South Pacific GEOTRACES Cruise No. SO289, 18 February 2022 – 08 April 2022, Valparaiso (Chile) – Noumea (New Caledonia), GEOTRACES GP21

• Main Authors: Achterberg, Eric P., Steiner, Zvi, Galley, Christopher G.
• Format: Report
• Language: English
• Published: Gutachterpanel 2022
• Subjects: Austral; Maipo; Pacific; Southern Ocean
• Online Access: https://oceanrep.geomar.de/id/eprint/58239/; https://oceanrep.geomar.de/id/eprint/58239/1/awi_600958138d969d5074d50216e6d6cf01803adf1f.pdf; https://doi.org/10.48433/cr_so289

Research cruise SO289 with FS Sonne was sailed in austral autumn of 2022 in the South Pacific Ocean (SPO) from Valparaiso (Chile) to Noumea (New Caledonia), with a focus on trace element biogeochemistry and chemical oceanography but also including physical and biological oceanographic components. The research topic of the cruise was to determine in detail the distributions, sources and sinks of trace elements and their isotopes (TEIs) in the water column along a zonal section in one of the least studied ocean regions on earth. Our aim was to investigate the biogeochemical cycling of TEIs, and their interactions with surface ocean productivity and the carbon and nitrogen cycles (incl. N2 fixation) given that some TEIs act as micronutrients. The findings will have global significance for understanding the chemical environment in which ecosystems operate. The supply pathways of TEIs to the SPO from ocean boundaries including the atmosphere (Australian dust), continents (mainly Maipo River), sediments (on continental shelves/slopes), and ocean crust (hydrothermalism) were investigated. The TEI transport within water masses was determined with a focus on the southward flow of hydrothermally derived TEIs towards the Southern Ocean but also the deep inflow of Southern Ocean waters in the western SPO. The TEI transport assessment along the cruise track will allow a more reliable use of some TEIs as paleo-circulation proxies. The cruise will officially be part of the international GEOTRACES program.