The Influence of Particle Size, Composition, and Transport on the Distribution of 230Thxs, 231Paxs, and 10Be in Marine Sediments
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Other Titles: | Der Einfluss von Korngrößenverteilung, Partikelzusammensetzung und Sedimenttransport auf die Verteilung von 230Thxs, 231Paxs und 10Be in Meeressedimenten | Authors: | Kretschmer, Sven | Supervisor: | Mollenhauer, Gesine | 1. Expert: | Mollenhauer, Gesine | Experts: | Schlüter, Michael | Abstract: | The study focuses on the grain-size dependent distribution of particle-reactive, natural radionuclides (230Th, 231Pa, 10Be) in marine sediments from the Southern Ocean, the South East Atlantic, and the Equatorial Pacific. Particle-size specific isotope analyses show that a large amount (53-89 %) of the total 230Th is concentrated in clay-size material. It is discussed to what extent a lateral transport of fine particles could generate a biasing to particle flux calculations based on 230Th. In the Southern Ocean sediment the distribution of 231Pa and 10Be strongly depends on the concentration of biogenic silica of particles. 231Pa/230Th and 10Be/230Th in opal-rich particles largely exceed their production ratio in seawater. This supports the application of bulk 231Pa/230Th as a proxy for past opal fluxes to Southern Ocean sediments. The study of compound-specific 231Pa/230Th and 10Be/230Th, as conducted here, allows a more detailed picture of the origin of the isotopic signatures. |
Keywords: | protactinium; thorium; beryllium; 231Pa; 230Th; 10Be; particle flux; particle tracer; biogenic opal; grain size distribution; sediment transport; focusing; winnowing | Issue Date: | 5-Nov-2010 | Type: | Dissertation | Secondary publication: | no | URN: | urn:nbn:de:gbv:46-00101745-16 | Institution: | Universität Bremen | Faculty: | Fachbereich 05: Geowissenschaften (FB 05) |
Appears in Collections: | Dissertationen |
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