230Th, 231Pa, and 10Be in particle size fractions of an opal-rich sediment of the Atlantic Southern Ocean ...

• Main Authors: Kretschmer, Sven, Geibert, Walter, Rutgers van der Loeff, Michiel M, Schnabel, Christoph, Xu, Sheng, Mollenhauer, Gesine
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2011
• Subjects: Gravity corer Kiel type; ANT-VIII/3; Polarstern; Marine Geochemistry @ AWI AWI_MarGeoChem; Paleoenvironmental Reconstructions from Marine Sediments @ AWI AWI_Paleo; Southern Ocean
• Online Access: https://dx.doi.org/10.1594/pangaea.759976; https://doi.pangaea.de/10.1594/PANGAEA.759976

This study centers on the question: How sensitive are 231Pa/230Th and 10Be/230Th to sediment composition and redistribution? The natural radionuclides 231Pa, 230Th and 10Be recorded in deep sea sediments are tracers for water mass advection and particle fluxes. We investigate the influence of oceanic particle composition on the element adsorption in order to improve our understanding of sedimentary isotope records. We present new data on particle size specific 231Pa and 10Be concentrations. An additional separation step, based on settling velocities, led to the isolation of a very opal-rich phase. We find that opal-rich particles contain the highest 231Pa and 10Be concentrations, and higher 231Pa/230Th and 10Be/230Th isotope ratios than opal-poor particles. The fractionation relative to 230Th induced by the adsorption to opal-rich particles is more pronounced for 231Pa than for 10Be. We conclude that bulk 231Pa/230Th in Southern Ocean sediments is most suitable as a proxy for past opal fluxes. The comparison ... : Supplement to: Kretschmer, Sven; Geibert, Walter; Rutgers van der Loeff, Michiel M; Schnabel, Christoph; Xu, Sheng; Mollenhauer, Gesine (2011): Fractionation of **230Th, **231Pa, and **10Be induced by particle size and composition within an opal-rich sediment of the Atlantic Southern Ocean. Geochimica et Cosmochimica Acta, 75(22), 6971-6987 ...