28.10.2019: "Using chromium (Cr) stable isotopes to trace biogenic particle flux in the marine environment"

16:00 Uhr  Gr. Konferenzraum GEOMAR Gebäude 8, Raum 101, Wischhofstr. 1-3

Abstract

Variations in stable chromium isotopes (δ⁵³Cr) may serve as a useful tool for understanding biological and physical processes in the modern and past oceans. For example, solubility changes and stable isotope fractionation associated with Cr redox transformations have led to the use of Cr for inferring paleoredox state of seawater. Additionally, recent data showing the scavenging of dissolved Cr onto phytoplankton cells suggests that δ⁵³Cr in marine sediments may yield constraints on changes in the strength of the marine biological carbon pump both today and in the past. To help assess δ⁵³Cr as a productivity tracer and better understand the yet poorly constrained marine Cr cycle, samples for dissolved Cr concentration, redox speciation and δ⁵³Cr were collected from contrasted biogeochemical environments. These samples, collected across strong gradients in macro- and micronutrient concentrations and in primary productivity, provide insights into the relationship between Cr concentrations, δ⁵³Cr and primary production in varying oceanographic regimes and help determine the potential of the proxy in modern and paleoceanographic settings. Additionally, the results add significantly to the global body of δ⁵³Cr data and help to further a mechanistic understanding of Cr cycling in the global ocean.

Kontakt: Dr. Marcus Gutjahr