Lowly Earthworm Sucks Toxins From Poisoned Soil

Jul 29th, 2012

Rapidly expanding populations in developing nations result in an overwhelming amount of solid and organic waste. In many of these small, struggling nations, there are few or no managed landfills. Much of the waste is simply dumped on the ground near the edge of town. These open air garbage dumps put people at risk for disease and pollute the environment.

In many cases, solid waste leaches heavy metals, cadmium, copper, lead, manganese, and zinc into the soil and water. Now, researchers at India’s Pondicherry University think that wriggling pink earthworms may be the secret to affordable bioremediation of these contaminated sites. How? By doing exactly what they do in your home compost pile.

According to the researchers, Eudrilus eugeniaeEisenia fetida and Perionyx excavates earthworms appear to have digestive systems that are capable of detaching heavy metal ions from the complex aggregates between these ions and humic substances in organic waste as it rots. Now, everything that goes into an earthworm’s mouth eventually appears again on the other end, but scientists say when it comes to these heavy metals, that’s not the case. Various enzyme-driven processes then seem to lead to assimilation of the metal ions by the worms so that they are locked up in the organism’s tissues rather than being released back into the compost as worm casts.