Digital Extra

For most of the week after the spill of 828,000 gallons of oil from the barge North Cape, the majority of official comment, public attention and hard work focused on identifying oil floating on the surface and cleaning it up.

But the real story actually was below the surface.

Contrary to early reports that most of the oil was evaporating, scientists maintain that the pounding surf, gusting winds and relentless tides on Moonstone Beach drove the majority of the oil out of sight beneath the surface of Block Island Sound.

The weather created an immense "bolus" or "blob" of oiled water that slipped back and forth along the shore, completely out of sight. Scientists estimate that at one point it covered an area of 8 square miles, or much bigger.

No one could see it, and only a series of intricate tests will show its exact size and toxicity.

But it is clear that the blob slipped under oil booms and contaminated all of Point Judith Pond.

It apparently killed thousands of lobsters.

It reached nearly every one of the remaining salt ponds along the south shore.

There's no way to clean it up. There's nothing anyone can do with it, except wait for it to deteriorate and disperse, a process that should take two to three weeks.

Now there's something of a chemical detective mystery going on, as scientists anxiously await the laboratory analyses of hundreds of water samples that will tell them how poisonous the blob is, and when it will finally be gone.

Yet most experts agree that the oil will be largely gone well before the summer tourist season. And while the long-term environmental effects of the spill are still uncertain, scientists are relieved with the barge removed, no more oil is leaking into the Sound and the toxicity of the remaining oil is decreasing rapidly.

THE NO. 2 HOME heating oil that gushed from the North Cape is much more similar to gasoline than the heavy crude that spilled from the Exxon Valdez in Alaska.

"We are debating around here whether any good chemist could find any trace of oil out there two months from now," says Kenneth R. Hinga, a chemist and the assistant dean of the University of Rhode Island's Graduate School of Oceanography. "The spill will be a blip in the history of all the other hydrocarbons that are out there."

Hinga should know. Twenty years ago, as a graduate student at URI, he worked with a team of scientists who did major research on how No. 2 heating oil would affect life in Narragansett Bay during a spill.

The Environmental Protection Agency paid for the research and for URI's Marine Ecological Research Laboratory, which consisted of tanker-truck sized tanks at the edge of Narragansett Bay that were pumped full of sea water and marinelife for real-life tests on the effects of oil and othr hazardous wastes.

Four scientists supervised the experiments. Stephen Olsen, Michael E.Q. Pilson and Candace Oviatt are still at URI. Juanita N. Gearing is a chemistry professor at the University of Massachusetts in Dartmouth. All had good reason to look on the North Cape spill with special interest.

"People here study oil spills all the time," said Hinga. "We just have one in smelling range this time."

Based on that early research, and their observations of the North Cape spill site, Hinga estimated that the blob of underwater oil was 4 miles wide and ran 2 miles out to sea. Pilson figured it was much larger.

Even Gearing, working in Massachusetts, immediately appreciated the consquences of the spill.

"There was a lot of wave action and that means probably a lot of the oil went into the water column and down to the sediments," she said early in the week.

ON MONDAY, Hinga demonstrated in front of a television news camera what would happen. He poured oil onto a container of water and watched it float on the surface. Then he lowered the whirling blades of a kitchen mixer into the water, which churned into a murky froth.

Some of the URI scientists attended the "science meetings," held each day after the spill by scientists from the National Oceanic and Atmospheric Administration. The goal was to collaborate with oil spill experts to properly assess the damages.

The insurance underwriter for Eklof Marine, owner of the tug and barge, attended the sessions and approved or rejected paying for various proposals.

The URI scientists quickly became frustrated because there was little official interest in sampling water near the spill.

The Coast Guard and its science advisers and the NOAA continued to give daily updates on where the visible oil was going. They described efforts to skim the oil or to keep it out of the fragile coastal ponds with booms.

"The problem with them was they were focusing on the surface slick," said Malcolm L. Spaulding, chairman of URI's Department of Ocean Engineering, who prepared numerous computerized projections of the oil's fate.

"They kept focusing on these little sheens drifting in Block Island Sound. While they were looking like a problem, there was nothing anyone could do about them. For damages, they should have been looking at the water column," said Spaulding.

BY MIDWEEK, however, attitudes changed.

On Wednesday, NOAA diverted its 187-foot research vessel, the Albatross, from a cruise to Georges Bank to Rhode Island to collect water samples throughout the polluted area, from top to bottom. Eleven scientists were on board.

The same day, NOAA issued a graphic representation showing its latest conclusions about the fate of the spilled oil. The graphic suggested that only about 10 percent of the initial release of 700,000 gallons evaporated; some 80 percent was dispersed in the ocean.

Of a subsequent release of 128,000 gallons or so, maybe 30 percent evaporated, according to the NOAA. About 60 percent was dispersed in the ocean.

The huge lobster die-off last Saturday showed that signficant amounts of oil reached the ocean bottom. As the days went on, more proof came in.

