Dispersant chemicals 'worsened Deepwater Horizon spill' in Gulf Coast
Dispersant chemicals used by the British Petroleum in response to the Deepwater Horizon spill may have made oil sink deeper and faster into the US Gulf Coast beaches, scientists have claimed.
The research paper has warned that toxic components of the light crude may even have penetrated as far as groundwater supplies due to chemicals.
After the 2010 blowout at the Macondo Prospect, the company released about 2.6 million gallons of dispersant chemicals to disperse the huge quantities of crude oil spilling into the Gulf of Mexico.
Dispersing the oil had short-term effect of making the catastrophe look less severe, but little was known about the long-term environmental effects.
Scientists said that the chemical may have simply made toxic components of the crude more mobile, allowing them to further penetrate beach sediments and leak back into the water where they could harm marine life.
Researchers from Utrecht University in the Netherlands and Florida State University examined the effects of the Corexit 9500A - a chemical dispersant BP pumped into surface waters and at the wellhead in response to the spill.
They found that using Corexit 9500A has the unexpected effect of allowing potentially harmful crude oil components called polycyclic aromatic hydrocarbons to penetrate deeper and faster into the sands.
Once there the lack of oxygen could slow the degradation of the PHAs, extending their lifespan.
The researchers warned that using such dispersants in oil spills near shore could allow these chemicals to penetrate sands deeply enough to threaten groundwater supplies.
The researchers said that the application of the dispersant chemicals changed the behaviour of the oil when it hit the gulf coast's beaches in three ways.
Firstly, it transformed the oil into tiny particles that were better able to permeate through the sand.
Secondly, it coated these particles in such a way that they were less likely to stick to sand grains.
And lastly, it coated the sand grains themselves, making them less able to hold on to the oil.
The study has been published in the open-access journal PLOS ONE.