Old oil spills keep on giving

Wildcatters don’t have to go out to the continental shelf to drill for oil. There’s oil on Wild Harbor in West Falmouth, inches beneath the surface, just like on Jed Clampett’s farm.
That’s not a good thing, but it’s no disaster either.
Buzzards Bay is a transit route for oil and gasoline on the way to Boston, and over the years it has had its share of oil spills, most recently in 2003. With the Woods Hole Oceanographic Institution just a couple of miles down the road, each spill draws some of the top technical people on Earth, so it’s a convenient real-life laboratory.
“I live in Hatchville and our study site is 2 miles away,” Dr. Chris Reddy, an environmental chemist at WHOI pointed out. “Wild Harbor is a key laboratory for us. Oil spills are accidental and we should collect as much information as possible.”
While the Exxon Valdez and the like may get more attention, it was in Wild Harbor that scientists discovered oil can persist for months, and now 30 years, in the environment. And it’s in Wild Harbor and Winsor Cove that Reddy, guest student Jennifer Culbertson and others are pondering the causes and effects of that remnant oil.
“What gets me excited is nature and how it responds to uninvited guests. It could be oil compounds or PCBs in New Bedford Harbor,” said Reddy. “An oil spill is like a giant syringe. You take it and hit some ecosystem with it really fast. Obviously it’s not a good thing but it is a great opportunity to understand how nature works.”
Culbertson looked at fiddler crabs living where the oil persisted and found “great impact” three decades on.
In the Wild Harbor spill on Sept. 18, 1969, the oil barge Florida ran aground and spilled 189,000 gallons of No. 2 fuel oil. Much of it was blown into Wild Harbor. Dead and rotting fish, shellfish, crabs, sea worms and more washed ashore.
WHOI scientists George Hampson, Max Blumer, Jerry Sass and Howard Sanders discovered that while oil may wash away, get cleaned up or broken down by bacteria, at the surface months later it was lingering in the muck. That surprised people.
Twenty years later John Teal and John Farrington found more remnant oil. And as recently as 2002, Reddy and his cohorts discovered “petroleum hydrocarbons” just 12-16 centimeters below the surface.
In Winsor Cove, 5 miles from Wild Harbor, where another barge, the Bouchard 65 dumped thousands of gallons of fuel oil in 1974. Some of it’s still there.
“I’m interested in saying, ‘we had an oil spill, we know this much is left so where did it all go? Why is what’s left still here and what made the compounds that are still present want to stay?’ It’s almost like being a sociologist or psychologist to these chemicals,” Reddy reflected. “It’s a great job. It’s like a crossword puzzle but it’s not frustrating. Often it’s just the way the molecules are built, the subtle way they’re put together makes the difference.”

Oil 101
“There are a thousand different compounds in crude oil,” Reddy noted.
Crude oil isn’t shipped through the Canal, There are no refineries in New England. We get the finished products.
“The crude oil goes to a refinery, which is like a giant distillery,” explained Reddy. “They heat the oil and as it gets heated different classes of compounds distill out. These are called cuts or fractions. One fraction [one of the first] is gasoline. The other products [in order] are diesel fuel, kerosene, home heating oil, heavy oil, light lubricants, etc. and a residue like asphalt.”
As a rule the first distilled fractions are more bioactive, they interact with living organisms.
“Gasoline, pound for pound, is the most toxic,” Reddy said.
On the bioactive scale, gasoline is followed by diesel fuel, kerosene and home heating oil while at the other end, asphalt is quite inert. But gasoline is also the quickest to break down.
“It won’t persist in the environment. On the flipside other residues are not as toxic, but they hang around in the environment a long time, such as tar on a road,” Reddy said. “What’s scariest for me is a diesel fuel or home heating oil spill. They still pack a bioactivity punch and they have an ability to persist in the environment for three decades.”
Two billion gallons of diesel fuel is shipped through Buzzards Bay every year.

Why is the oil still there?
Some of the breakdown of oil is physical, pounding surf and such; some is bacterial, microbes eat it.
“It’s a smorgasbord.” Reddy said. “Many of the components that persist for three decades just aren’t as tasty as what’s left over from a blade of salt marsh grass.”
Not that a decayed blade of grass sets a high culinary standard.
“That’s why people who worry about spills worry about salt marshes. Because they have the potential for persistence versus a rocky beach where the waves are pounding,” Reddy declared. “With oil spills it’s location, location, location.”
In marshy muck, oxygen vanishes half an inch into the peat. There are anaerobic bacteria that can break down oil but they work much slower. So oil that seeps into the anoxic zone may linger for decades.
“A lot of these molecules like to stick to the sediment and mud and once they stick they are no longer easily attacked by microbes,” added Reddy.
After Reddy and his graduate student, Emily Peacock, took cores all around Wild Harbor, they estimated only 95 kilograms (about 25 gallons) out of the original spill remained. The marsh looks pristine, unlike Winsor Cove, but that oil is altering the marsh.

Old oil, new problems
With the oil lurking 12 centimeters down in the muck, Culbertson wanted to study an organism that lived there. She chose the fiddler crab.
They burrow into the peat and nibble on it to glean food. Culbertson examined the burrows of 20 crabs.
“We took plaster of Paris, made sure it was the right consistency and poured it in and let it set. Removing them was the hardest part. We dug with our fingers or a little spade,” she explained. “Right before they detected the oil they tended to curve upward, go horizontally or go back to the surface. They usually go straight down.”
Potentially, that makes the crabs easier prey, and like Manny Ramirez running out a grounder they were also moving kind of slow.
“They are slower, just from looking at them,” Culbertson observed. “The ones in the oiled areas are much easier to pick up. I think they are probably predated on more. There are fewer crabs in Wild Harbor than in Sippewissett marsh, our control marsh nearby. Even the areas in Wild Harbor that have no oil have more crabs. So it does have great impact.”
The crabs also fed more slowly on oil-soaked muck. Culbertson is studying salt marsh grass as well, to see if there are differences in biomass, stem counts, roots, etc. Reddy has noted oil’s effects on the vegetation.
“After the 1969 spill grass died in some locations,” he said. “And we can see that in the 1974 spill the salt marsh is continuing to erode. The grasses have not grown back. It looks like a parking lot in the area most impacted.”
Peacock is now looking at why two harbors are different. Their work shows that while nearly all 1,000 compounds of the fuel oil are still in Wild Harbor, a goodly number have vanished from Winsor Cove.
“What we were amazed at was the oil was still there [at Wild Harbor] and that it hadn’t changed much. That was a major finding for us,” Reddy said. “The oil at Winsor Cove was sitting on the surface and twice a day the tide comes in and out. The bioactive compounds are missing at Winsor Cove.”
But their damage was done long ago.
The Bouchard 120 spilled 350 barrels of No. 6 fuel oil that was bound for the Mirant power plant in Sandwich in 2003. That gives them a chance to observe a spill from day one.
“We’re still working on that spill,” Reddy said. “At the end of the day we want to make a pie chart, an accounting sheet and balance the books.”
Buzzards Bay has 200 miles of salt marsh.
“I feel good about my research,” he reflected. “I’m giving back to the taxpayers data that is useful.”