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The GEOTRACES Intermediate Data Product 2017
Schlitzer, Reiner Anderson, Robert F. Dodas, Elena Masferrer Lohan, Maeve Geibere, Walter Tagliabue, Alessandro Bowie, Andrew 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 de Baar, Hein J. Baars, Oliver Baker, Alex R. Bakker, Karel Basak, Chandranath Baskaran, Mark Bates, Nicholas R. Bauch, Dorothea van Beek, Pieter Behrens, Melanie K. Black, Erin 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-Juergen Brzezinski, Mark Buck, Clifton S. Buck, Kristen N. Buesseler, Ken Bull, Abby Butler, Edward Cai, Pinghe Camara 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 Conway, Tim M. Cossa, Daniel Croot, Peter 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 Fahrbach, Eberhard Fitzsimmons, Jessica N. Flegal, A. Russell Fleisher, Martin Q. van de Flierdt, Tina Frank, Martin Friedrich, Jana Fripiat, Francois Froellje, 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 M. Goldstein, Steven L. Gonzalez, Santiago R. Grissom, Karen Hammerschmidt, Chad Hartman, Alison Hassler, Christel S. Hathorne, Ed C. Hatta, Mariko Hawco, Nicholas Hayes, Christopher T. Heimburger, Lars-Eric Helgoe, Josh Heller, Maija 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 C. 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, Frederic A. C. Le Roy, Emilie Lechtenfeld, Oliver J. Lee, Jong-Mi Lherminier, Pascale Little, Susan Lopez-Lora, Mercedes Lu, Yanbin Masque, Pere Mawji, Edward Mcclain, Charles R. Measures, Christopher Mehic, Sanjin Menzel Barraqueta, Jan-Lukas van der Merwe, Pier 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 Obata, Hajime Ober, Sven Ohnemus, Daniel C. van Ooijen, Jan O'Sullivan, Jeanette Owens, Stephanie Pahnke, Katharina Paul, Maxence Pavia, Frank Pena, Leopoldo D. Petersh, Brian Planchon, Frederic Planquette, Helene Pradoux, Catherine Puigcorbe, Viena Quay, Paul Queroue, Fabien Radic, Amandine Rauschenberg, S. Rehkamper, Mark Rember, Robert Remenyi, Tomas Resing, Joseph A. Rickli, Joerg Rigaud, Sylvain Rijkenberg, Micha J. A. Rintoul, Stephen Robinson, Laura F. Roca-Marti, Montserrat Rodellas, Valenti Roeske, Tobias Rolison, John M. Rosenberg, Mark Roshan, Saeed van der Loaff, Michiel M. Rutgers Ryabenko, Evgenia Saito, Mak A. Salt, Lesley A. Sanial, Virginie Sarthou, Geraldine Schallenberg, Christina Schauer, Ursula Scher, Howie Schlosser, Christian Schnetger, Bernhard Scott, Peter Sedwick, Peter N. Semiletov, Igor Shelley, Rachel Sherrell, Robert M. Shiller, Alan M. Sigman, Daniel M. Singh, Sunil Kumar Slagter, Hans A. Slater, Emma Smethie, William M. Snaith, Helen Sohrin, Yoshiki Sohst, Bettina 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, CherylThe 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-s 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. Gonzalez.
The biogeochemistry of cobalt in the Mediterranean Sea
Dulaquais, Gabriel Planquette, Hélène L\"Helguen, Stéphane Rijkenberg, Micha J. A. Boye, MarieThe soluble (sCo < 0.02 µm), dissolved (DCo < 0.2 µm), colloidal (cCo, as DCo minus sCo), and the particulate (pCo > 0.2 µm) fractions of cobalt were investigated along the GEOTRACES-A04 section. Our results show that sCo was the predominant form (90%) of the DCo in the Mediterranean Sea and that cCo and pCo generally followed the same distribution, suggesting a biogeochemical link between these two fractions. In the Mediterranean Sea, DCo displayed an overall scavenged-like profile in the different sub-basins, with high concentrations (up to 350 pM) in surface and quasi-uniformed low concentrations of DCo (~45 pM) in the deep sea. However, the decoupling between the surface and the deep reservoirs suggested that the transfer of Co from dissolved to particulate pools during the sink of particles may not be the only process governing DCo distribution. High-surface Co inputs, stabilization of DCo in a soluble form, and the extremely high regeneration rate of biogenic pCo all lead to the accumulation of DCo in surface. Conversely, low pCo export from the surface waters, low remineralization of biogenic pCo, and slow but efficient removal of DCo by scavenging including colloid aggregation into particles prevented its accumulation in the intermediate and deep sea. Moreover, Mediterranean circulation prevented the exchanges between the DCo-rich surface and the DCo-poor deep layers enhancing the scavenged-like profile of DCo. Finally, tentative DCo budgets were balanced at basin scale and showed the strong imprint of the surface inputs at Gibraltar Strait on the Mediterranean cobalt biogeochemistry.
