Mechanistic Constraints on the Drivers of Southern Ocean Meridional Iron Distributions Between Tasmania and Antarctica

• Published in: Global Biogeochemical Cycles
• Main Authors: Traill, Christopher D., Pardo, Paula C., Rohr, Tyler, van der Merwe, Pier, Townsend, Ashley T., Latour, Pauline, Gault‐Ringold, Melanie, Wuttig, Kathin, Corkill, Matthew, Holmes, Thomas M., Warner, Mark J., Shadwick, Elizabeth, Bowie, Andrew R.
• Other Authors: Australian Research Council, Antarctic Climate and Ecosystems Cooperative Research Centre (Australia), University of Tasmania, Council of Australian University Librarians
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2024
• Subjects: Antarc*; Antarctic; Antarctica; Southern Ocean
• Online Access: http://hdl.handle.net/10261/353107; https://doi.org/10.1029/2023GB007856

20 pages, 4 figures, 1 table.-- This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License While modeling efforts have furthered our understanding of marine iron biogeochemistry and its influence on carbon sequestration, observations of dissolved iron (dFe) and its relationship to physical, chemical and biological processes in the ocean are needed to both validate and inform model parameterization. Where iron comes from, how it is transported and recycled, and where iron removal takes place are critical mechanisms that need to be understood to assess the relationship between iron availability and primary production. To this end, hydrographic and trace metal observations across the GO-SHIP section SR3, south of Tasmania, Australia, have been analyzed in tandem with the novel application of an optimum multiparameter analysis. From the trace-metal distribution south of Australia, key differences in the drivers of dFe between oceanographic zones of the Southern Ocean were identified. In the subtropical zone, sources of dFe were attributed to waters advected off the continental shelf, and to recirculated modified mode and intermediate water-masses of the Tasman Outflow. In the subantarctic zone, the seasonal replenishment of dFe in Antarctic surface and mode waters appears to be sustained by iron recycling in the underlying mode and intermediate waters. In the southern zone, the dFe distribution is likely driven by dissolution and scavenging by high concentrations of particles along the Antarctic continental shelf and slope entrained in high salinity shelf water. This approach to trace metal analysis may prove useful in future transects for identifying key mechanisms driving marine dissolved trace metal distributions This work was funded through receipt of Australian Research Council Grants FT130100037 (to ARB) and LE0989539 (to ATT and ARB for analysis) and by the Antarctic Climate & Ecosystems Cooperative Research Centre (ACE CRC), the Antarctic Science ...