Oil dispersants an environmental ‘crapshoot’

May 24, 2010 by  
Filed under Toxic Spills

by Kari Huus
updated 5/24/2010 5:49:57 PM ET

The timing could not be worse for the bluefin tuna. The majestic, deepwater giant — threatened by overfishing — had just lost a bid for protection as an endangered species when oil started gushing into its spawning grounds in the Gulf of Mexico. Now, a part of the emergency response to the oil — the large-scale use of dispersants — could further imperil the species by sinking the oil beneath the Gulf’s surface and into the zone where its eggs and larvae are floating, marine biologists say.

The chemical dispersants — a standard tool in the oil cleanup business — are being used by the Deepwater Horizon response team to break up the oil offshore in hopes of preventing thick crude from wrecking delicate marshlands, mangroves and pristine beaches.

The federal government — the National Oceanic and Atmospheric Administration, the Environmental Protection Agency, the U.S. Coast Guard and other agencies — has signed off on BP’s use dispersants as a necessary part of the company’s damage-control strategy in the wake of the April 20 accident aboard the Deepwater Horizon drilling rig.

But the chemicals, which are being used in unprecedented volumes and in previously untested ways, may come with a big tradeoff, scientists say. That’s because no one can accurately predict how large the impact will be on the mammals, fish and turtles that inhabit the open ocean.

“It’s a whole new ball game,” said Ted Van Vleet, a professor of chemical oceanography in the college of Marine Science at the University of South Florida. “People are totally unsure as to how it is going to affect the ecosystems.”

Dispersants themselves are toxic. But a bigger concern in the scientific community is what happens in dispersing the oil, which is far more hazardous to living creatures.

Typically, dispersant is sprayed on the surface of the water, where the oil naturally comes to rest, and works a bit like a dishwashing detergent on grease. It breaks down the slick into millions of tiny oil droplets that then become suspended below the surface, normally in the top 30 to 50 feet of the ocean. There, over the course of weeks and months, oil-eating bacteria, sunlight and wave action help break the oil downinto its chemical components, which are then diluted throughout the water.

But in the interim, the oil droplets drift in the upper layer of water, where many sea creatures live and reproduce.

“The fact that (dispersants) remove oil from the surface doesn’t mean it’s not toxic,” said Van Vleet. “It moves oil down into the water column, where other marine animals are exposed to it. … It trades one ecosystem for another.”

Unprecedented, untested
In the Deepwater Horizon accident, the response team has used more than 670,000 gallons of chemical dispersants as of Fridayfar surpassing any previous use in the United States. Most of it has been sprayed from airplanes, but the Deepwater Horizon response team also has applied at least 55,000 gallons in a completely untested way — injecting it at the well’s leaking riser, some 5,000 feet below the surface.

Tag-a-Giant Foundation

Dr. Steve Wilson of Stanford University tags a 700-pound bluefin tuna off Canada with a satellite monitoring tag. The fish was tracked in 2009 as it travelled to the Gulf of Mexico, where the fish spawn, now the site of the Deepwater Horizon oil spill.

While the dispersant may result in fewer oily egrets in the marsh, the bluefin is one of the creatures that may suffer greatly instead. The oil spill area overlaps with only known spawning area for one of two remaining bluefin populations. This bluefin population spends about 10 months of the year in the cold waters of the north Atlantic and then swims thousands of miles to reach an area near the Deepwater Horizon well to disseminate sperm and eggs in the warm Gulf waters between April and June. The larvae float about 10 to 15 feet below the surface in early stages of growth. No one is certain whether the oil will destroy the eggs or kill the larvae, but scientists fear that could happen.

“It is a critical habitat … and this is the most delicate life stage,” said Barbara Block, a professor at Stanford University studies bluefin tagged with sophisticated tracking devices. “The biodiversity of bluefin is at stake right now. … If we lose the year (of new bluefin) it will have a very large impact on a population of bluefin that is on the edge of extinction.”

