Rare earth elements in the North Atlantic, part II: Partition coefficients

• Published in: Chemical Geology
• Main Authors: Lagarde, Marion, Pham, Viet, Quoc, Lemaitre, Nolwenn, Belhadj, Moustafa, Jeandel, Catherine
• Other Authors: Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institute of Environmental Technology Hanoi (IET), Vietnam Academy of Science and Technology (VAST), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: Rare earth elements; Dissolved particulate exchanges; Partition coefficients; Suspended particle mass; Manganese oxides iron hydroxides; GEOTRACES; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE]Environmental Sciences; North Atlantic
• Online Access: https://hal.univ-brest.fr/hal-04674291; https://hal.univ-brest.fr/hal-04674291/document; https://hal.univ-brest.fr/hal-04674291/file/1-s2.0-S0009254124003784-main.pdf; https://doi.org/10.1016/j.chemgeo.2024.122298

International audience This study presents the first basin scale section of the partition coefficients (Kd) of 14 rare earth elements (REE)along the GEOVIDE (GEOTRACES GA01 cruise) transect, in the subpolar North Atlantic (May–June 2014, R/VPourquoi Pas?). Although Kd data are very scarce in the literature, it is a key parameter of element cyclemodeling, controlling the scavenging efficiency by particles. Because of this lack of data, Kd are generallyadjusted in the models to obtain the best agreement between modeled and observed concentrations. Thisshortcoming likely contributes to make the modeling of the oceanic REE cycles challenging. This is well illus-trated by the difficulty to satisfactorily simulate both Nd concentrations and isotopic compositions.Here, we determined Kd(REE) at 10 stations, calculated from previously published dissolved and particulateREE concentrations, and from suspended particulate matter (SPM) concentrations. The data required for thecalculation of SPM concentrations were obtained in the framework of the GEOVIDE cruise. Kd profiles displayedminimum values at the surface, variations in the upper 400 m, and an increase with depth below 400 m. Theexpression of the ratio of particulate to dissolved REE concentrations as a function of SPM concentrations showedthat manganese oxides (MnO2) were the main driver of REE scavenging, followed by the lithogenic phase andiron hydroxides (Fe(OH)3). Our study also highlighted that REE scavenging preferentially depended on therelative proportion of these three phases rather than on their absolute concentrations. These conclusions wereevaluated by a Pearson correlation test, with correlation coefficients of 0.83, 0.84, and 0.75 between Kd(Nd) andthe MnO2, lithogenic, and Fe(OH)3 fractions, respectively.Finally, we proposed two Kd(Nd) parameterizations as a function of the particulate phase fractions. The firstparameterization included MnO2 and Fe(OH)3, phases that are currently not represented in Nd cycle models, andshowed a good agreement between ...