© NOAAContinued testing has found evidence of oil in the water, sediments and marine animals of the Gulf nearby the site of the Deepwater Horizon explosion.
It's now been more than three and a half years since the
Deepwater Horizon oil drilling rig leased to BP exploded, causing over 200 million gallons of crude oil to spill into the Gulf of Mexico, the
largest offshore oil spill in U.S. history.
In terms of the national news cycle, that duration might seem like a lifetime. In terms of an ecosystem as enormous and complex as the Gulf, it's more like a blink of an eye.
"Oil doesn't go away for a very long time," says
Dana Wetzel, a biochemist at
Mote Marine Laboratory in Florida who's been sampling water, sediments and the tissues of animals living in the Gulf for evidence of persisting oil. "The assumption had been that in a higher temperature environment, bacteria are going to degrade things much more rapidly, and it'll degrade quicker." But in previous research, she's found that even in warm environments, oil residue persists much longer than experts previously thought - in the waters of Tampa Bay, for instance, she found oil a full eight years after a spill.
If you simply dunked a bucket into Gulf waters and tested for petroleum, she notes, you might not find any. But as part of an ongoing project, Mote researchers are employing
innovative sampling mechanisms that use pieces of
dialysis tubing, which trap oil residue much like a marine organism's tissue does as it filters water. Deployed in metal containers, the pieces tubing gradually filter water over time, collecting any contaminants present.
This oil can persist through a few different mechanisms. After coating sediments, the viscous substance can stick to them for years. There's also evidence that some oil was trapped in the sunken Deepwater Horizon rig itself and
continues to slowly bubble upward, accounting for the
visible sheens of oil occasionally seen on the water's surface.
Comment: But people were surprised; nobody remembers what happened last month, much less in the 9th and 18th Centuries!
That's because since then and now, things were much calmer. In addition, there's the problem of misinterpreting earthquakes for meteor events, both then and now.
This research is trying to suggest that there is a gradual increase or constant uniformity to the rate of environmental disasters, but the evidence for cyclical catastrophism is writ large in the geological, palaeontological and archaeological records.