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Determining the source and distribution of atmospheric mercury over the Southern Ocean
Thesis (MSc)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613888860651520 |
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| access_status_str | Open Access |
| author | Mugabe, Victor Farai |
| author2 | Fietz, Susanne |
| author_browse | Fietz, Susanne Mugabe, Victor Farai |
| author_facet | Fietz, Susanne Mugabe, Victor Farai |
| author_sort | Mugabe, Victor Farai |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/134726 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:43:18.087Z |
| 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:10019.1/134726 Determining the source and distribution of atmospheric mercury over the Southern Ocean Mugabe, Victor Farai Fietz, Susanne Angot, Helene Martin, Lynwill Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Mercury -- Environmental aspects -- South Atlantic Ocean Atmospheric chemistry -- South Atlantic Ocean Ocean-atmosphere interaction -- Mathematical models Biogeochemical cycles -- Seasonal variations Mercury -- Measurement UCTD Thesis (MSc)--Stellenbosch University, 2025. Mugabe, V. F. 2025. Determining the Source and Distribution of Atmospheric Mercury over the Southern Ocean. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/583b37d3-9e1c-48d2-bba8-41e045c41e40 ENGLISH ABSTRACT: The role of the South Atlantic as a source or sink in the global atmospheric mercury cycle remains understudied. Here we present the concentrations of atmospheric mercury over the South Atlantic Ocean, an atmospheric mercury data scarce region. Continuous measurements of atmospheric mercury were conducted using a Tekran 2537X instrument during the Southern Ocean Seasonal Cycle Experiment (SCALE) cruise in 2022 from 13 – 31 July (austral winter) between Cape Point and the Antarctic Ocean ice edge. We report on mean gaseous elemental mercury concentrations in a global context and discuss specific peak and depletion events during the southward and return voyages. The mean concentrations during the southward and return voyages were 1.21 ± 0.23 ng/m3 and 1.22 ± 0.09 ng/m3 respectively. The concentrations over most of the transect ranged from 1.10 – 1.40 ng/m3. During the southward voyage, we observed a peak in atmospheric mercury concentrations at 40.40oS that lasted 7 hours reaching 1.87 ng/m3. We furthermore observed three depletion events (as low as 0.66 ng/m3) close to the sea ice edge. We suggest that these depletion events were caused through mixing of air masses that carried a typical background concentration over the ocean with air masses that carried an Antarctic atmospheric mercury depletion event (AMDE) signal leading to a depleted signal over the ocean. To better constrain the environmental drivers that may have affected the atmospheric mercury concentrations during the voyages, air mass trajectories were modelled, wind directions assessed, and environmental conditions investigated. 168 hours long back trajectories were generated using the HYSPLIT model accessed via the NOAA Air Resources Laboratory READY (Real time Environmental Applications and Display sYstem) website. The back trajectories indicated that the air mass source regions throughout both northward and southward voyages were all oceanic with a few back trajectories indicating southern South America as a terrestrial source region. The mean atmospheric mercury concentrations in the southward and return voyages were not significantly different (p > 0.05) despite higher intensity of solar radiation during the return trip than the southward voyage. This eliminated solar radiation as a control on oceanic mercury degassing and ultimately atmospheric mercury variation along the transect. The highest atmospheric mercury concentrations during the whole cruise were recorded during westerly winds and the lowest were recorded during southerly winds. Overall, our results suggest that the Southern Ocean acts more as a sink rather than a source of atmospheric mercury. We further compare South Atlantic atmospheric mercury concentrations to concentrations recorded at Cape Point, South Africa, during the same period. Air masses at Cape Point and along the transect had been mostly oceanic and indicated similar concentration means of 1.24 ± 0.40 ng/m3 and 1.22 ± 0.18 ng/m3 respectively. Our findings will assist policy makers in monitoring the influence of anthropogenic mercury releases on background concentrations. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2026-01-05T12:28:59Z 2026-01-05T12:28:59Z 2025-12 Thesis https://scholar.sun.ac.za/handle/10019.1/134726 Stellenbosch University ix, 74 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Mercury -- Environmental aspects -- South Atlantic Ocean Atmospheric chemistry -- South Atlantic Ocean Ocean-atmosphere interaction -- Mathematical models Biogeochemical cycles -- Seasonal variations Mercury -- Measurement UCTD Mugabe, Victor Farai Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title | Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title_full | Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title_fullStr | Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title_full_unstemmed | Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title_short | Determining the source and distribution of atmospheric mercury over the Southern Ocean |
| title_sort | determining the source and distribution of atmospheric mercury over the southern ocean |
| topic | Mercury -- Environmental aspects -- South Atlantic Ocean Atmospheric chemistry -- South Atlantic Ocean Ocean-atmosphere interaction -- Mathematical models Biogeochemical cycles -- Seasonal variations Mercury -- Measurement UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/134726 |
| work_keys_str_mv | AT mugabevictorfarai determiningthesourceanddistributionofatmosphericmercuryoverthesouthernocean |