This is the spawning ground for many other species, including marlin, swordfish and yellowfin tuna, which arrive in the summer.

Some of the chemical components distributed throughout the water will remain toxic for decades, and it’s not clear what the impact could be on future generations of bluefin or other creatures — sperm whales, Bryde’s whales, offshore dolphin populations and seabirds — that fish far from shore.

Monitoring the impact of oil and dispersant chemicals on open-sea fish and other creatures is difficult, experts say, because unlike shorebirds and oysters, they are hard to count.

“It’s hard to see them,” said Lee Crockett, director of U.S. Fisheries policy at the non-profit Pew Charitable Funds environmental group. “If they die, they are on the bottom of the ocean a mile down … For bluefin and marlins, it could be several years before you see what the impact was.”

Deep sea mystery and dead zones
One of the biggest unknowns is how the dispersants might affect the environment near the well head, a mile beneath the surface. BP and the EPA have said that initial monitoring of dispersants suggests the chemicals are helping to break up the crude.

But scientists say the monitoring plan has not been made available for outside review — raising a general complaint about a lack of transparency from the oil company and the government.

And some note that little is known about the deepwater ecosystem — or how the oil and dispersants will react under extremely high water pressure, very low temperatures, limited oxygen and virtually no light. Just getting good samples at this depth is a major challenge.

“There are a bunch of things in the deep sea that we don’t know very much about,” said Ed Overton, professor in the Marine Sciences Department at Louisiana State University. “What happens if those resources are damaged? How does that affect the ecology of the Gulf? It’s a crapshoot … an educated crapshoot.”

The conditions at the bottom of the Gulf also could affect the bacteria that help break down the oil near the surface, as they are less active in cold temperatures than in the warm surface waters, and they may be less abundant in the deep.

“We know that the surface material has been degrading,” says Ralph J. Portier, professor of environmental studies at LSU. “But what about the microbial population at depth?”

Lee CelanoReuters file

Greenpeace staff member Lindsey Allen tests water in a heavily oiled marsh near South Pass, La., on May 19. Despite use of dispersants and thousands of feet of containment booms, some of the slick is beginning to wash up in the delicate coastal ecosystem.

If the oil on the ocean floor is not degraded by bacteria, the danger is that it will remain toxic for much longer than it would near the surface — potentially lingering for years instead of weeks or months — during which time it could be carried to deep coral reefs that provide shelter and nurseries to many species of fish.

There is a debate about the extent to which the Deepwater Horizon oil has entered the Loop Current, a warm flow that moves water — and any contaminants in it — southeast out of the Gulf, through the Florida Straits and into the Atlantic Ocean — potentially threatening the Florida Keys and other sensitive coral reef areas.

The massive use of dispersants in addition to oil may also be further depleting the water of oxygen contributing to “dead zones.”

“All chemicals do this,” said Portier. “If we poured in 400,000 or 500,000 gallons of buttermilk, we’d have a problem with oxygen,” he said.

The other unknown
The dispersant itself, while not the main concern, also is under scrutiny.

BP has used hundreds of thousands of gallons of Corexit, which is produced by Nalco, a Naperville, Ill.-based company.

About a third of the product, which is EPA approved, is a soap-like surfactant that breaks up the oil, according to Van Vleet, the chemical oceanographer. The surfactant is not considered toxic, though some studies suggest it may corrode fish eggs, made up largely of lipids, much as it dissolves oil.

Another third is a petroleum-based “carrier” that facilitates spraying. This component is somewhat toxic to plants and animals — though far less so than crude oil.

The final third of the ingredients are not publicly disclosed because the information is considered proprietary.

Shifting with the tides
On May 15, after some initial testing, the EPA and the Coast Guard approved BP’s use of dispersants at the well head, saying they had collected preliminary data showing it was helping keep some of the oil from reaching the surface.

The same day, however, The New York Times reported that a group of scientists aboard the research vessel Pelican had identified massive plumes of subsea oil — some as big as 10 miles long and 3 miles wide. The article said that scientists on the ship speculated that heavy use of dispersants had contributed to creation of the plumes.

