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Doing the dirty work to save the sinking city of Venice

Three years ago, microbiologist Rick Gersberg left his office at the Graduate School of Public Health at San Diego State University to take on one of the biggest projects of his career: Help save the sinking city of Venice.
His mission: determine the environmental safety of Italy’s $4.5 billion movable tidal barriers that are being constructed to help prevent the flooding of the city by the Adriatic Sea. The concern is these barriers would decrease the tidal flushing of the historic lagoon canals and exacerbate an already serious sewage pollution problem.
“Because Venice is made up of several small islands, there is no sewage system; they just dump their raw sewage right into the canals,” Gersberg said. “Normally, the tides come in and flush everything out. But when you cut off the tide, it just sits there.”
From 2003-2005, Gersberg and his team of students studied the water in the lagoon canals of Venice and at nearby beaches to determine the danger of the current pollution problem. Those findings are published in the current issue of the international peer-reviewed journal Water Research.
A total of 17 water samples were collected over three consecutive summers and processed to determine contamination levels. According to results, 78 percent of the Venice lagoon canals tested positive for both hepatitis A viruses and enteroviruses, which cause common gastro-intestinal illnesses. At Venice’s beach island of Lido, a popular Italian swimming spot separating the Venice lagoon from the Adriatic Sea, hepatitis A wasn’t detected, but enteroviruses were found in all samples.
“Right now, pollution in the Venice canals is below European health standards, and pollution at Lido beach is just near the acceptable level,” said Gersberg.
The current contamination levels will serve as a benchmark for Gersberg’s next step of research, which is to help determine if Italy’s barrier plan will create more dangerous water conditions. Using a model, Gersberg and his team, along with Italian researchers, will duplicate current conditions in Venice and eventually test the effect tidal barriers would have on the already sewage-polluted water conditions.
“What we expect to see is an increase in contamination when the barriers are closed,” Gersberg said. “How bad the contamination gets will depend on how often they are closed. If the sea levels continue to rise at the expected rate, the worry is they’ll have to be closed more and more, causing the situation to become even unhealthier in the canals and causing Lido Beach to be closed down to swimmers more often.”
Though his job might sound unpleasant, it’s nothing compared to the mess the floods from rising tides leave behind on the walkways and plazas of one of the most romantic cities in the world.
“Venetians have lived with this for decades,” Gersberg said. “It’s extremely inconvenient. Residents take boots to work and sirens alert the public when the floods are imminent. Many have moved to upper levels of their homes to prevent some damage, but the outsides of the buildings are eroding because of it. It’s just not something that’s pleasant to live with.”
The flooding is worst in winter when the highest tides coincide with storms in the Adriatic Sea. Many experts blame the greenhouse effect and rising sea levels due to global warming for the increase in tidal overflow.
The vastly debated floodgate construction project began two years ago and is due to be completed in 2012. When finished, a series of 79 inflatable barriers, each 60 feet tall, will lie across the bottom of the lagoon. When high-tide conditions are forecast, the barriers will fill with compressed air and rise to block the incoming water.
Gersberg’s research sabbatical was funded by SDSU’s Office of International Programs, as well as the SDSU Research Foundation. He is one of only a few Americans involved in this major international project.

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