A new study brings to the surface some disturbing evidence about the scope and lasting impact of the BP spill on the Gulf of Mexico.

In a report published Thursday, scientists say a 22-mile-long invisible mist of oil is lingering far below the surface of the Gulf, poses a continued threat to marine life and ecosystems.

That’s not surprising news to many people, who have discounted the declaration of top federal officials that the oil spill was mostly “gone.”

“Gone,” it seems, relates only to what is visible.

And as this study points out, the real threat lurks beneath the surface.

The oil plume, which is about 40 miles off the coast of Louisiana, could contain as much as 42 million gallons of oil, scientists estimate.

Some 3,000 feet below the surface, the oil is breaking down, but at a rate about one-tenth as slow as the oil on the surface. That means it could likely linger for months, even years.

And, because the oil has broken into a cloud-like mist, it can easily be absorbed by the organisms that live in the deeper waters. These small fish and crustaceans are a critical part of the food chain, providing the food for many of the fish and seafood harvested from the more shallow waters, as well as large mammals who feed off them.

Scientists warn that they just don’t know what the long-term impact will be on the ecosystem, and that is frightening.

The scientific evidence proves the threat from this spill isn’t “gone.” And federal officials would be well-served to remember that, keeping a focus for years to come on our precious Gulf of Mexico.