Contrasting biogeochemical cycles of cobalt in the surface western Atlantic Ocean
Dulaquais, Gabriel Boye, Marie Middag, Rob Owens, Stephanis Puigcorbe, Viena Buesseler, Ken Masqué, Pere de Baar, Hein J. W. Carton, XavierDissolved cobalt (DCo; <0.2 mu m; 14 to 93 pM) and the apparent particulate cobalt (PCo; >0.2 mu m; <1 to 15 pM) were determined in the upper water column (<1000m) of the western Atlantic Ocean along the GEOTRACES-A02 section (64 degrees N to 50 degrees S). The lowest DCo concentrations, typical of a nutrient-type distribution were observed in surface waters of the subtropical domains. Strong linear relationships between DCo and phosphate (P) as well as meridional gradients of decreasing DCo from high latitudes were characterized and both linked to the Co biological requirement. External sources such as the Amazon and the atmospheric deposition were found to contribute significantly (>10%) to the DCo stock of the mixed layer in the equatorial and north subtropical domains. Biotic and abiotic processes as well as the physical terms involved in the biogeochemical cycle of Co were defined and estimated. This allowed establishing the first global budget of DCo for the upper 100m in the western Atlantic. The biological DCo uptake flux was the dominant sink along the section, as reflected by the overall nutrient-type behavior of DCo. The regeneration varied widely within the different biogeochemical domains, accounting for 10% of the DCo-uptake rate in the subarctic gyre and for up to 85% in southern subtropical domain. These findings demonstrated that the regeneration is likely the prevailing source of DCo in the surface waters of the western Atlantic, except in the subpolar domains where physically driven sources can sustain the DCo biological requirement.
Determination of the copper isotope composition of seawater revisited:A case study from the Mediterranean Sea
Baconnais, Isabelle Rouxel, Olivier Dulaquais, Gabriel Boye, MarieA new technique for the determination of dissolved copper isotope composition (delta Cu-65) of seawater was applied to examine copper sources and internal cycling in the Mediterranean Sea along the GEOTRACES GA04N transect. A succession of chelating resin with nitrilotriacetic acid functional groups and strong base anion exchange resin, together with optimization of the multi-collector inductively coupled plasma mass spectrometry set-up allowed to isolate copper from seawater matrix and to measure the Cu-65/Cu-63 ratios in seawater with an external precision of 0.06% (2 s.d.). This method was first applied for inter-comparison measurements to surface and deep waters sampled at the Bermuda Atlantic Time-Series station (BATS) in the North Atlantic Ocean during the GEOTRACES Intercalibration Cruise 1. Disparities in delta Cu-65 reported here and in the literature over these samples showed a need to investigate whether a new inter-comparison sample should be decided upon, or whether the use of UV-oxidation can also affect the measurement of delta Cu-65. We also measured total dissolved Cu concentration ([dCu](T)) and delta Cu-65 for 12 stations in the Mediterranean Sea. The delta Cu-65 distribution showed significant variations in the euphotic zone, at the Chl a maximum and at bottom depths. Copper isotope ratios ranged from +0.21% to +0.76% (+/- 0.06%, 2 s.d.), yielding an average of + 0.51% (+/- 0.20%, 2 s.d.; n =3D 96) for the Mediterranean Sea. A strong zonation between natural aerosol deposition to the South and anthropogenic aerosol deposition to the North was seen in the sample set (Dulaquais et al. 2017; Gerringa et al. 2017; Rolison et al. 2015). Natural dust deposits seemed to draw delta Cu-65 toward lower values and deeper in the euphotic zone whereas the impact of anthropogenic aerosols seemed restricted to an increase in [dCu](T). At the Chl a maximum, delta Cu-65 showed significant increase which we attributed to scavenging on and/or uptake by phytoplankton. The isotope signature of Cu sources to the Mediterranean Sea was also investigated and we inferred a significant source of isotopically heavy Cu in the Gibraltar area, potentially originating from a release of Cu sulfide leached in the mining area of Southern Spain (i.e. Iberian Pyrite Belt) in rivers and transported to the Mediterranean Sea in surface by seasonal water mass circulation. Conversely, marine sediments appear to be a source of isotopically-light Cu to deep waters. This study provides new hints on the use of copper isotopes to study sources and sinks of Cu in seawater. This article is part of a special issue entitled: "Cycles of trace elements and isotopes in the ocean - GEOTRACES and beyond" - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. Gonzalez.
