Environmental Geochemistry

The Environmental Geochemistry group conducts multidisciplinary research into biogeochemical processes, environmental change, and the fate of contaminants in the environment. 

Prof. Marc Humphries | Marc.Humphries@wits.ac.za  | Google Scholar

I enthusiastically lead a coherent and independent research program in multidisciplinary environmental geochemistry. My interests in geochemistry and environmental science are diverse, but focus primarily on the links between geochemistry, environmental processes and ecosystem functioning. I am particularly interested in the coastal environment, the geochemical processes that take place within wetland sediments, and how coastal systems respond to environmental change. I use a variety of geochemical techniques to understand how coastal systems function, how they changed in the past, and how they may respond to future anthropogenic impacts and climate change. I have worked on a variety of fascinating coastal and wetland systems across South Africa, Botswana, Tanzania, Madagascar and Australia.

Specific areas of interest include:

• Geochemical and sedimentary processes in wetlands and coastal systems
• Examining climate and palaeoenvironmental change using geochemical proxies
• Contaminant bioaccumulation, ecotoxicology, and the use of novel sentinel species
• Submarine groundwater discharge and the flow of nutrients, carbon and contaminants into the coastal ocean

Dr Letitia Pillay | Letitia.pillay@wits.ac.za  | Google Scholar

My research interests focus primarily on the concentration, behavior and potential remediation of contaminants (both organic and inorganic) in environmental ecosystems, with a particular focus on metal mobility and speciation in plants, sediment, water and to a more limited extent marine biota.

The bioavailability and speciation of metals in environmental and biological samples are key to understanding their toxicity and impact on living organisms. Understanding these parameters allows for assessments to be made on the impact and extent of pollutants on an ecosystem in both the short and long term.

Metal uptake by plants can be a useful tool to facilitate phytoremediation, a cleaner, greener technology for reducing pollutants in contaminated environments. Hyperaccumulator plants can take up elevated concentrations of metals from soils and can have a major impact on successful phytoremediation processes. My current research involves the identification of compounds responsible for hyperaccumulation (and accumulation) in plants and elucidating uptake mechanisms. This will allow for manipulation of uptake processes which in turn may enhance remediation or provide novel techniques for remediation.

Projects include:

• Characterization of the chemical constituents in South African metal hyperaccumulators from the Asteraceae family
• The effect of soil amendments on the rate and capacity of metal uptake in both hyperaccumulator and accumulator species
• Nanomaterials in water remediation
• Metal speciation (arsenic and mercury) in contaminated environments