About

The Centre for Trace and Experimental Biogeochemistry, a centre within the Department of Earth Sciences at Stellenbosch University, aims to gain an improved understanding on biogeochemical cycling of bioactive trace elements in marine environments.

South Africa had a rich history in the field of chemical oceanography. Over the past 50 years, however, it has declined and only a skeleton remains which is incapable of meeting the requirements of a country surrounded by three oceans. Deteriorating research facilities combined with a lack of impetus in oceanographic research and funding resulted in South Africa experiencing a significant brain drain and subsequent decline in research capacity. South Africa is currently, however, maturing in its democracy and starting to pay more attention to the socio-economic benefits of the natural environment. Change is on the horizon.

Geographically and strategically, the research centre at Stellenbosch is best-placed to study aspects of the Southern Ocean. It is situated at the confluence of three oceans, namely, the Indian, Atlantic and Southern Oceans. Large sectors of these oceans below Africa are understudied and lack scientific data crucial to global climate models or to ascertain variability trends that will help understand linkages between trace metals, primary productivity, biodiversity and long term climate change.

The Center’s research and training activities focus on the Southern Ocean and Southern African coastal waters with a view to understanding long-term impact on the global carbon cycle, ocean acidification and climate change. More specifically, trace nutrients and their impact on productivity in oceans are studied.  The ultimate goal is to become a South African and African Center of Excellence in the highly specialized field of trace metal biogeochemistry . The Center not only helps to develop capacity for the long-term monitoring of the Southern Ocean and contribute to the global dataset for climate monitoring, but it also undertakes cutting edge scientific work thereby raising the quality and quantity of South African and African research output.

Given the specialized nature of the Center’s work, high-level skills sets and specialized land and ship-based laboratories have been developed. We make use of the state of the art ice-breaker ship SA Agulhas II that is fitted with GEOTRACES approved trace CTD rosette with Teflon coated Go-Flo bottles, a towed fish and two container clean labs for trace clean sampling and experiments. On land we boast a temperature controlled Class 10 clean laboratory equipped with Picotrace® laminar flow workstations, Fe-FIA, Sector filed ICP-MS, anaerobic chamber and temperature and light controlled incubators.

The Center promotes the mandate of the International GEOTRACES program in South Africa

 

 

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RoyRoydchoudhury 003
Prof AN Roychoudhury, Stellenbosch University

My research focus is on biogeochemical dynamics in aquatic environments. In particular I am interested in understanding reaction kinetics and other controls over elemental (carbon, sulfur, nutrients and metals and trace metals) cycling on the global as well as local scales. For more information click here.



Susanne
Dr S Fietz, Stellenbosch University

My research aims to study modern aquatic systems and sedimentary archives as well as sedimentation processes to help interpretation. This approach provides essential information on past and present environmental conditions for those predicting future local and global changes.



Thato
Dr Thato Mtshali, CSIR

My research focusses on the roles of trace metal biogeochemistry, with particular interest of Iron (Fe), and light dynamics in the Southern Ocean primary productivity. This research combines Fe speciation, analytical chemistry, and phytoplankton physiology


 

Research

Phytoplankton serve as the base of the aquatic food web, sustaining all aquatic life. Through photosynthesis, phytoplankton are responsible for most of the oxygen present in the Earth’s atmosphere. Phytoplankton also consume as much carbon dioxide as forests and other land plants. Worldwide, this “biological carbon pump” transfers approximately 10 gigatonnes of carbon from the atmosphere to ocean each year.

Ocean-atmospheric carbon dioxide exchange in the Southern Ocean in particular plays an important role in global climate change. Recent estimates indicate that approximately 50% of all carbon dioxide emitted by human activity is stored in the Southern Ocean. Despite the importance of the Ocean in improving carbon dioxide  levels  and  reducing  the  impact  of  man-made  climate  change,  its  carbon  cycle  remains  poorly understood.