Measuring dissolved organic matter in estuarine and marine waters:size-exclusion chromatography with various detection methods
Dulaquais, Gabriel Breitenstein, Johann Waeles, Matthieu Marsac, Remi Riso, RicardoWe studied the performance and limitations of size-exclusion chromatography with organic carbon, ultraviolet and organic nitrogen detectors (SEC-OCD-UVD-OND) for characterising dissolved organic matter (DOM) in estuarine and marine waters. We identified a strong salt effect on dissolved organic carbon (DOC) determination; however, calibration gave good results at salinity levels close to those of the sample analysed (Delta S +/- 2 psu (practical salinity units)), with limited matrix effects, enabling an accurate measurement of DOC, as demonstrated by an intercalibration exercise. The repeatability, reproducibility and limit of detection (3 ppb for both carbon and nitrogen) for the three detectors demonstrated the robustness of the method for a wide range of natural waters, including carbon-rich freshwaters and deep seawaters with low carbon content (6000 ppb-C to 300 ppb-C). Deeper analysis of the SEC demonstrated that proteins and polysaccharides are partly fractionated within the column, and that terrestrial humic substances, isolated on a XAD-8 resin, can also be eluted in both fractions associated with biopolymers and low-molecular- weight neutrals. Application of the method to the study of DOM along a macrotidal estuary that was influenced by agricultural activities revealed significant changes in its composition despite a conservative DOC distribution. Distinct origins and qualities of high-molecular-weight (> 500 kDa) organic compounds were identified for riverine and marine end-members. A new diagram to track changes in DOM lability is proposed to complete the humic-substances diagram.
The Biogeochemistry of Electroactive Humic Substances and Its Connection to Iron Chemistry in the North East Atlantic and the Western Mediterranean Sea
Dulaquais, Gabriel Waeles, Matthieu Gerringa, Loes J. A. Middag, Rob Rijkenberg, Micha J. A. Riso, RicardoWe present the zonal distribution of electroactive humic-like substances (eHS) along a section from Offshore Portugal in the North East Atlantic to the Sicily Channel in the Mediterranean Sea. The concentrations were normalized to Suwannee River Fulvic Acid and ranged from 11g/L to 81g/L. The vertical distributions were typical of those previously reported for dissolved organic carbon in the Mediterranean Sea. High eHS concentrations were measured in surface water and concentrations decreased with depth before increasing again toward benthic maxima measured at some stations. We estimate that eHS represented a relatively small fraction of the natural organic matter in the Mediterranean Sea (2-5%) but considering their important role in the complexation and the solubility of key trace elements (e.g., iron and copper), the eHS cycle could influence the entire biogeochemistry of these marine systems. We identified key processes controlling the concentration of eHS. While biologically mediated production was the major source of eHS, riverine and rain inputs as well as sediment release were also likely external sources. Low eHS concentrations at subsurface depths pointed to photodegradation as a possible sink of eHS, but degradation by heterotrophic bacteria seemed to be the main sink in the deep sea. Finally, we found a positive correlation between dissolved iron and eHS concentrations. Estimation of eHS contribution to iron binding ligand concentrations indicates the complexation of iron by eHS in the Mediterranean Sea. These observations suggest links between the cycles of eHS and iron in the Mediterranean Sea.