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Microbes in the water may have a greater capacity to devour fuel waste than originally thought, a new study has found, suggesting the harbor could cleanse itself within 20 years, barring any major fuel leaks.
The study was co-authored by Derek Lovley, a microbiologist at the University of Massachusetts, who stated, "It is optimistic It is realistic."
The Boston Harbor's pollution problem was introduced to a broad audience in the Standells' 1966 ode to Boston, "Dirty Water." More recenlty, in 1988, George H.W. Bush helped sink Massachusetts Gov. Michael Dukakis' presidential bid by touring the harbor to highlight its filth.
The water quality has greatly improved after a multibillion-dollar cleanup effort including the construction of the Deer Island Sewage Treatment Plant but problems remain.
If it's true the pollutants will break down naturally, the expensive and potentially damaging dredging of the harbor floor to get remaining waste could be avoided.
But Eugene Madsen, a Cornell University microbiologist, warned the study contains no basis for the UMass predictions.
Some of the contaminants in the sludge remained untouched in the experiment and Madsen is skeptical about the amount of biodegradation reported on certain compounds. It's also unproven if the results in the simulation are actually happening in the harbor itself, making a 20-year timetable for self-cleaning unrealistic, he said.
Still, Madsen said, the study offers more proof that some contaminants not previously thought to be biodegradable may be naturally breaking down.
"The case is being strengthened," Madsen said. "There's more evidence now than there was before."
The Navy-funded research at UMass challenged the longheld assumption that petroleum contaminants, called polycyclic aromatic hydrocarbons, or PAHs, could not degrade once they sank into the muddy harbor bottom, where there's little oxygen.
Previous experiments have shown that benzene degrades in the absence of oxygen. The harbor's waste is essentially groups of benzene rings, so scientists figured it was worth a shot.
"The likelihood was that it wouldn't work, but it seemed worthwhile to test it," Lovley said.
The scientists took sediment from an area of the harbor known as Island End, located in Everett near a former coal tar plant. After monitoring the samples for 338 days, they found the PAHs broke down 20 percent to 25 percent.
The key appears to be the presence of sulfate, a salt of sulfuric acid which is abundant in seawater, Lovley said. The microbes appear to use it as a substitute for oxygen, breaking down the waste in the same way humans use oxygen to break down their food.
The UMass research, published recently in the journal Environmental Science and Technology, was centered in Boston Harbor, but the process is not unique to it.
The researchers tested sediment from Tampa, Florida, San Diego and Latvia to ensure the cleansing was not just a product of local environmental conditions, Lovley said.
Bruce Berman of Save the Harbor/Save the Bay, a nonprofit group that works to restore and protect Boston Harbor and Massachusetts Bay, said he welcomed the news, if it's true.
But he added any self-cleansing properties in the harbor shouldn't be used to let oil companies off the hook for past and future spills.
"If there were never any more oil going into the harbor, this would be really good news," he said. "Since there is, it's pretty good news."