Gulf oil threatens ecology, maybe climate.
On or about Jan. 20, five oil supertankers berthed at the Kuwaiti port of Mina al Ahmadi began discharging an estimated 3 million barrels of crude oil into the Persian Gulf. At about the same time, an underwater pipeline carrying crude oil from storage tanks there to Sea Island, a tanker-loading terminal about 10 miles offshore, also began spewing oil into the Gulf.
U.S. Defense Department officials say "precision munitions" fired on Jan. 26 from an allied aircraft apparently halted the flow from the pipeline by sealing off its inlet pipes -- but not before it had pumped out an estimated 7 to 8 million barrels of oil.
The two releases created the largest oil spill in history, sending a total of 10 to 11 million barrels of crude into the Gulf's shallow and relatively contained waters.
Though Iraqi President Saddam Hussein denies his forces caused the spill, governments allied against Iraq have condemned him for what they call an act of "environmental terrorism." Many scientists worry that the spreading slick threatens unprecedented damage to the ecology of the Persian Gulf.
Jeffrey Hyland of the Marine Science Institute at the University of California, Santa Barbara, says the best available estimates of global inputs of oil suggest that about 23.4 million barrels of oil enter the world's oceans each year from all sources. Using those estimates, Hyland calculates that this one slick may represent up to 47 percent of the oil ordinarily spilled globally in a year -- "an incredible amount," he says. The spill contains more than 40 times the amount of oil released off Alaska two years ago by the Exxon Valdez supertanker.
The Persian Gulf spill was not unexpected, according to a report completed Jan. 9 by Sandia National Laboratories. Leaked summaries of this now-classified document warned that Iraq might attempt to pump as many as 20 million barrels of oil into the Gulf. The report, titled "Potential Impacts of Iraqi Use of Oil as a Defensive Weapon," also speculated that Saddam might set Kuwaiti oil fields afire, potentially initiating "measurable climatic effects on a regional level."
Environmental scientists have begun speculating on the spill's potential for wreaking long-term havoc.
Unlike the Valdez oil, Kuwait's crude is "light," says petroleum chemist Mahlon C. Kennicutt of Texas A&M University in College Station. In other words, he says, it contains more of the volatile aromatic compounds -- "known to be toxic" -- and less of the much heavier and relatively nontoxic hydrocarbons. "In that sense," Kennicutt says, "the Kuwaiti oil, weight for weight, would be more toxic than the Valdez crude."
On the other hand, the volatile fractions of the Kuwaiti oil evaporate quickly, he notes, and light oils leave less residue. Up to 50 percent of a Valdez-type crude may remain even after substantial "weathering" (photochemical breakdown and the loss of volatiles to the air and water), Kennicutt says, but with a Kuwaiti-type oil, "I would be surprised if more than 10 percent remained" to contaminate beaches and sediments.
Unfortunately, weathering may not detoxify all the surviving oil. As sticky, weathered residues form tar balls -- which sink into sediments -- they may encapsulate unweathered oil. If wave action later erodes these balls, the toxic unweathered oil may seep out to threaten coastal and sediment-dwelling organisms, Kennicutt notes.
A 1986 spill on the Caribbean coast of Panama, involving 50,000 barrels of oil, probably offers the most recent and applicable parallel to the Gulf disaster, according to oil-spill expert Edward S. Van Vleet at the University of South Florida in St. Petersburg and Kathryn A. Burns of the Bermuda Biological Station. Burns, who has studied oil pollution in the Mideast and Panama, notes that both areas are warm and very sunny, and that their shallow waters nurture related, sensitive ecosystems: coral reefs, mangrove forests and coastal seagrasses.
Burns says her studies suggest that although rapid weathering may remove the Gulf's surface slick fairly quickly -- in weeks -- sediment-dwelling organisms in the area may suffer ecological impacts for years. In Panama, she notes, the initial oiling not only killed corals, mangroves and intertidal seagrasses but also wiped out many organisms dependent upon these ecosystems.
