On an average summer day, a storm like tropical storm Bonnie would elicit yawns from hurricane-hardened Gulf Coast residents. But with the remains of the BP oil spill bobbing just off Louisiana, concerns are rising that Bonnie could wreak havoc far beyond the capacity of a normal summer storm.
Bonnie is expected to make landfall early Sunday near the mouth of the Mississippi River with 40 mile per hour winds and a possible four-foot storm surge. The prospect of toxic oil residue surging into low-lying communities is not sitting well with Gulf Coast residents.
Along Louisiana's coastline, parish officials are preparing residents for possible evacuation, even though oil has stopped leaking into the Gulf and hundreds of cruising skimmers could only find 50 barrels of oil to collect on Thursday. But Bonnie could give researchers insight into the extent to which kerosene dispersants have ultimately helped or hurt the Gulf oil spill relief effort.
IN PICTURES: Destructive Oil Spills
"A hurricane or tropical storm at this point may help us remix the water columns and accelerate bacterial activity, but the downside is if the [oil] is not degraded and a storm accelerates its transport, even subsurface stuff, where we may see dissolved oil come up into shorelines and estuaries," says Richard Snyder, director of the Center for Environmental Diagnostics and Bioremediation in Pensacola, Fla. "The floating stuff we can catch at the inlets, but the dissolved stuff? There's no way to stop it."
At the least, Bonnie is forcing communities to undo some of the protective work they've laid along the coastal marshes and beaches. Workers are unmooring miles of floating boom amidst concerns that they could become airborne projectiles or break apart and wash up into sensitive marshes where their removal could damage grass beds and fish nurseries.
In hard-hit Plaquemines Parish, La., workers are preparing sandbags and pumping out drainage canals in anticipation of the storm. Although heavy upper winds are currently weakening Bonnie, residents know from experience that anything can happen once a tropical system enters the warm Gulf waters.
"What we are very worried about is the oil getting pushed farther inland along the coast," Louisiana Gov. Bobby Jindal told ABC News.
A mystery: Where's the oil?
Scientists don't know how fast bacterial microbes are degrading the up to 4.2 million barrels (180 million gallons) of oil that ultimately blew out of the Macondo well after the April 20 Deepwater Horizon rig accident that killed 11 workers.
So far, according to BP, 1.1 million barrels of the floating oil has been either skimmed or incinerated at sea. Much of the dispersed oil – which still has toxicity – is suspended in the Gulf's deep water columns.
"What we don't know is, in those dispersed layers, what's still there and what's the concentration," says Dr. Snyder. "Knowing that would help us define what impact a tropical storm or hurricane would have and to what extent a storm" would push the spill into estuaries.
Bonnie's potential gift to Louisiana
While little oil is visible around places like Golden Meadow, La., locals have seen evidence that dispersants have caused blobs of oil to fall to the bottom. Fish that would normally be spawning on the bottom aren't and bottom-dwelling crabs seem to be scrambling to higher ground, even onto floating debris – signatures of something being wrong below the surface.
If a storm stirs up the oil from the bottom, that could be a "good thing," says Mary, a Golden Meadow resident who asked her last name not be mentioned since her husband is working for BP.
"Once the water is stirred up and it brings the oil up from the bottom, we know darn well that they're not going to leave us high and dry here, because we're going to know where the oil is," she says. "People down here, we know our waters and we know what's going on."
IN PICTURES: Destructive Oil Spills