Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector
Thesis (MSc)--Stellenbosch University, 2017.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2017
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614072173756416 |
|---|---|
| access_status_str | Open Access |
| author | Loock, Jean Christian |
| author2 | Roychoudhury, Alakendra N. |
| author_browse | Loock, Jean Christian Roychoudhury, Alakendra N. |
| author_facet | Roychoudhury, Alakendra N. Loock, Jean Christian |
| author_sort | Loock, Jean Christian |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2017. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/100925 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:13.197Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/100925 The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector Loock, Jean Christian Roychoudhury, Alakendra N. Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD Thesis (MSc)--Stellenbosch University, 2017. ENGLISH ABSTRACT: The biogeochemical cycling of the bio-active dissolved trace metals cadmium (DCd) and cobalt (DCo), are reported on a meridional transect of the Southern Atlantic, spanning 36°S to 68°S. Seawater samples were collected using an adaptation of the GEOTRACES clean sampling method concurrent to the austral mid-summer (2015). A multi-element inductively coupled plasma mass spectrometry (ICP-MS) technique, coupled with the commercially available seaFAST pre-concentration module was set up and validated for 8 trace elements (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb). The method proved highly precise (≤10%RSD) in the repeated analysis of an in-house control (TM4A), and accurate in the analysis of the SAFe (D2) international natural seawater reference material. Iron (Fe) quantification proved precise (≤5%RSD) and accurate under repeat analysis. Furthermore, two GEOTRACES standards, GSP and GSC, were analysed for contributing to the determination of their consensus values. DCo concentrations within the oligotrophic sub-surface waters (500m) of the Sub-Tropical Zone (STZ) are heavily depleted (12.57 pmol/kg) owing to strong bio-utilization. Conversely, sub-surface Antarctic Intermediate Waters (AAIW) near the Sub-Antarctic Front (SAF) were elevated (36.1 pmol/kg). Concentrations subsequently decline meridionally through the Antarctic Circumpolar Current (ACC) steadying within the Weddell Gyre (20.3 pmol/kg). STZ DCd sub-surface concentrations are notably depleted (74.1 pmol/kg). However, sub-surface concentrations increase within the ACC at the SAF (450 pmol/kg), continuing into the Weddell Gyre (700.8 pmol/kg). DCd exhibits a typical nutrient-like profile, with bio-utilization in the surface (MLD), followed by regeneration and conservation. The nutrient like behaviour of bio-utilized DCd was exemplified by an excellent Cd/P sub-surface correlation in the ACC, waning somewhat in the sub-optimal productivity of the Weddell Gyre. However, abiotic factors may have contributed to DCd concentrations. The complete water column concentrations ranged from 8.4 ± 0.05 pmol/kg to 902 ± 22.71 pmol/kg. Conversely, DCo demonstrated a typical hybrid-type vertical distribution – nutrient uptake and remineralization in the surface succeeded by scavenging controlled by heterogeneous oxidising bacteria. The complete water column concentrations ranged from 4.1 ± 0.02 pmol/kg to 38.9 ± 0.3 pmol/kg. Elevated DCo concentrations in the sub-surface and a poor but significant DCo/Salinity correlation, suggest DCo flux in the expanse surrounding 46°S and 68°S. Keywords: Biogeochemical cycling, Dissolved Co and Cd, GEOTRACES, ICP-MS, Iron (Fe), seaFAST, Southern Atlantic. AFRIKAANSE OPSOMMING: Die biogeochemiese sirkulering van die bio-aktiewe opgelosde spoor metale kadmium (DCd) en kobalt (DCo), word berig op 'n meridionale transeksie van die Suider-Atlantiese Oseaan, wat van 36 °S tot 68 °S strek. Seewater monsters was ingesamel met behulp van 'n aanpassing van die GEOTRACES skoon steekproefmetode tydens die middel van die suidelike somer (2015). 