230Th and 231Pa – tracers for particle fluxes and deep water circulation in the Central Arctic Ocean

• Main Author: Valk, Ole
• Other Authors: Kasten, Sabine, Rutgers van der Loeff, Michiel, Frank, Martin
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2021
• Subjects: Arctic Ocean; Trace Elements; 550; 550 Earth sciences and geology; ddc:550; Arctic; Climate change; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/5451; https://doi.org/10.26092/elib/1184; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib54510

The currently ongoing climate change can be ascribed without exaggerating as one the most important topics and threats for humanity. Understanding its mechanisms and consequences is an important step to target and manage arising problems, which accompany a rapidly warming climate. The oceans play a crucial role in the Earth’s climate controlling and response mechanism. Its physical and biological carbon pump systems are crucial regulators for the atmospheric CO2 content. Biological primary production is an important part of the Oceans CO2 uptake capability. Some trace elements are important (micro-) nutrients in oceanic primary production. Therefore it is important to investigate and understand the reaction of those elements to changing environmental conditions. Particle fluxes and ocean circulation contribute to their distribution in the water column. 230Th and 231Pa are suitable tracers for both particle fluxes and deep water circulation. Their well-known sources and production ratio, as well as their fractionation by particle fluxes and deep water circulation, enables their use as tracers. Their water column distribution serves as an indicator for recent environmental changes, while their sedimentary 231Pa/230Th activity ratio is used as a paleoceanographic tool. Therefore 230Th and 231Pa are standard parameters of GEOTRACES, an international programme with the goal to improve understanding of the cycling of trace elements and their isotopes in the Ocean. Different areas of the World’s Ocean react in different velocities and intensities to climate change. The Arctic Ocean is the most sensitive one to climate change. Climate change related consequences are already visible, e.g. the retreat and thinning of sea ice. Other consequences, like increasing particle fluxes and changing particle composition, as well as potentially changing circulation patterns and ventilation times are less obvious. It is expected that climate change will cause significant changes on the Arctic Oceans’ primary production and particle ...