Cadmium in the waters off South Morocco: Nature of particles hosting Cd and insights into the mechanisms fractionating Cd from phosphate

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Waeles, Matthieu, Planquette, Hélène, Afandi, Imane, Delebecque, Nina, Bouthir, Fatimazohra, Donval, Anne, Shelley, Rachel U., Auger, Pierre-Amaël, Riso, Ricardo, D., Tito de Morais, Luis
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Pontificia Universidad Católica de Valparaíso (PUCV), Institut de Recherche pour le Développement (IRD), ANR-11-CEPL-0005,ÉPURE,Éléments trace métalliques Perturbations climatiques Upwelling et REssources(2011), ANR-12-PDOC-0025,BITMAP,Biodisponibilité du fer et des métaux traces dans les particules marines(2012), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; North Atlantic
• Online Access: https://hal.science/hal-01482790; https://hal.science/hal-01482790/document; https://hal.science/hal-01482790/file/JGR%20Oceans%20-%202016%20-%20Waeles%20-%20Cadmium%20in%20the%20waters%20off%20South%20Morocco%20Nature%20of%20particles%20hosting%20Cd%20and%20insights%20into%20the.pdf; https://doi.org/10.1002/2016JC011688

International audience In this study we report the distributions of total dissolvable cadmium and particulate cadmium from 27 stations in southern Moroccan coastal waters (22-30°N) which is part of the North-West African upwelling system. These distributions were predominantly controlled by upwelling of the North Atlantic Central Waters (NACW) and uptake by primary production. Atmospheric inputs and phosphogypsum slurry inputs from the phosphate industry at Jorf Lasfar (33°N), recently estimated as an important source of dissolved cadmium (240 tCd year−1), are at best of minor importance for the studied waters. Our study provides new insights into the mechanisms fractionating cadmium from phosphate. In the upper 30 m, the anomalies observed in terms of Cd:P ratios in both the particulate and total dissolvable fractions were related to an overall preferential uptake of phosphate. We show that the type of phytoplanktonic assemblage (diatoms vs dinoflagellates) is also a determinant of the fractionation intensity. In sub-surface waters (30-60 m), a clear preferential release of P (vs Cd) was observed indicating that remineralization in oxygen minimum zones is a key process in sequestering Cd.