Marine seaweed can detoxify organic pollutants

Researchers have discovered that marine seaweeds have a remarkable and previously unknown capacity to detoxify serious organic pollutants such as TNT or polycyclic aromatic hydrocarbons, and they may therefore be able to play an important role in protecting the ecological health of marine life.

The studies, conducted by scientists from the College of Engineering at Oregon State University and the Marine Science Center at Northeastern University, were presented today at the annual meeting of the American Association for the Advancement of Science.

The findings may have important implications for seafood safety, since some of the marine organisms most at risk from these toxins are marine invertebrates such as clams, shrimp, oysters or crab that tend to “bioaccumulate” them. One possibility, the researchers say, might be to plant appropriate seaweeds as a protective buffer around areas being used in aquaculture. “We found that certain red seaweeds had an intrinsic ability to detoxify TNT that was 5-10 times faster than any known terrestrial plant,” said Greg Rorrer, a professor of chemical engineering at OSU. “Marine seaweeds have a more efficient uptake mechanism than even terrestrial aquatic plants to at least neutralize organic pollutants. “The researchers call this process “phycoremediation,” derived from phykos, a Greek word for seaweed.

The studies, which are supported by the Office of Naval Research and the Oregon Sea Grant Program, are of particular interest in the case of trinitrotoluene, or TNT, because of unexploded bombs or military shells found in some places around the world’s oceans. There is a general concern these shells could potentially corrode. “It’s important to know how corals, fisheries and plant life might respond to exposure to TNT or other toxins,” Rorrer said. The study is looking at not just TNT, which is commonly found in munitions, but at polycyclic aromatic hydrocarbons, such as naphthalene, benzopyrene and other PAHs that are sometimes associated with the use of motorcraft or other causes.

Ongoing studies found that marine seaweeds processed toxins to a much less harmful form, and in a way that did not appear to harm the seaweed. The biochemistry involved, they say, is similar to that found in many land organisms, but more powerful and effective. Until now, the capability of marine seaweeds to deal with these toxins had never before been demonstrated. It’s unclear yet whether similar plants can be identified, the researchers said, that will perform this function in terrestrial fresh waters, such as streams or lakes.

These research outcomes should lead to the development of new bioremediation technologies that use seaweed in engineered systems to remove organic contaminants from the marine environment, the scientists said.

Studies to create genetically engineered seaweeds that perform these functions even better are also promising, the researchers said.