Bioterrorism early-warning system--algae?

Suppose a terrorist cell poisoned a municipal drinking-water supply--a green plant cell could be the key to saving lives after such an attack. Researchers at the Oak Ridge National Laboratory (ORNL) have devised a fluorescence technique using naturally occurring algae in primary-source drinking water to spot water that has become suddenly tainted.

Algae grow naturally on and near the surface of surface-exposed drinking-water sources by using the energy of sunlight and carbon dioxide in the air. Through photosynthesis, healthy algae absorb a considerable amount of light, but they "leak" a little bit of it, according to Eli Greenbaum, a researcher in ORNL's Chemical Sciences Division (CSD). Greenbaum and CSD research assistants Miguel Rodriguez and Charlene Sanders found that this light leakage gives healthy algae a fluorescence signature that can be measured by a standard fluorometer and recorded by a computer.

"If algae in drinking water are exposed to a poison such as potassium cyanide, methyl parathion, or the herbicides Diuron or Paraquat, the algae become unhealthy," said Greenbaum. "The plants then leak more or less light than is usual."

In low concentrations the chemicals Greenbaum named can damage the kidneys, the central nervous system, or the respiratory system. In high concentrations, they can kill people.

The researchers found that algae exposed to any of these poisons in drinking water give off a detectable fluorescence signature that is different from that of normal, healthy algae. They observed that the differences between the fluorescence signatures of algae in ambient water and those of algae in poisoned water could be determined by a fluorometer linked to a laptop computer.

"Our AquaSentinel[SM] can detect a broad spectrum of poisons in water and send up a red flag," Greenbaum says. "It is not as sensitive as a gas chromatograph mass spectrometer system, but it is sensitive enough to trigger an alarm indicating that a city's drinking water may be unsafe. AquaSentinel uses no reagents, and it can run continuously without being attended."

With funding from the Defense Advanced Research Projects Agency, the researchers have developed a field-deployable system. They are testing this prototype AquaSentinel at a continuous pumping station on the Clinch River near ORNL's robotics research laboratory.

Further development of AquaSentinel will be funded by United Defense, a U.S. government defense contractor headquartered in Arlington, Virginia. United Defense has an option to be the first company to license the AquaSentinel technology.

David E. Hill of ORNL's Metals and Ceramics Division is helping the CSD researchers develop a database of a variety of algae signatures and software that will enable the computer to match detected and recorded signatures. Hill also is developing Internet access to the database.

AquaSentinel will be designed to warn municipal reservoir managers that the water supply may have been poisoned. They can then decide whether to shut off the water intake to protect a city's population from a possible terrorist threat.

For information on AquaSentinel, contact Eli Greenbaum by phone at [phone] or by e-mail at [e-mail]. (Adapted, with permission, from ORNL Review, www.ornl.gov/ORNLReview/, Vol. 36, No. 2, 2003, a publication of the Oak Ridge National Laboratory.)