Scientists hone technique to safeguard water supplies

Aug 28, 2009

A method to detect contaminants in municipal water supplies has undergone further refinements by two Oak Ridge National Laboratory researchers whose findings are published on line in Water Environment Research.

The new work demonstrates that the technology that uses algae as sentinels has broader applications than previously reported, according to authors Miguel Rodriguez Jr. and Elias Greenbaum of the Department of Energy's ORNL. For example, under real-world operating conditions, the sensitivity of the algae to toxins has a natural daily cycle that tracks the sun.

"When the sun is overhead and shining brightly, the algae are less sensitive to the toxins," Greenbaum said. "The new work shows that keeping the sample in darkness for about 30 minutes prior to testing for toxins restores full sensitivity to the test."

The new results also show that the technology can be applied to many different water quality environments such as when the algae are starved for nutrients.

"Our key result is that despite real-world conditions that create challenges, free-living microalgae combined with 'work-around' strategies can be used as broad-spectrum automated biosensor systems for continuous monitoring of source drinking water," Greenbaum said.

The process uses a fluorometer to measure the fluorescence signal of algae that grow naturally in source water such as Tennessee's Clinch River, which was used in this study. Researchers exploit the known characteristics of Photosystems I and II, which convert light energy into , to detect any changes in the process of .

"Recent advances in optoelectronics and portability make this a powerful technology for monitoring the in situ physiology of aquatic photosynthetic organisms such as green and cyanobacteria," the authors wrote. Even low levels of toxins alter fluorescence patterns within minutes.

Another significant aspect of this work is the reporting of statistically reliable data on the threshold detection levels for broad classes of toxins such as blood and nerve agents and agrochemicals. These levels are at or near Environmental Protection Agency regulatory guidelines, Greenbaum said.

For this study, the researchers looked at five classes of chemical agents in water: Diuron, atrazine, paraquat, methyl parathion and potassium cyanide. All are known to be harmful to human health. In the case of Diuron, used in agriculture for 50 years, Greenbaum and Rodriguez were able to detect 1 part per million. This was indicated by a 17 percent decline in the algae's Photosystem II efficiency.

"We have shown that microalgae in source drinking water can be used as broad-spectrum, robust sentinel sensors to detect relatively low concentrations of toxins," Greenbaum said. "We have also shown that the microalgae do not need to be in an optimized state for this technology to be effective."

Source: Oak Ridge National Laboratory (news : web)

Explore further: Strengthening community forest rights is critical tool to fight climate change

add to favorites email to friend print save as pdf

Related Stories

Technology can protect water supply

Jan 07, 2005

A technology to instantly determine a poisoned water supply system has been developed at the Department of Energy's Oak Ridge National Laboratory. Researcher Eli Greenbaum said the AquaSentinel system can detect toxins in ...

Noxious algae gone, but who knows how long

Jan 03, 2007

Recent storms may have washed away algae blooms in a Florida chain of lakes, but experts said algae threats remain because of pollution feeding the lakes.

DNA tests could help predict, prevent harmful algal blooms

Sep 30, 2008

A paper published in the current issue of the International Journal of Environment and Pollution, explains how a DNA test can be used to detect harmful algal blooms across the globe. The approach outlined could help reduce ...

Engineering algae to make fuel instead of sugar

Dec 17, 2008

In pursuing cleaner energy there is such a thing as being too green. Unicellular microalgae, for instance, can be considered too green. In a paper in a special energy issue of Optics Express, the Optical Society's (OSA) ...

ORNL, Southern Cal set sights on preventing blindness

Mar 19, 2009

Blindness in millions of people with diseases that starve eye tissue and nerves of oxygen might be averted with a procedure being developed by researchers at Oak Ridge National Laboratory, the University of Southern California ...

Recommended for you

EU sets new energy savings target at 30%

4 hours ago

After months of tough negotiations, the European Commission recommended Wednesday a new energy savings target of 30 percent so as to combat climate change and ensure self-sufficiency.

User comments : 0