Spill repeats itself

With the 1989 Exxon leak still trickling oil, the Gulf of Mexico puts scientists in the worst fix  

 
By Manupriya
Published: Saturday 04 July 2015

imageDEEPWATER horizon, the giant drilling rig in the Gulf of Mexico, exploded off the US coast of Louisiana on April 20.

The rig, leased to British Petroleum (BP), sank leading to an oil spill that is now the worst in US history surpassing even the 1989 Exxon Valdez disaster. Six week-long efforts costing BP over US $750 million have failed to contain the spread of oil. Nearly 161 km of coastline has been affected. With thousands of barrels of oil pouring into the waters everyday, scientists fear the worst—the oil has headed straight for the Gulf marshes threatening the lives of over 90 per cent bird and fish species.

BP has been laying hundreds of hard booms to save cleaner waters. Booms are long inflatable pillows stuck to each other and have skirts hanging under the surface. They can cut off the shore from the slick if the spill is at the ocean surface. In case of the Gulf they are proving ineffective. With the well belching out oil from the ocean bed, the entire water column is polluted.

BP has tried to skim off and burn the oil in its efforts at recovery. The US Environmental Protection Agency has even allowed the company to use dispersants— soap-like substances that make the oil degradable naturally. Three trials on underwater dispersants by BP have proved inconclusive so far. Studies, however, show that dispersants harm the environment in the long run. The Exxon Valdez spill is an example of remediation that went wrong.

Researchers found that lack of funds proved a blessing for areas untouched by those chemicals in the Exxon spill; the other areas are still affected (see The persistent reminder). BP has not had success in its efforts yet but scientists are trying several courses of action to get out of this fix. Environment scientists say soaking up the oil is the best option yet. Natural fibres like bagasse, hay, straw and human hair act as good absorbents.

Scientists have also developed certain oil-absorbing aerogels. David Schiraldi’s project Aeroclay at the Case School of Engineering in USA is an ultra-light sponge made of 96 per cent air, 2 per cent polymer and 2 per cent clay. The interesting part is the oil absorbed by this oil-loving, water-hating aerogel can be squeezed out and reused.

“The best methods for cleanup, I think, are those that are environmentally and economically effective,” said Thomas Azwell, from the University of California in Berkeley. “I use natural fibres to collect the oil, brew microbial inoculants to emulsify it and make it bioavailable, then blend it with food waste and animal manure and feed the compost to earthworms. The end product is nutrient-rich worm castings,” he added.

LEAKAGE ESTIMATION FAILS

Top kill—British Petroleum’s (BP) ambitious method to plug the leaking oil well with mud and debris— has failed. BP has been unable to estimate the rate of leakage. In an article published in Nature on May 23, marine scientist David Valentine from the California University said, “Estimates have ranged from 1,000 to 100,000 barrels per day with little detail on the methods.” He suggested a good way would be to measure the amount of methane emanating from the spill. A University of Miami team in USA has developed a model for locating sunken oil following spills.

THE PERSISTENT REMINDER

It is estimated the amount of oil spilt by Exxon Valdez at Prince William Sound in Alaska in 1989 could fill 125 Olympic-sized swimming pools. Published online on January 21 in Environmental Toxicology and Chemistry, a study reveals generations of Harlequin ducks still display high levels of EROD (7-Ethoxyresorufin-O-deethylase) activity which is a measure of contaminant exposure. Another study out in Nature Geosciences on January 17, said: “Oil persists in the subsurface gravel beaches.” Remediation of beaches ended in 1992 on the conjecture that the oil would disappear on its own.

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