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A huge oil spill in California is killing wildlife and threatening protected sites. Cleanup is underway, but officials have warned of "environmental catastrophe." How can we minimize ecological disaster from oil spills?
As dead birds and fish begin washing up on fouled beaches south of Los Angeles, cleanup teams are scrambling to contain one of California's worst oil spills in decades.
A major leak over the weekend from an offshore oil platform owned by Houston-based crude oil producer Amplify Energy Corp has released up to 126,000 gallons (572,800 liters) of heavy crude along a 15-mile (24-kilometer) stretch of coastline, threatening a protected marshland and the commercial and local fishing industries.
Beaches could remain closed for weeks or even months, warned Huntington Beach Mayor Kim Carr.
A ship's anchor, which may have hooked and torn an underwater pipeline, is believed to be responsible for the disaster. Investigators have also said the pipeline owner didn't shut down operations and notify authorities for more than six hours, further slowing the emergency response.
Officials have deployed more than a mile of protective booms in an effort to contain and slow the oil flows. The US Coast Guard, which is coordinating the response, said about 4,788 gallons had been recovered as of Tuesday.
The method for tackling oil spills depends on several factors, including the type and amount of oil in question, location and weather conditions.
"Once the oil comes to shore, the more intensive the cleaning technique. You can risk causing further damage," said Nicky Cariglia, an independent consultant at Marittima, who specializes in marine pollution. "If you wanted to remove all traces of oil, the techniques available become increasingly aggressive the less oil that remains."
Because oil normally has a lower density than water, it floats on the surface of the ocean. This means that for cleanup action to be most effective, it should happen very quickly after a spill, before the oil disperses.
One method of controlling oil spills at sea, which was used after the Grande America cargo vessel sank in March 2019 some 300 kilometers (186 miles) off the French coast, is essentially scooping up the oil from the water's surface.
This is done using booms, which act like a barrier to prevent the oil from spreading. Once it's contained, boats equipped with so-called skimmer machines can suck up the oil and separate it from the water. After being processed, the oil can even be reused.
Booms were used to prevent oil from spreading after the Grande America cargo ship burned and sank in the Bay of Biscay
It seems like a simple method, but it only works when the oil stays in one place — and under the right conditions. When that's the case, the specialized vessels needed for the process can also make this an expensive and logistically challenging method.
In certain conditions, burning the oil off the water's surface can be the most appropriate method. In Arctic or ice-covered waters, for example, it might be the only option.
In-situ burning (ISB) would also be used to tackle an uncontrolled oil leak, where a lot of oil is spilling fast. When the Deepwater Horizon offshore oil rig caught fire and sank in April 2010, oil gushed from the seabed and caused the largest accidental oil spill in history. ISB proved to be a highly effective technique in responding to the disaster.
Controlled fires burned off oil spilled in the Gulf of Mexico after the Deepwater Horizon disaster in 2010
But the method also produces toxic fumes which can have a negative impact on the environment. And it comes with challenges, too. "It can be difficult to herd enough oil to make it thick enough to burn," said Cariglia. "If the oil had dispersed over many days, it would not be an option."
Absorbents can be kinder to the environment: They act like a sponge to soak up the spilled oil. But they're more useful for clearing small amounts of oil on land and are not usually effective in tackling a spill out at sea. In fact, employing these materials on the water can create further pollution.
"Recovering and disposing of these oiled materials requires a lot of energy," said Cariglia. "There's a risk that oiled debris will get lost at sea."
Experts also disagree over the effectiveness of different absorbent materials, which can range from natural products such as straw to highly engineered synthetics developed by scientists for the purpose of tackling oil spills.
In January 2016, firefighters used absorbents to clean oil leaking from a sinking cruise ship in the Han River in Seoul
In recent years, sustainable solutions have also been introduced. After a Japanese-owned oil tanker struck a reef off Mauritius on July 25, 2020 and leaked more than 1,000 tons of fuel into the Indian Ocean, hundreds of local volunteers made buoys filled with sugar cane pulp and placed them in the water "to try to absorb and contain the oil which had already spread in our lagoons," blogger Ish Sookun wrote in a post on August 8.
Human hair, which is said to be a superior oil absorber, was also added to the mix, with locals donating their locks to fill the handmade booms. Hair is a lipophilic material, meaning it repels water but is excellent when it comes to absorbing oil.
A study published by the University of Technology Sydney (UTS) just weeks before the Mauritius disaster found that booms made of hair and dog fur "were significantly better at absorbing crude oil from simulated oceanic spills compared to mainstream commercial sorbents including polypropylene, recycled cellulose, and cotton by-products."
This method has also been used to help clean up other major oil spills, including the 2007 Cosco Busan disaster off the coast of California and the 2010 Deepwater Horizon disaster in the Gulf of Mexico. Environmental groups in countries like the United States, United Kingdom and Australia have mobilized to collect hair clippings from salons and turn them into sustainable cleanup solutions.
Cariglia, however, is wary of solutions purporting to suck up slicks. "It's not that they don't work," she said. "In lab experiments, they can work very well. But in real life, the oil has spread at sea."
When the area of the oil spill is difficult to reach or very far out to sea, nature itself can help tackle the issue. Wind and waves will naturally disperse the oil over time, parts of it will evaporate and naturally occurring microbes will also do their work to start breaking down the oil.
But this is a slow and unreliable process that needs to be closely monitored and "should not be confused with 'sitting down and doing nothing,'" according to Marine Insight, a maritime industry information site.
Chemical agents can also be used to aid this process, and Cariglia is keen to allay environmental fears. "Toxicity tests are designed so that the only things that are approved are milder than the soap you would use at home," she told DW.
Though the dispersants themselves are not toxic, environmental problems can occur when they are used in sheltered or shallow locations. In that situation, using dispersants can mean that the oil spreads around more of the delicate marine environment. "For example, in locations where there are coral reefs, it would be better if the oil stayed on the surface," said Cariglia.
But when it comes to tackling oil spills, she added, "there is no single miracle cure."
This is an updated version of a previous article originally published on March 28, 2019. Stuart Braun and Martin Kuebler contributed to this report.