Michael Marshall, who studied seagrasses at the Panama site, says sea urchins, starfishes and shrimp-like amphipods had failed to return to subtidal seagrass beds even after three years had passed. In the Persian Gulf, nine species of subtidal and intertidal seagrasses -- and the animals that live among them -- could prove similarly vulnerable to oil, says Marshall, a biologist with Continental Shelf Associates in Jupiter, Fla.
"Having studied oil spills in temperate zones, I thought oil would degrade fairly rapidly in this water," Burns says. "But in Panama we're still seeing high levels of oil in sediments even after five years." The oil appears to be leaching into water, she says, and that may explain why some aquatic species have been so slow to return.
Most researchers don't expect much from spill cleanup efforts. However, several nations have dispatched experts -- including specialists in the use of dispersants and microbial oil scavengers -- to assist the Saudis, who will manage containment operations.
Kuwaiti oil also left its mark in the air last month, as fires on parts of the spill, coupled with oil fires in Kuwait, sent black smoke billowing into the atmosphere. While those blazes remained relatively small, scientists are debating the possible environmental effects of the huge conflagrations that could erupt if Iraq decided to burn hundreds of Kuwaiti oil wells in an act of desperation.
As a worst-case scenario, some researchers suggest that smoke from such fires could reduce rainfall over southeast Asia and could even cause unseasonal frosts as far away as the United States. Others deny the possibility of far-flung impacts, saying the fires could only affect regions close to Kuwait.
At a meeting in London last month, Richard P. Turco of the University of California, Los Angeles, assessed the potential for large-scale hemispheric effects. He and astronomer Carl Sagan of Cornell University have calculated that major fires in the Kuwaiti fields could burn several million barrels of oil daily, sending 50,000 tons of soot into the atmosphere each day for months. While the smoke would initially rise no higher than 1 or 2 kilometers, the black soot particles would absorb sunlight and could eventually move up to the middle troposphere, from which they would travel east with the prevailing winds. If the soot reached such altitudes, the region's dry climate could keep it in the atmosphere for several weeks.
To gauge the possible impact of such a cloud, Turco turns to the 1815 volcanic eruption of Tambora in Indonesia. Although volcanoes produce a very different type of cloud, the oil fires could lead to a comparable reduction in solar radiation over a vast portion of the Northern Hemisphere, Turco told SCIENCE NEWS. In the year following Tambora's eruption, parts of the United States and Europe suffered unseasonal crop-killing frosts, and Turco suggests a similar effect might accompany fires in Kuwait.
John Cox, an engineer who consults on safety at Persian Gulf oil installations, suggests another chilling scenario: The smoke cloud from more than 300 burning oil wells could cool India enough to prevent the summer monsoonal rainfall. The resulting crop failure would place hundreds of millions of people in jeopardy of starvation, he told scientists at the January meeting.
A particularly inconclusive report from the British Meteorological Office in Bracknell, based on computer simulations of oil-fire smoke, plays down these potential effects while not discounting them entirely. The report, issued Jan. 17, states: "Downwind of Kuwait, the obscuration of sunlight might significantly reduce the surface temperature locally. This in turn could locally reduce the rainfall over parts of southeast Asia during the period of the summer monsoon."
A relatively optimistic analysis comes from U.S. researchers who have run computer simulations of their own. Michael C. MacCracken of Lawrence Livermore (Calif.) National Laboratory found that the soot would have limited climate effects because it should fall out of the atmosphere much sooner than Turco and Sagan have suggested. MacCracken estimates the plume would rise less than 5 kilometers; from this value, the computer calculates that soot would stay in the atmosphere at most nine days.
Richard Small, a fire-effects expert at the Pacific-Sierra Research Corp. in Los Angeles, projects even shorter smoke plumes. In his computer simulations, the clouds from well fires rise only 1 kilometer, says Small, who reported these results to the Defense Department in early January. "While there's a very large amount of smoke, it's not large enough to have climate effects," he told SCIENCE NEWS. By the time the smoke reached India, it would reduce solar radiation by only 5 percent -- not enough to significantly affect rainfall there, he says.
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|Title Annotation:||Persian Gulf oil spill|
|Date:||Feb 2, 1991|
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