Christopher Kincaid, an assistant professor of oceanography at URI, dragged a device through Point Judith Pond that recorded the presence of oil. It found oil throughout the pond, at every depth.

Virginia Lee of URI's Coastal Resources Center, accompanied EPA technicians on a tour in which they took water samples of the coastal ponds. She, too, came back concerned.

"There's definitely oil in Point Judith, Cards Pond, Potter, Trustom and Ninigret."

ONCE IT WAS known that the oil was everywhere, the critical question became: how much?

Scientists have long known that even without a spill, there's already plenty of oil in coastal waters.

The fishing fleet and recreational boats release significant amounts of oil into Point Judith Pond. One study found that 1,789 tons of various oils flow into upper Narragansett Bay every year -- mostly from rivers and streams and sewer plants.

But the expected background levels in the pristine coastal ponds, far away from heavy industry and municipal sewer plants, was expected to be no more than one part per billion.

Obviously the spill created much higher oil concentrations because dead lobsters kept washing ashore. (Some fishermen say that lobsters are attracted to oil, so they followed their senses to their own deaths.)

But the results of the earliest tests, which came out late in the week, were cause for some optimism.

The EPA released results from Point Judith Pond showing oil concentrations hovering around one part per million.

NOAA scientists said it looked like the average concentrations offshore were about one part per million, as well.

The numbers raised more questions.

NOAA scientists said that this concentration of oil, while 1,000 times greater than the typical level of oil, was not enough to kill most forms of marine life.

Even as the first test results came in, however, thousands more lobsters washed up on the beaches. And that raised more concerns.

Lee said she feared the oil would remain the longest in the salt ponds because it would cling to the fine silts on the bottom. Some of the qualities that make the salt ponds such productive fish nurseries -- calm, nutrient-rich waters -- also would help retain the oil.

"It's going to be a week or two while it's still toxic," she said. "So we could lose the entire food chain. It may kill everything."

The good news, she said, is that the period of worst toxicity should be over and the ponds would have time to rejuvenate before the heavy migrations of birds and fish this spring.

WHEN THE North Cape began spilling oil, many observers made comparisons to the wreck of the World Prodigy on June 23, 1989. The oil was much the same.

But there were some key differences. The Prodigy went aground at the mouth of Narragansett Bay in summer, when varying temperatures within the Bay created layers of water that kept the Prodigy's oil from sinking to the bottom. The calm seas also helped the oil remain on the surface.

Because it was summer, much more marine life was in the Bay so more was at risk.

But at the same time, the Prodigy's oil was broken down much faster by evaporation and bacteria and was quickly dispersed from the Bay.

Wildlife experts collected only about 800 dead lobsters and crabs at Mackerel and Hull Coves in Jamestown after the Prodigy spill.

(The NOAA said scientists have found the Prodigy's oil in the sand at Hull Cove several years after the spill. And scientists are still finding residues of a 1969 oil spill in sediments along the shoreline of West Falmouth, Mass.)

The work of the URI researchers 20 years ago helped show why the Prodigy spill turned out different from the North Cape.

The study found that when the water was warm, bacteria rapidly consumed the oil. But when it was cold, bacteria destroyed little of the oil.

DAVID V.D. BORDEN, associate DEM director in charge of fish and wildlife, attended most of the science meetings and agrees that little attention was paid to the submerged oil in the first days after the spill.

"From my own perspective they weren't focusing on it. It was easier to focus on the visual aspects of the spill."

But Borden said that by midweek, at least 18 different scientific investigations had been launched.

Scientists from NOAA are focusing on the trajectory of the oil spill, fish surveys, and sampling sediments and water in Block Island Sound. The DEM is studying the strandings of lobsters and surf clams and the status of winter flounder larva in the salt ponds. URI biologist Stanley Cobb will study the effects on the reproductive rates of lobsters. The Department of Interior is studying water and sediments in the ponds and bird counts.

During the next few days, local scientists expect to see a multitude of test results that will paint a far clearer picture of the extent of the underwater oil blob and the concentrations of oil within it.

The results also should indicate the potential for long-term environmental damage, such as whether the thousands of dead lobsters will remain the most dramatic victims of the spill. Or they could pinpoint other losses to come.

On Friday, Joseph T. Dealteris, a URI fisheries professor, was back out taking water samples and trawling for fish on the Sound.

He was probably the first scientist on the scene after the spill. Last Sunday he collected water samples from next to the grounded barge to as far as 5 miles out.

The difference between early in the week and Friday was remarkable, Dealteris said.

"I think the bolus of oil was there right after storm. It was evident as late as Tuesday, but as the stuff continues to break down and disperse. We couldn't find it in the water or surface water.

"We found no visible evidence of oil in the water," Dealteris said after his Friday sampling. "And we have yet to see a dead animal. All the fish looked perfectly happy. That's good news."