Biochar shown to reduce risks of DDT-contaminated soil

Researchers from Chalmers University of Technology in Sweden have identified biochar as a promising method to reduce the ecological risks of DDT-contaminated soil. Biochar, a substance similar to charcoal, has been shown to effectively bind the toxic pesticide DDT, preventing its uptake by soil organisms. This promising development in soil remediation was published in the journal Science of The Total Environment and has garnered attention for its potential to transform contaminated land management practices while supporting broader environmental sustainability goals.

DDT (dichlorodiphenyltrichloroethane), a chemical known for its persistence in the environment, poses significant ecological threats long after its use has been discontinued. Historically used extensively for pest control in forestry and agriculture during the 1950s and 60s, DDT contamination remains a critical concern. Despite being banned over fifty years ago, residues of DDT still plague numerous sites across Sweden and globally.

The recent study conducted at a former tree nursery in southern Sweden revealed that mixing biochar into DDT-contaminated soil could halve the DDT uptake by earthworms, a key indicator of soil health. This finding suggests that biochar not only reduces the bioavailability of DDT but also diminishes its potential ecological damage.

Lead researcher Paul Drenning and his team at Chalmers have been working on this innovative approach to manage contaminated lands more effectively and sustainably. “By integrating biochar, we observed a 50% reduction in DDT absorption by earthworms, highlighting a decrease in the soil’s toxicity and a lower risk of the toxin entering the food chain or leaching into water sources,” explains Drenning.

This method offers a cost-effective and environmentally friendly solution to rehabilitate land, making it viable for agriculture without the extensive costs associated with traditional remediation techniques, which often involve removing and disposing of contaminated soil. Additionally, biochar contributes to long-term carbon storage in the soil, aligning with climate change mitigation efforts.

The versatility of biochar extends beyond just DDT, with potential applications for stabilizing other contaminants such as metals and polyaromatic hydrocarbons. The ongoing research at Chalmers will further explore the scalability of this treatment, aiming to apply biochar directly into soils without extensive excavation.