Dust variability and provenance in the Pacific and Atlantic sectors of the Southern Ocean

• Main Author: Wengler, Marc
• Other Authors: Tiedemann, Ralf, Lamy, Frank, Mollenhauer, Gesine
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2018
• Subjects: South Pacific; Modern dust provenance; Lithogenic fluxes; Rare earth elements; Radiogenic isotopes; Southern Ocean; Southern Westerly Winds; Eolian dust; Glacial - Interglacial dust variability; 550; 550 Earth sciences and geology; ddc:550; Pacific
• Online Access: https://media.suub.uni-bremen.de/handle/elib/1495; https://nbn-resolving.org/urn:nbn:de:gbv:46-00106737-15

The effect of dust on the global climate results from processes in the atmosphere and in the ocean. On the one hand, dust in the atmosphere scatters or absorbs incoming sunlight (a direct influence on climate) or modifies cloud properties (an indirect influence on climate). On the other hand, dust can stimulate the marine productivity by supplying iron to the ocean (iron fertilization). Increased dust fluxes, especially during glacial periods, may have enhanced the marine productivity in the Southern Ocean, which was likely responsible for an atmospheric CO2 reduction of 40 ppmv. Subsequently, the Southern Ocean is a crucial component of the global climate system. Analyzing marine dust records deposited downwind of the major Southern Hemisphere dust source areas provides valuable information on paleoclimate changes in source areas characteristics (e.g. aridity, precipitation, wind) and within the dust transporting winds. Based on these analyses, this dissertation aims to contribute to a better understanding of paleoclimate changes inferred from the dust variability of marine dust records from the Southern Ocean. To achieve this goal, four manuscripts are presented in chapters 3, 4, 5 and 6, which each utilizes different methodical approaches. A comprehensive set of sediment surface samples and sediment cores from the Pacific and Atlantic sectors of the Southern Ocean was used to conduct dust provenance, grain size and biomarker analyses. Manuscript one (chapter 3) presents the first combined lithogenic flux and dust provenance analysis extracted from sediment surface samples from the Pacific sector of the Southern Ocean, which allows to better understand Holocene dust variability. The lowest lithogenic fluxes detected in open ocean surface sediments are interpreted as solely derived from atmospheric dust. The provenance analysis reveals that sources in central and southeast Australia dominate the dust supply to the Pacific sector of the Southern Ocean during the Holocene. The second manuscript (chapter 4) aims ...