Oil from the 1989 Exxon Valdez tanker spill that devastated Alaska’s Prince William Sound still lies trapped beneath its beaches, continuing to pollute once pristine shores, scientists reported yesterday.
As climate change opens the Arctic region to oil exploration and shipping, the findings could prove crucial in devising effective methods for cleaning up future spills, the researchers said.
Up to now, experts puzzled over why remnants of the 11 million gallons (41.6 million liters) of crude that fouled some 1,300km of Alaskan coastline have persisted for so long.
At first it seemed that nature, with some help from technology, would soon wash away one of the worst environmental disasters in history.
The spill decimated the region’s wildlife as well as the state’s fishing industry.
But within a decade it became apparent that the rate at which the oil was disappearing had dramatically slowed, from 70 percent per year to about 4 percent.
Today, it is estimated that some 20,000 gallons remain.
Michael Boufadel and Li Hailong of Temple University in Philadelphia, Pennsylvania wanted to find out why this oil was not been broken down through biodegradation and weathering, as had been widely predicted.
Collecting field data and running computer simulations, they found the key lay in the fact that affected beaches consisted of two layers, each with different properties.
The geographically variable impact of rising and falling water tables also played a critical role.
Oil was temporarily stored in the porous upper layer, slowing the rate at which it was subject to weathering, according to the study, published in the journal Nature Geoscience.
An environment lacking the kind of nutrients needed by oil-eating micro-organisms to thrive further protected the fossil fuel.
The second layer, while composed largely of the same materials, was far less porous: on average, water moved through the top layer 1,000 times faster.
When the water level from declining tides fell below the interface between the two layers, oil seeped from the upper to the lower stratum, especially where there was little or no freshwater discharge to compensate.
“Once the oil entered the lower layer, it became entrapped by capillary forces and persisted,” the authors said.
Because of the even lower oxygen content in the sub-stratum, the crude was not degraded and has remained suspended.
The study also said that oil tends to linger on gravel beaches more than on sandy ones, pointing to evidence from previous spills: the Arrow in Nova Scotia, Canada (1970), the Metula in the Strait of Magellan, Chile (1974), and the Amoco Cadiz along the French coast of Brittany (1978).
“As global warming is melting the ice cover and exposing the Arctic to oil exploration and shipping through sea routes such as the Northwest Passage, the risk of oil spills on gravel beaches in high-latitude regions will be increased,” it said.
‘BARBAROUS ACTS’: The captain of the fishing vessel said that people in checkered clothes beat them with iron bars and that he fell unconscious for about an hour Ten Vietnamese fishers were violently robbed in the South China Sea, state media reported yesterday, with an official saying the attackers came from Chinese-flagged vessels. The men were reportedly beaten with iron bars and robbed of thousands of dollars of fish and equipment on Sunday off the Paracel Islands (Xisha Islands, 西沙群島), which Taiwan claims, as do Vietnam, China, Brunei, Malaysia and the Philippines. Vietnamese media did not identify the nationalities of the attackers, but Phung Ba Vuong, an official in central Quang Ngai province, told reporters: “They were Chinese, [the boats had] Chinese flags.” Four of the 10-man Vietnamese crew were rushed
STICKING TO DEFENSE: Despite the screening of videos in which they appeared, one of the defendants said they had no memory of the event A court trying a Frenchman charged with drugging his wife and enlisting dozens of strangers to rape her screened videos of the abuse to the public on Friday, to challenge several codefendants who denied knowing she was unconscious during their actions. The judge in the southern city of Avignon had nine videos and several photographs of the abuse of Gisele Pelicot shown in the courtroom and an adjoining public chamber, involving seven of the 50 men accused alongside her husband. Present in the courtroom herself, Gisele Pelicot looked at her telephone during the hour and a half of screenings, while her ex-husband
Scientists yesterday announced a milestone in neurobiological research with the mapping of the entire brain of an adult fruit fly, a feat that might provide insight into the brains of other organisms and even people. The research detailed more than 50 million connections between more than 139,000 neurons — brain nerve cells — in the insect, a species whose scientific name is Drosophila melanogaster and is often used in neurobiological studies. The research sought to decipher how brains are wired and the signals underlying healthy brain functions. It could also pave the way for mapping the brains of other species. “You might
PROTESTS: A crowd near Congress waved placards that read: ‘How can we have freedom without education?’ and: ‘No peace for the government’ Argentine President Javier Milei has made good on threats to veto proposed increases to university funding, with the measure made official early yesterday after a day of major student-led protests. Thousands of people joined the demonstration on Wednesday in defense of the country’s public university system — the second large-scale protest in six months on the issue. The law, which would have guaranteed funding for universities, was criticized by Milei, a self-professed “anarcho-capitalist” who came to power vowing to take a figurative chainsaw to public spending to tame chronically high inflation and eliminate the deficit. A huge crowd packed a square outside Congress
RSS