Biochar shown to reduce risks of DDT-contaminated soil
Dichlorodiphenyltrichloroethane (DDT) soil pollution is still a major problem in many parts of the world. Researchers at Chalmers University of Technology, Sweden, have developed a new method to manage ecological risks from ...
The legacy of previous generations' use of the insecticide DDT still affects us today. During the 50s and 60s, the substance was used to control pests in forestry and agriculture, and although it has been banned for over 50 years, in Sweden alone there are thousands of sites where the soil is still DDT-contaminated. Many other countries around the world have the same problem.
The toxin has been linked to a variety of negative health effects in humans and animals, and it breaks down very slowly. It poses an ecological risk because it can be taken up by terrestrial organisms such as earthworms. When these are in turn eaten by birds and other animals, DDT begins to accumulate within the food chain, which means that the top predators are affected by the highest toxin concentrations.
For three years, researchers at Chalmers University of Technology have been testing a new method to reduce the ecological risks of the toxin at a DDT-contaminated former tree nursery in southern Sweden.
"In our field experiment, we mixed the soil with biochar and grew different plants. We found that biochar binds DDT efficiently, so that it is not taken up by soil organisms," says Paul Drenning, postdoctoral researcher at the Department of Architecture and Civil Engineering at Chalmers, and the first author of the study published in the journal Science of The Total Environment.
Biochar binds DDT effectively, so that the toxin is not taken up by soil organisms. Credit: Anja Enell, the Swedish Geotechnical Institute.
The researchers dug out soil, put it in piles and mixed biochar into half of them. They then set up 24 experimental plots and distributed the soil piles to them in a randomized experiment. The results later showed that the amount of DDT taken up by earthworms in the soil decreased by an average of 50 percent when the soil had been mixed with biochar. Credit: Chalmers University of Technology
The researchers dug out soil, put it in piles and mixed biochar into half of them. They then set up 24 experimental plots and distributed the soil piles to them in a randomized experiment. The results later showed that the amount of DDT taken up by earthworms in the soil decreased by an average of 50 percent when the soil had been mixed with biochar. Credit: COWIfonden