Underwater vacuum to clean city lake - In: Bangkok Post, Nov. 19th 2007

Pollution threatens the lake that is the heart and soul of Vietnam´s capital - and a legendary turtle who lives below his murky waters - but now a high-tech solution maybe at hand to save them both. Over the next three years in time for Hanoi´s 1000th birthday in 2010, scientists intend to clean up Hoan Kiem Lake, home to the creature that symbolises Vietnam´s centuries-old struggle for independence.

Vietnamese and Germen experts say they will use a new device, which borrows from the design corkscrew, submarines and tanks, to suck several metres of toxic sludge from the bottom of the Lake of the Returned Sword. The $2.4 million (75.8 million bath) project will be a delicate one.

The famed, algae-green lake is home to an elusive turtle that is a key figure in Vietnam folklore. In a story that every Vietnamese child learns at school, the 15th century farmer-turned-rebel leader Le Loi used a magical sword to drive out Chinese invaders and found the dynasty named after him. When Le Loi, by now the emperor, went boating on the lake one day, a turtle appeared, took his sacred sword and dived to the bottom of the lake, keeping the weapon safe for the next time Vietnam may have to defend its freedom.

Today, occasional sightings of a giant soft-shell turtle draw large crowds, and photographs and amateur video clips attest to the claim that at least one turtle indeed still lives in the lake. The turtle legend is a staple of traditional water-puppet theatre, and reported sightings of the animal, a symbol of eternity, are deemed auspicious, especially when the coinside with major national events.

"Since 1991 the turtle has come up about 400 times," said Vietnam´s preeminent authority on the animal, Professor Ha Dinh Duc of the Hanoi University of Science - better known here as the "turtle professor". "Several times, when it came up, it coincided with important events," he said. "It´s something we can´t explain."

The turtle has appeared when Chinese presidents have visited, during the inauguration of a Le Loi statute, at the start of last year´s Communist Party congress, and even during a conferece on endangered reptiles, Duc said. The professor says, he doesn´t know the age of the turtle - which he says is a new species he has named Rafetus leloiiis. He says it weighs around 200 kg.

Previously, at least four of the turtles lived here - one of them is now stuffed and on display in an island temple on the lake - but today only one is left and Duc frets about it well-being. From his Hanoi home, crammed with turtle books, pictures and paraphernalia, he has pushed for efforts to save the turtle, also proposing to catch animals of the same species from another pond to mate with it. "There has been coffee shop talk about cloning the turtle," he said, "but I would oppose it." The more immediate threat to the turtle is man-made.

Stormwater run-off the growing city has sullied the stagnant lake with chemicals ad organic pollutants that feeds algae blooms and choke off oxygen. "The water quality is decreasing, and we expect a breakdown of the aquatic habitat within a decade," said Professor Peter Werner of Germany´s Dresden university of Technology. "The lake could be dead in 10 years."

Hoan Kiem Lake, about 600m long and 200m wide, is now only about 1.5m deep while a four-to-six-metre deep layer od slugde has accumulated on the lake bed, said Christian Richter of German company HGN Hydrogeologie. German scientists have developed a "subaquatic vacuum cleaner" that will crawl along the lake floor using two corkscrew-like spiralsthat dig up and funnel the mud into a pipe while also propelling the device forward.

The remote-controlled "SediTurtle" will use buoyancy to rise and sink like a submarine and use brakes on its two coils to move left and right like a tank, said engineer Dr. Frank Panning of company GSan Ökologische Gewässersanierung. We are using low-impactenvironmental technology that is silent and minimizes turbulence and the release of toxic compounds," said Werner. "This project is very sensitive. We have to take care of the turtle."

In the first phase, set to start early next year and take 24 months, scientists will first analyse water and sediment samples from Hoan Kiem and test the SediTurtle in another Hanoi lake. "If all goes well, Vietnamese experts could then take over and use the new technology to clean up the famous lake itself", said Werner. Duc - whose support is deemed crucial for any project involving Hoan Kiem Lake - has given the green light after vetoing earlier offers for help from Japan, Thailand and elsewhere.

"Many international organisations have offered to help," he said. "This project is environmentally sound, and it´s good for the turtle. And the turtle is important for Vietnam."


Written by Frank Zellner, AFP

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