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Scientists Use Algae To Measure Water Pollution

August 15, 2008

Researchers in Israel have discovered a new technique to determine water pollution levels by listening to sound waves produced by tiny pieces of floating algae.

The sound waves can be used to identify the type and amounts of contamination in the water.

“It is a red light, telling us that something is beginning to go wrong with the quality of water,” Zvy Dubinsky, an aquatic biologist at Bar Ilan University in Israel, told Reuters.

“Algae is the first thing to be affected by a change in water quality.”

Nearly half of world’s population live in places with high water stress, a number that will most likely increase due to rising population and other factors such as global warming.

Dubinsky said using the algae to test and monitor water quality provides a lower cost, faster and more accurate technique than those in use today, which will be important amid worsening water sources.

The key is to measure the rate of photosynthesis in the algae, he said, referring to the plant’s ability to convert light into energy.  Plants also release oxygen into the air during this process.

Dubinsky’s technique is simple to perform due to the over-abundance of algae in the world’s water supplies.  Indeed, most of the oxygen in the Earth’s atmosphere originates from algae.

The scientists used a prototype tester about one square meter in size that shot a laser beam at water samples to stimulate photosynthesis in the algae.  Some of the laser’s heat goes unused by the algae and is sent back into the water based on the condition of the algae and the photosynthesis rate. This returned heat creates sound waves that can be measured and analyzed with special underwater equipment, Dubinsky explained.  The strength of these returned sound waves are then used to determine the health and contamination levels of the algae and the surrounding water.

“Algae suffering from lead poisoning, like waste discharged from battery and paint manufacturing plants, will produce a different sound than those suffering from lack of iron or exposure to other toxins,” Yulia Pinchasov, a researcher involved with the study, told Reuters.

Testing algae photosynthesis can determine water quality more accurately and easily than current methods such as chemical and radioactive carbon testing, she added.

Dubinsky said with proper investment a commercial product could be available in about two years.

The research has been published in numerous scientific journals, most recently in the journal Hydrobiologia.

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