WOODS HOLE, Massachusetts - Thirty years after an oil spill near West Falmouth, Massachusetts, residues of the oil can still be found in salt marsh sediments.
In September 1969, about 175,000 gallons of No. 2 fuel oil spilled from the barge FLORIDA in Buzzards Bay near West Falmouth. A report to be released November 15 by scientists at the Woods Hole Oceanographic Institution (WHOI) and colleagues at the U.S. Coast Guard Academy provides evidence that oil from such spills persists in the marine environment for a long period of time even though the surface sediments recover and appear healthy.
Lead study author Christopher Reddy, an assistant scientist in the Institution's Marine Chemistry and Geochemistry Department, and colleagues collected a 36 centimeter (14 inch) sediment core from the West Falmouth site in August 2000. No evidence of petroleum residues were detected in the top six centimeters (just over two inches) or the lower eight centimeters (about three inches) of the core.
However, the central section of the sediment core, from six to 28 centimeters (two to 11 inches from the top of the core) contained petroleum hydrocarbons in similar concentrations to those observed just after the 1969 spill.
Using new analytical methods not available in prior studies at the site, the team found that compounds consistent with No. 2 fuel oil were still present in the sediments and may remain there indefinitely.
The West Falmouth oil spill site is a considered a baseline for studies of the long term fate and effects of petroleum hydrocarbons in marine sediments. Scientists have been studying the site ever since the spill occurred and have found similar results each time.
A 1989 study, for example, confirmed the presence of oil residues in the sediments, attributed to the heavy contamination of the area by the oil spill, the high organic carbon content, and anoxic conditions in the salt marsh sediments that hindered microbial degradation.
Reddy and his department colleagues Timothy Eglinton, Aubrey Hounshell, Helen White and Li Xu have begun a major effort to revisit the spill site and to investigate the fate of the spilled oil using new analytical approaches that were not available in prior studies.
"Petroleum residues from the spill continue to occur in Wild Harbor sediments after 30 years and will likely remain there indefinitely," Reddy said. "Even after all these years, concentrations of some compounds are similar to those observed immediately after the spill and reflect the persistent nature of No, 2 fuel oil in coastal salt marsh sediments."
"The long term biological effects of oil contamination at this site is unknown since animals burrowing into these sediments can be exposed to high levels of some of these compounds," Reddy added. "It is clear from this study that oil spills can have a long term impact on a coastal environment."
The study appears in the journal "Environmental Science and Technology."
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