SONNE SO289

The research cruise SO289 will be conducted with RV SONNE in austral summer of 2022 in the South Pacific Ocean (SPO) from Valparaiso (Chile) to Auckland (New Zealand), with a focus on trace element biogeochemistry and chemical oceanography but also including physical and biological oceanographic components. The research topic of the cruise is 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. We aim 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) will be investigated. The TEI transport within water masses will be 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 also allow a more reliable use of some TEIs as paleo circulation proxies. The cruise is officially part of the international GEOTRACES program.