NOAA challenged the report the next day, saying the release of the Pelican team’s data was premature, that the interpretation was misleading and that there was no information connecting subsurface layers of oil with the subsea dispersants.

“NOAA continues to work closely with EPA and the federal response team to monitor the presence of oil and the use of surface and sub-surface dispersants,” said NOAA Administrator Jane Lubchenko. “As we have emphasized, dispersants are not a silver bullet. They are used to move us towards the lesser of two environmental outcomes.”

On Thursday, the EPA issued a statement saying it had ordered BP to begin using a “less toxic” alternative to Corexit within 24 hours, even though the latter product is on a list of EPA-approved dispersants. The directive came a month after the Deepwater accident and after some 600,000 gallons of Corexit dispersants had been applied.

BP continued to spray Corexit on Monday.

“If we can find an alternative that is less toxic and available, we will switch to that product,” said Doug Suttles, BP’s chief operating officer. “To date, we’ve struggled to find an alternative either that had less risk to the environment or that was readily available.”

In an afternoon conference call on Monday, the U.S. government said it had ordered BP to “significantly scale back” its use of chemical dispersants in the oil spill response.

“The federal government, led by the Coast Guard, is today instructing BP to take immediate steps to significantly scale back the overall use of dispersants,” EPA Administrator Lisa Jackson told reporters on a conference call.

“Because of its use in unprecedented volumes and because much is unknown about the underwater use of dispersants, EPA wants to ensure BP is using the least toxic product authorized for use,” the agency said. “We reserve the right to discontinue the use of this dispersant method if any negative impacts on the environment outweigh the benefits.”

This is just one area in which the Deepwater Horizon oil mess has taken responders into uncharted territory.

“The science hasn’t caught up with the situation,” said Overton, the marine scientist from LSU and a member of the scientific support team for NOAA.

© 2010 msnbc.com source: http://www.msnbc.msn.com/id/37282611/ns/gulf_oil_spill/

The Oil Spill’s Effects on Deep-Sea Ecology

May 24, 2010 by  
Filed under Toxic Spills

The Great Unknowns in Gulf Oil Spill

by Ian Yarett
May 24, 2010

The deep water of the ocean is the largest habitat on earth but it’s also the least understood, making the effects of this deep-sea spill without precedent.

The oil spill in the Gulf of Mexico falls into a distinct category from any other oil catastrophe; it’s the first blowout in history to release oil in such deep waters, nearly a mile below the surface.

As a result, scientists say, the impacts of this spill are likely to go far beyond the oiled birds and dead sea turtles, spoiled beaches and wetlands that we think of when we think “oil spill.” A substantial piece of the total impact is likely occurring under the sea, invisible (for now at least) but no less ominous than the more traditional shoreline effects. Far below the sea, the spill threatens organisms of all kinds and, indirectly, the ecosystem at large, though the extent of the danger is still obscured.

Oil on the surface of the ocean is a known quantity, says Ed Overton, an oil-spill expert at the Louisiana State University who is analyzing water, sediment, and other samples for NOAA’s scientific-support team. “It’s going to cause very substantial and noticeable damage—but it won’t take very long to find the marsh loss and coastal erosion and impact on fisheries,” he says. The effects of oil in the water column and at the sea floor, on the other hand, remains a mystery.

The first scientific mission to assess deepwater impacts of the Deepwater Horizon blowout, conducted from the research ship Pelican and funded by NOAA, discovered massive plumes of dispersed oilup to 30 miles long by seven miles wide and hundreds of feet thick. Though the data collected by the Pelican was criticized by NOAA as being too preliminary to draw conclusions from, scientists say the finding is not surprising and is in line with the results of previous studies.

One such study, a 2003 report by the National Research Council, considered what the effects of a deepwater well blowout might be and predicted that such an event, particularly of a reservoir rich in gas (as the Deepwater Horizon reservoir appears to be) would generate diffuse underwater plumes of microaerosolized oil much like what the Pelican scientists found.

