given their large capacity for carbon storage, the oceans must be included in consideration of our multiple carbon dioxide removal (CDR) options. This report focused on ocean iron fertilization (OIF) for marine CDR. This is by no means a new scientific endeavor. Several members of ExOIS (Exploring Ocean Iron Solutions) have been studying this issue for decades, but the emergence of runaway climate impacts has motivated this group to consider a responsible path forward for marine CDR. That path needs to ensure that future choices are based upon the best science and social considerations required to reduce human suffering and counter economic and ecological losses, while limiting and even reversing the negative impacts that climate change is already having on the ocean and the rest of the planet. Prior studies have confirmed that the addition of small amounts of iron in some parts of the ocean is effective at stimulating phytoplankton growth. Through enhanced photosynthesis, carbon dioxide can not only be removed from the atmosphere but a fraction can also be transferred to durable storage in the deep sea. However, prior studies were not designed to quantify how effective this storage can be, or how wise OIF might be as a marine CDR approach. ExOIS is a consortium that was created in 2022 to consider what OIF studies are needed to answer critical questions about the potential efficiency and ecological impacts of marine CDR (http://oceaniron.org). Owing to concerns surrounding the ethics of marine CDR, ExOIS is organized around a responsible code of conduct that prioritizes activities for the collective benefit of our planet with an emphasis on open and transparent studies that include public engagement. Our goal is to establish open-source conventions for implementing OIF for marine CDR that can be assessed with appropriate monitoring, reporting, and verification (MRV) protocols, going beyond just carbon accounting, to assess ecological and other non-carbon environmental effects (eMRV). As urgent as this is, it will still take 5 to 10 years of intensive work and considerable resources to accomplish this goal. We present here a “Paths Forward’’ report that stems from a week-long workshop held at the Moss Landing Marine Laboratories in May 2023 that was attended by international experts spanning atmospheric, oceanographic, and social sciences as well as legal specialists (see inside back cover). At the workshop, we reviewed prior OIF studies, distilled the lessons learned, and proposed several paths forward over the next decade to lay the foundation for evaluating OIF for marine CDR. Our discussion very quickly resulted in a recommendation for the need to establish multiple “Ocean Iron Observatories’’ where, through observations and modeling, we would be able to assess with a high degree of certainty both the durable removal of atmospheric carbon dioxide—which we term the “centennial tonne”—and the ecological response of the ocean. In a five-year phase I period, we prioritize five major research activities: 1. Next generation field studies: Studies of long-term (durable) carbon storage will need to be longer (year or more) and larger (>10,000 km2) than past experiments, organized around existing tools and models, but with greater reliance on autonomous platforms. While prior studies suggested that ocean systems return to ambient conditions once iron infusion is stopped, this needs to be verified. We suggest that these next field experiments take place in the NE Pacific to assess the processes controlling carbon removal efficiencies, as well as the intended and unintended ecological and geochemical consequences. 2. Regional, global and field study modeling Incorporation of new observations and model intercomparisons are essential to accurately represent how iron cycling processes regulate OIF effects on marine ecosystems and carbon sequestration, to support experimental planning for large-scale MRV, and to guide decision making on marine CDR choices. 3. New forms of iron and delivery mechanisms Rigorous testing and comparison of new forms of iron and their potential delivery mechanisms is needed to optimize phytoplankton growth while minimizing the financial and carbon costs of OIF. Efficiency gains are expected to generate responses closer to those of natural OIF events. 4. Monitoring, reporting, and verification: Advances in observational technologies and platforms are needed to support the development, validation, and maintenance of models required for MRV of large-scale OIF deployment. In addition to tracking carbon storage and efficiency, prioritizing eMRV will be key to developing regulated carbon markets. 5. Governance and stakeholder engagement: Attention to social dimensions, governance, and stakeholder perceptions will be essential from the start, with particular emphasis on expanding the diversity of groups engaged in marine CDR across the globe. This feedback will be a critical component underlying future decisions about whether to proceed, or not, with OIF for marine CDR. Paramount in the plan is the need to move carefully. Our goal is to conduct these five activities in parallel to inform decisions steering the establishment of ocean iron observatories at multiple locations in phase II. When completed, this decadal plan will provide a rich knowledge base to guide decisions about if, when, where, and under what conditions OIF might be responsibly implemented for marine CDR. The consensus of our workshop and this report is that now is the time for actionable studies to begin. Quite simply, we suggest that some form of marine CDR will be essential to slow down and reverse the most severe consequences of our disrupted climate. OIF has the potential to be one of these climate mitigation strategies. We have the opportunity and obligation to invest in the knowledge necessary to ensure that we can make scientifically and ethically sound decisions for the future of our planet.