Deepwater Horizon Oil spill: no crude joke ten years on

The 2010 Deepwater Horizon oil rig disaster which resulted in the deaths of 11 workers and spilled almost 800 million litres of oil into the Gulf of Mexico, has faded somewhat from our conscience, and most of the clean-up work is finished. But new research shows oil remains in the environment for many years.

The spill was the worst environmental disaster in U.S. history, and in addition to the human and economic toll, resulted in the subsequent deaths and long-term health effects of countless birds, shellfish, marine animals and reefs.

Although the majority of the oil was transformed through many natural environmental chemical reactions over the course of the year, a new study in Frontiers in Marine Science reports that small amounts of residue from the spill were still present in the area ten years later.

The study looked deeper into the different components of crude oil,  which is a complex mixture of many different chemicals, and focussed on those which were most highly concentrated and those with the highest toxicity. They then followed the specific chemicals over the next decade, examining any reactions with the environment (resulting in new chemicals and compounds) and measuring their overall persistence.

Much of the spilled oil (around 30-40%) evaporated into air, whilst some chemicals dissolved into the water and were broken down by marine organisms. Some parts of the oil chemically reacted when exposed to the Sun’s ultraviolet light and yet other parts were directly degraded by microbes. Some of the chemicals, however, coated shorelines or sank to the seafloor, detectable even after ten years.

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First author of the report, Professor Edward Overton of Louisiana State University, says: “The better we understand the chemicals and their reactive and physical properties, the better we will be able to mitigate oil spills and understand and detect environmental damage.”

Responding to future oil spills remains a slippery challenge though, with chemical additives, local conditions and weather changing the impact of exposure of local wildlife.

Writing in The Conversation in April 2020, Professor David Uhlmann, Director of the Environmental Law and Policy Program, University of Michigan said after a dreadful start, BP and its drilling partners removed most of the oil from Gulf coast beaches over the next several years.

“The visible sheen of the oil slick eventually disappeared as well. But studies indicate that it will take parts of the Gulf, such as deep ocean ecosystems, decades to recover. We may never know the full extent of the ecological damage.

“BP paid dearly for the reckless corporate culture of cost-cutting and excessive risk-taking that caused the spill: more than US$60 billion in criminal and civil penalties, natural resource damages, economic claims and cleanup costs. Indeed, from a legal standpoint, the legacy of the Gulf oil spill is the sheer size of the payout, which ushered in an era of multibillion dollar criminal and civil penalties for environmental and other corporate crimes.”