Thorium isotopes in the water column in Nansen Basin during POLARSTERN cruises PS70 (ARK-XXII/2) in 2007 and PS94 (ARK-XXIX/3) in 2015

• Main Authors: Valk, Ole, Rutgers van der Loeff, Michiel M, Geibert, Walter
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: AWI_MarGeoChem; GEOTRACES; Global marine biogeochemical cycles of trace elements and their isotopes; Marine Geochemistry @ AWI; Arctic; Arctic Ocean; Nansen Basin
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.893871; https://doi.org/10.1594/PANGAEA.893871

In this study we present dissolved and particulate 230Th and 232Th results, as well as particulate 234Th data, obtained as part of the GEOTRACES central Arctic Ocean sections GN04 (2015) and IPY11 (2007). Samples were analyzed following GEOTRACES methods, and compared to previous results from 1991. We observe significant decreases in 230Th concentrations in the deep waters of the Nansen Basin. We ascribe this non-steady state removal process to a variable release and scavenging of trace metals near an ultra-slow spreading ridge. This finding demonstrates that hydrothermal scavenging in the deep-sea may vary on annual time scales and highlights the importance of repeated GEOTRACES sections.