Thirty years after the barge Florida spilled approximately 700,000 liters of fuel oil off the coast of West Falmouth, Mass. in Buzzard’s Bay, core sediment samples from a salt marsh in nearby Wild Harbor still show traces of the spill, according to newly published research in ES&T (10.1021/es020656n). Despite a healthy appearance in the marsh, Christopher Reddy and colleagues at the Woods Hole Oceanographic Institution (WHOI) and U.S. Coast Guard Academy (USCGA) report that oil trapped in anoxic sediments 6–28 centimeters below the surface has not weathered or degraded significantly since the spill. However, a sophisticated method provides new details about oil composition.

Compared to the 40-million gallon Exxon-Valdez oil spill, West Falmouth was not big but is historically one of the most studied diesel spills and an important record of oil fate and effects, says John Farrington, vice president for academic affairs and dean at WHOI. Max Blumer, a geochemist at WHOI, analyzed mud from the day after the spill and shellfish within weeks by gas chromatography. Farrington says Blumer’s controversial and frequently cited studies with biologists John Teal and Howard Sanders at WHOI in the 1970s were at the forefront of research that influenced environmental legislation. He recalls up to that time, spilled oil was a known financial loss and made beaches messy. When these researchers showed that oil did not just quickly “disappear” as everyone then believed, but had “demonstrable biological effect well beyond the first few days into months and years,” the world was forced to respond to an environmental hazard, says Farrington.

“[West Falmouth] is a model for why we need long-term environmental studies,” say Kathy Burns, a research scientist at the Australian Institute of Marine Science who did her 1975 doctoral thesis on West Falmouth with Teal. Prompted by the Exxon Valdez publicity, she, Teal, Farrington, and others reassessed shellfish and sediment chemistry in 1989 and found the characteristic “hump” of petroleum products in the gas chromatograms had not changed significantly in 20 years.

Reddy “believes that the oil at this location will persist in the sediments indefinitely” because the salt marsh experiences little tidal flushing—like how “dust collects in a corner”. Moreover, microbial activity is very low, probably because of a lack of electron acceptors, such as sulfate, which are needed to degrade organic matter. Reddy speculates that the microbes may have been too busy “breaking down old plant debris and didn’t have enough sulfate to help biodegrade the oil.”

In the current research, Reddy says they resolved the “hump” with two-dimensional gas chromatography (GC×GC) because traditional GC does not have the probing power for a mixture as complex as petroleum. Samples injected into a GC×GC instrument pass through two columns with different separation chemistries and temperatures in series. Knowing that the “hump” includes branched alkanes, cycloalkanes, substituted benzenes, naphthalenes, and fluorenes could help in cleaning up future spills, says Reddy. In a paper scheduled to publish in ES&T, coauthor Glenn Frysinger, a chromatographer at the USCGA, reports using GC×GC to further separate alkane compounds previously isolated with column chromatography. Frysinger says identifying each separated compound will be the next step.

Reddy wants to focus on why the oil still exists. He plans to inject sulfate into the contaminated layers in an attempt at remediation, but results will not be available for at least a year. Joseph Suflita, a microbiologist involved in anaerobic remediation studies of petroleum at the University of Oklahoma cautions “what can be done [by microbes] may have been done already.” He says some of the reported compounds are consistent with what is expected when anaerobic microbes attack hydrocarbons. —RACHEL PETKEWICH