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Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean
Thesis (MSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613940418084864 |
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| access_status_str | Open Access |
| author | Sitofile, Miranda |
| author2 | Roychoudhury, Alakendra. N. |
| author_browse | Roychoudhury, Alakendra. N. Sitofile, Miranda |
| author_facet | Roychoudhury, Alakendra. N. Sitofile, Miranda |
| author_sort | Sitofile, Miranda |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/134822 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:44:07.837Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/134822 Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean Sitofile, Miranda Roychoudhury, Alakendra. N. Ryan-Keogh, Thomas. J. Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Iron -- Environmental aspects -- Southern Ocean Seawater -- Carbon dioxide content -- Atlantic Ocean Trace elements in water -- Atlantic Ocean Phytoplankton -- Atlantic Provinces Carbon cycle (Biogeochemistry) Ocean-atmosphere interaction -- Atlantic Ocean UCTD Thesis (MSc)--Stellenbosch University, 2025. Sitofile, M. 2025. Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/83587ac3-d5d2-416e-894a-13389405bbe1 ENGLISH ABSTRACT: About one-third of global carbon dioxide uptake occurs in the Southern Ocean and is driven by mechanisms such as the biological carbon pump. The functioning of the biological carbon pump system is regulated in part by the availability of the crucial micronutrient iron, due to its significant role in the functioning of phytoplankton photosynthetic proteins and other metabolic processes. Despite its significance, dissolved iron (dFe) remains under-investigated in the Southern Ocean due to seasonal data limitations, particularly during winter, hindering a comprehensive understanding of its complete seasonal cycle. This study provides the first combined winter and spring data in the Southern Ocean’s south Atlantic sector, from 36.60ºS down to 55.98ºS, collected during the SCALE 2019 scientific voyages. The samples underwent analysis through Inductively Coupled Plasma Mass Spectrometry (ICP-MS), a method known for its precision in measuring trace metals. This analysis allowed the determination of the distribution of dFe in the surface (200 m) and below the surface (200 to 2000 m). This study primarily focused on quantifying physical supply processes driving the supply of dFe into the mixed layer. Results showed varying surface dFe concentrations across the zones, with notably high surface concentrations observed in the Polar frontal zone in both seasons. Winter dFe concentrations along the transect (surface to 2000 m) ranged from 0.05 to 1.30 nmol kg-1, while in spring there was a slightly increased range of 0.08 to 1.58 nmol kg-1. The coupling between Fe and phosphate revealed that Fe was potentially a limiting factor of productivity across the transect in both winter and spring, with Fe* values negative throughout the transect. Winter entrainment was determined to be the primary supply mechanism (>98.96 %), followed by diapycnal diffusion as a secondary supply process (2.33%). Ekman pumping was found to be a negligible supply process, contributing less than 0.13%. This study concludes that winter entrainment drives dFe supply to the mixed layer, which is essential for productivity across the seasonal cycle. By highlighting the role of physical processes in shaping dFe distribution, this study has provided valuable insights into how seasonal variations influence dFe availability in the Southern Ocean. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2026-01-09T10:35:51Z 2026-01-09T10:35:51Z 2025-12 Thesis https://scholar.sun.ac.za/handle/10019.1/134822 Stellenbosch University xv, 93 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Iron -- Environmental aspects -- Southern Ocean Seawater -- Carbon dioxide content -- Atlantic Ocean Trace elements in water -- Atlantic Ocean Phytoplankton -- Atlantic Provinces Carbon cycle (Biogeochemistry) Ocean-atmosphere interaction -- Atlantic Ocean UCTD Sitofile, Miranda Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title | Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title_full | Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title_fullStr | Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title_full_unstemmed | Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title_short | Winter and Spring insights into physical drivers of iron supply to the mixed layer in the South Atlantic sector of the Southern Ocean |
| title_sort | winter and spring insights into physical drivers of iron supply to the mixed layer in the south atlantic sector of the southern ocean |
| topic | Iron -- Environmental aspects -- Southern Ocean Seawater -- Carbon dioxide content -- Atlantic Ocean Trace elements in water -- Atlantic Ocean Phytoplankton -- Atlantic Provinces Carbon cycle (Biogeochemistry) Ocean-atmosphere interaction -- Atlantic Ocean UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/134822 |
| work_keys_str_mv | AT sitofilemiranda winterandspringinsightsintophysicaldriversofironsupplytothemixedlayerinthesouthatlanticsectorofthesouthernocean |