Even small changes in the production of phytoplankton in the Southern Ocean will influence carbon dioxide uptake and release. This will in turn influence global atmospheric carbon dioxide concentrations, surface temperatures, ocean acidification and climate. In addition, changes in production will also affect the ecological food chain, leading to possible negative impacts on marine ecosystems and biodiversity.

Biologically important trace metals (iron, manganese, cobalt, nickel, copper, zinc and cadmium) are essential for ocean primary productivity – phytoplankton production. Without their presence, production cannot take place. It is therefore important to understand how the bioavailability of these trace elements (the amount available for absorption and utilisation by phytoplankton) increase or limit phytoplankton growth and also how their rate and mode of occurrence influence this growth.

Laboratory Facilities


Flow-injection Analyzer (Fe)

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A highly sensitive flow injection analysis with Chemiluminescence detector (FIA-CL) is installed for determining the concentration of iron in seawater. The equipment is linked to an auto sampler allowing for multiple analyses without the need for constant monitoring. The developed method is an improvement on similar available methods and uses commercially available resin (IDA) as oppose to the one that requires synthesis in the laboratory. Furthermore, the method requires reduced reagent concentrations thereby providing better results in a cost-efficient and easy manner. The improvements resulted in better precision while eliminating the loss of resin through bleeding, a common problem when using 8-HQ resin as per prior methods. The instrument performance is validated using internationally calibrated reference material (SAFe) provided by GEOTRACES and the values obtained are within the error limits of certified range.


seaFASTTM-pico SC-4 DX (Elemental Scientific Inc.)

seaFAST

This is a completely automated sample introduction system for multi-mode determination of ultra-trace metals in undiluted seawater using ICP-MS. The system can be used in direct mode or pre-concentration mode. Our lab uses this system primarily in pre-concentration mode and is routinely used for analyses of:

Fe, Mn, Co, Cd, Zn, Cu, Ni, Mo, Pb and REE.

The method for simultaneous measurement of trace metals using seaFAST system in conjunction with ICP-MS (Agilent® triple quad, 8800) has been validated using GEOTRACES SAFe, GSC and GSP standards.


PicoTrace® sediment acid digestion system

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For measurement of trace metals in marine particles we have a corrosion protected system to transfer solid samples to solutions using strong acids (HF, HCl, HNO3, and, H2SO4) under elevated temperature and pressures. The digestion vessels are made from ultra clean TFM. Evaporation of the acids takes place under a closed system. Up to 32 samples can be digested at the same time.


PICARRO L2130-i δD and δ18O High-Precision Isotopic Water Analyzer

Picarro isotope analyzer

Picarro’s L2130-i is a cavity ring down spectrometer that provides a platform for advanced research into all aspects of the water cycle: water vapor, liquid water, or water trapped in solids. The instrument is used for measurement of hydrogen and oxygen isotopes of water. This field deployable analyzer has a full suite of accessories for preparation of the different sample forms and can be deployed on the ship for continuous measurement while steaming.

 

 

 

 


PICARRO G2201-i CRDS Analyzer for Isotopic Carbon in CO2 and CH4

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The G2201-i cavity ring down spectrometer is used for analyzing  the isotopic carbon ratio in both CO2 and CH4  at the same time. This instrument combines the capabilities of Picarro’s two carbon isotope instruments for CO2 and CH4 into a single instrument to gather the insights that stable isotope ratios offer. The spectrometer is linked to a combustion module for analyzing isotopic ratios in solid samples. It is small in size and robust, which makes it easy to transport to the field where immediate and continuous results can be obtained.


Other equipment

A number of other equipment are available that include high precision balances, temperature/light controlled incubators, freeze drier, spectrophotometer and FTIR.

The center also has access to other large equipment such as ICP-MS, Atomic Force Microscope, CT-Scanner, SEM, LC-MS, GC-MS, and Flow cytometer through the Central Analytical Facility of Stellenbosch University for imaging and assessing chemical signatures in biogenic and lithogenic systems.