210Po and 210Pb distribution,dissolved-particulate exchangerates, and particulate export along the North Atlantic US GEOTRACES GA03 section

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Rigaud, Sylvain, Stewart, Gillian, Baskaran, Mark, Marsan, D, Church, Thomas
• Other Authors: Laboratoire de Géochimie Isotopique Environnementale (GIS) / Université de Nîmes (GIS), Université de Nîmes (UNIMES)-Centre National de la Recherche Scientifique (CNRS), School of Marine Science and Policy, University of Delaware Newark, School of Earth and Environmental Sciences Queens New York, Queens College New York, City University of New York New York (CUNY)-City University of New York New York (CUNY), Department of Geology, Wayne State University Detroit
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: North AtlanticOcean; 210Pb; Hydrothermal plume; Benthic nepheloid layer; GEOTRACES; 210Po; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-01494618; https://hal.archives-ouvertes.fr/hal-01494618/document; https://hal.archives-ouvertes.fr/hal-01494618/file/Rigaud%20et%20al_2015.pdf; https://doi.org/10.1016/j.dsr2.2014.11.003

International audience North Atlantic Ocean Hydrothermal plume Benthic nepheloid layer GEOTRACES a b s t r a c t Vertical profiles of 210 Po and 210 Pb in the water column were measured in the dissolved phase (o0.45 mm), and small (0.8–51 mm) and large (4 51 mm) particles at seven stations along the US GEOTRACES North Atlantic Zonal Transect (GA03). Mass balance calculations were employed to assess nuclide exchange rates at the dissolved-small particle interface and between small and large particles, and to quantify export with settling large particles. In the surface ocean, 210 Po scavenging is linearly correlated with the concentration of particulate organic carbon (POC) in large particles, supporting the role of biogenic particle in 210 Po bioaccumulation and export. In stations near the coast, this link is more complex due to the variable source of biogenic material and temporal changes in the surface biogeochemical and physical conditions. At depth, 210 Po exhibits significant widespread deficit with respect to 210 Pb that could in part be attributed to in situ 210 Po scavenging and may be related to surface biological productivity. As previously reported the 210 Pb scavenging rates in the surface ocean were higher at ocean margins. At depth, 210 Pb scavenging increases with depth and eastward due to the increase of adsorption sites available in the benthic layers and to a regional contribution of benthic 210 Pb scavenging and/or particle flux, respectively. The benthic nepheloid layer (BNL) and the Hydrothermal TAG plume distinctly enhance 210 Pb scavenging due to increased surface adsorption in association with resuspended or freshly formed particles. In contrast, 210 Po is not seen to be significantly scavenged in these environments due to its relatively short half-life and the long residence time of particles.