'N Multi-element induktiefgekoppelde plasma massaspektrometrie (ICP-MS) tegnologie, tesame met die kommersieel beskikbare seaFAST pre-konsentrasie module is opgestel en bekragtig vir 8 spoorelemente (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb). Die metode bewys hoogs akkuraat (≤10% RSD) in die herhaalde analise van 'n in-huis beheer (TM4A), en akkuraat in die ontleding van die SAFe (D2) internasionale natuurlike seewater verwysingsmateriaal. Yster (Fe) kwantifisering bewys presies (≤5% RSD) en akkuraat onder herhaalende analise. Verder, twee GEOTRACES standaarde, GSP en GSC, is ontleed om by te dra tot die bepaling van hul konsensus waardes. DCo konsentrasies binne die oligotrofiese sub-oppervlak water (500m) van die Subtropiese Sone (STZ) is swaar uitgeput (12,57 pmol/kg) as gevolg van 'n sterk bio-benutting. Aan die ander kant was Sub-Antarktiese Front (SAF) sub-oppervlak water (AAIW) verhef (36.1 pmol/kg). Konsentrasies daal daarna meridionally deur die Antarktiese Circumpolaire Huideging (ACC) en bedaar binne die Weddell Gyre (20.3 pmol/kg). STZ DCd sub-oppervlak konsentrasies was veral arm (74,1 pmol / kg). Maar, sub-oppervlak konsentrasies verhoog binne die ACC naby die SAF (450 pmol / kg), voortgesette in die Weddell Gyre (700,8 pmol/kg). DCd toon 'n tipiese voedingstof-agtige profiel, met bio-benutting in die oppervlak (MLD), gevolg deur die wedergeboorte en bewaring. Die voedingstowwe soos gedrag van bio-gebruik DCd is vergestalt deur 'n uitstekende Cd/P sub-oppervlak korrelasie in die ACC, besig om te kwyn ietwat in die sub-optimale produktiwiteit van die Weddell Gyre. Dit kan egter wees dat abiotiese faktore bygedra het tot DCd konsentrasies. Die volledige waterkolom konsentrasies het gewissel van 8.4 ± 0.05 pmol/kg tot 902 ± 22,71 pmol/kg. Aan die ander kant, demonstreer DCo 'n tipiese baster-tipe vertikale verspreiding - voedingsopname en remineralisatie in die oppervlak, opgevolg deur aas beheer tekoms heterogene oksideer- bakterieë. Die volledige waterkolom konsentrasies het gewissel van 4.1 ± 0,02 pmol/kg tot 38,9 ± 0,3 pmol/kg. Verhoogde DCo konsentrasies in die sub-oppervlak en 'n arm, maar beduidende DCo/Zoutgehalte korrelasie, raai DCo vloed in die uitspansel rondom 46 °S en 68 °S. Sleutelwoorde: biogeochemiese sirkulering, opgelosde Co en Cd, GEOTRACES, induktiefgekoppelde plasma massaspektrometrie (ICP-MS), yster (Fe), seaFAST, Suider-Atlantiese Oseaan 2017-02-18T09:48:07Z 2017-03-29T11:47:09Z 2017-02-18T09:48:07Z 2017-03-29T11:47:09Z 2017-03 Thesis http://hdl.handle.net/10019.1/100925 en_ZA Stellenbosch University 154 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD Loock, Jean Christian The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title | The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title_full | The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title_fullStr | The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title_full_unstemmed | The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title_short | The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector |
| title_sort | biogeochemistry of bioactive trace elements cadmium and cobalt in the southern ocean atlantic sector |
| topic | Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD |
| url | http://hdl.handle.net/10019.1/100925 |
| work_keys_str_mv | AT loockjeanchristian thebiogeochemistryofbioactivetraceelementscadmiumandcobaltinthesouthernoceanatlanticsector AT loockjeanchristian biogeochemistryofbioactivetraceelementscadmiumandcobaltinthesouthernoceanatlanticsector |