A few years earlier, the U.S. Minerals Management Service (MMS) organized a study in 2000 in which scientists released oil into deep seas off the coast of Norway, but could only account for a small amount of it on the surface—suggesting that much of it remained in the water column. (While the conditions of this study aren’t identical to the conditions of the current spill, Overton says the general findings could be expected to apply).

Conventional wisdom suggests that oil is lighter than water and therefore floats, but that’s not entirely the case when a complex mixture of crude oil and natural gas is gushing from a well a mile below the surface, at high temperature and pressure, as is happening right now in the gulf. In this case, the gas can effervesce out of the oil, aerosolizing it into tiny droplets, much the way a fine mist emerges from the top of an aerosol can. Some of these droplets may be neutrally buoyant, meaning they move to a point in the water column where they neither rise nor sink, possibly resulting in underwater “plumes” like the ones reported. Adding subsea dispersants, which similarly break up the oil and are intended to prevent it from reaching the surface, may exacerbate this and could have toxic effects themselves.

A major impact of subsea oil plumes is that they lead to a bloom in oil-chomping microbes. These bugs eat the oil, but use oxygen in the process—meaning that oxygen levels in the water can drop rapidly and threaten the organisms living there. Samantha Joye, one of the principal investigators for the Pelican mission, says her team found that water within the plumes was 30 percent less oxygenated than normal. That’s not enough of a drop to suffocate organisms—but she worries that it could get there relatively soon.

There is plentiful life in the deep sea that’s in danger: fish, deep-sea corals, gelatinous zooplankton like jellyfish, and benthic-dwelling sharks, not to mention the diverse communites of shrimp, crabs, worms, and other critters that live near natural methane seeps. “It’s like a lush jungle down there,” Joye says. Even if oil exposure doesn’t kill these organisms, it could have chronic, long-term effects, like impaired growth or reproduction.

Over time, any impact on the deep-sea communities is likely to have more broad effects, since the whole ocean is connected by various biological processes. “All the different zones of life are interactive in one way or another,” says Lisa Levin, a marine ecologist at the Scripps Institution of Oceanography.

And any oil in the deep-sea environment could persist for a long time. The majority of oil on the surface evaporates, washes up on shore, or is degraded by natural weathering and oil-eating microbes. In the deep sea, on the other hand, it’s dark and still, meaning no weathering and no evaporation. Microbial degradation is pretty much the only mitigating process—but it’s slow. As a result, there’s some possibility that deep-sea oil could get churned up by storms and have a limited shoreline impact sometime in the future, Joye says.

It could take years to find out the extent of the oil’s subsea impact, but the scientists interviewed for this article stressed the importance of beginning the search immediately, even before the gushing well is capped. “If you don’t look you won’t find,” says Rick Steiner, a marine biologist who worked on the Exxon Valdez spill back in 1989. “Hats off to the Pelican for doing what they could out there, but they might have sampled 1 percent or less of the total volume of the impact.” Many other questions about the plumes remain, Joye says, including what’s happening inside them, how are they moving, whether they’re growing or shrinking, and if there are more of them.

It’s also essential to get an accurate measure of the amount of oil being released, as this would allow scientists to deduce how much oil could be hiding below the surface based on the size of the oil slick and estimates of other factors like evaporation.

On these points, the scientific community has been increasingly critical of the official response to the spill, alleging that both the government and BP have resisted entreaties to either investigate the spill’s magnitude and subsea impacts themselves or to allow independent scientists to do so.

“These deepwater effects are not going to mess the beaches up, and they’re not going to have an immediate impact on the shrimp fishery, but they could have long-standing impacts,” Joye says. These hidden impacts—and the way they are handled—could one day be considered the Deepwater Horizon’s legacy.

source: http://www.newsweek.com/2010/05/24/the-great-unkowns-in-gulf-oil-spill.html