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Exploring the phytoremediation potential of local South African plants

- Wits Chemistry

How can plants help clean up the environment? A species native to South Africa may hold the key.

This plant has been shown to be able to absorb high quantities of nickel from the soil, making it a potential candidate for use in phytoremediation.

Plant-based technology that uses plants to remove contaminants from soil or water provides a cost-effective and environmentally friendly way to clean up pollution. Su-Ane Greyling, a masters student being supervised by Dr Letitia Pillay, is studying a group of plants called nickel-hyperaccumulators that extract extremely high concentrations of nickel from the environment. The nickel within the plant can be extracted and re-used. Mining using a plant – how cool is that!

Using plants to clean up the environment is called phytoremediation. This is a process whereby heavy metal accumulating plants accelerate the degradation of organic contaminants and reduce the concentration of heavy metals in the soil and aquatic systems. Plants must exhibit certain characteristics to be considered for phytoremediation strategies. Some characteristics include fast growth rate and high biomass production, high heavy metal tolerance, resistive behavior to pathogens and pests, and sufficient adaptivity to environmental conditions – all of these are factors that are being exploited in our research to enhance a plant’s ability to extract the heavy metals from the soil.

Heavy metals are naturally present in the environment (soil and aquatic ecosystems) from sources such as weathering of rocks or volcanic eruptions. However, heavy metal pollution, due to increased anthropogenic activities such as urbanization and burning of fossil fuels, has become one of the most pressing environmental problems in the world.

Traditional approaches to remediation are typically invasive, and therefore greener, environmentally friendly approaches are sought after and in high demand. This is where Su-Ane’s research could potentially play a significant role. Her investigation is focusing on Berkheya zeyheri – a plant native to South Africa that is classified as a nickel-hyperaccumulator. Berkheya zeyheri is only found on serpentine soil – a special type of soil enriched in heavy metals – in the Barberton region of South Africa.

Su-Ane is trying to understand the mechanism by which these plants take up and accumulate metals to try and adapt the plant to grow under other conditions. If the mechanism of action can be understood, then these plants could potentially be used sustainable and environmentally friendly way to clean up pollution in other regions.

Berkheya zeyheri is a nickel-hyperaccumulator