The biogeochemistry of bioactive trace elements cadmium and cobalt in the Southern Ocean, Atlantic Sector
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 adaptatio...
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ftunstellenbosch:oai:scholar.sun.ac.za:10019.1/100925 2023-11-12T04:04:59+01:00 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. 2017-02-18T09:48:07Z 154 pages : illustrations application/pdf http://hdl.handle.net/10019.1/100925 en_ZA eng Stellenbosch : Stellenbosch University http://hdl.handle.net/10019.1/100925 Stellenbosch University Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD Thesis 2017 ftunstellenbosch 2023-10-22T07:39:03Z 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 ... Thesis Antarc* Antarctic Southern Ocean Stellenbosch University: SUNScholar Research Repository Antarctic Southern Ocean The Antarctic Austral Weddell |
institution |
Open Polar |
collection |
Stellenbosch University: SUNScholar Research Repository |
op_collection_id |
ftunstellenbosch |
language |
English |
topic |
Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD |
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 |
topic_facet |
Biogeochemical cycles -- Southern Atlantic Cobalt Cadmium Biogeochemistry UCTD |
description |
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 ... |
author2 |
Roychoudhury, Alakendra N. Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. |
format |
Thesis |
author |
Loock, Jean Christian |
author_facet |
Loock, Jean Christian |
author_sort |
Loock, Jean Christian |
title |
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_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_sort |
biogeochemistry of bioactive trace elements cadmium and cobalt in the southern ocean, atlantic sector |
publisher |
Stellenbosch : Stellenbosch University |
publishDate |
2017 |
url |
http://hdl.handle.net/10019.1/100925 |
geographic |
Antarctic Southern Ocean The Antarctic Austral Weddell |
geographic_facet |
Antarctic Southern Ocean The Antarctic Austral Weddell |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
http://hdl.handle.net/10019.1/100925 |
op_rights |
Stellenbosch University |
_version_ |
1782341829960663040 |