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Seaweed Cleans Up

By Birgit Reinert

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Toxic Cleanup

Seaweed is everywhere. It is found in soaps and toothpastes, eaten with sushi, and used as a fertilizer. Australian and British scientists have now found another use: Seaweed can help clean up contaminated soil, a process known as bioremediation.

Red seaweed (Gelidium species). The right amount of powdered seaweed helps to degrade DDT.

The scientists sprinkled powdered seaweed on soil that was contaminated with the pesticide DDT and found that 80 percent of the toxic chemical was gone in six weeks. Adding small amounts of seaweed to soil facilitates the breakdown of DDT by microbes.

Green seaweed (Ulva species).

“Seaweed is a source of carbon, which stimulates the growth of certain microbes in the soil,” explains Ian Singleton, a biologist of the University of Newcastle upon Tyne in Great Britain . Seaweed also contains sodium, which makes the DDT more accessible to the microbes.

It could potentially take up to a year to clean up “a contaminated site at full scale,” notes Singleton. The research appeared in the Journal of Chemical Technology and Biotechnology.

Detailed view of red seaweed (Gelidium species).

Even though DDT is banned in most parts of the world, it is still used as a pesticide in some countries in the fight against malaria. The pesticide is blamed for a range of health and environmental problems, and it remains in the environment for decades.

All images are copyright Michael D. Guiry. More images of seaweeds can be found at AlgaeBase.

Kantachote, D. et al. Bioremediation of DDT-contaminated soil: enhancement by seaweed addition. J Chem Technol Biotechnol 79, 632-638 (June 2004).

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