Where did the oil go?

August 3, 2010 4:29:09 PM PDT
On Monday a federal oil spill task force announced that an estimated 172 million gallons of crude spilled into the Gulf of Mexico before the Deepwater Horizon leak was finally capped. But cleanup crews say they have been seeing far fewer oil slicks on the water than they were expecting, and BP says it plans to scale back some of its cleanup effort. So where did the oil go? We tested water from Galveston to Gulf Shores, Alabama and on to Pensacola, Florida. On the way to get water samples we had to dodge tar balls and nasty stuff like up on beaches. But when scientists looked at the water, it came up clean.

We fanned out across the Gulf Coast to see what was lurking offshore -- crossing parking lots full of sticky tarry footprints, beachside showers full of tar balled feet and beaches spoiled with tar patties and tidal pools full of the ugly remnants the nation's worst oil spill ever. Clean up crews were sucking up oil and scooping up tar balls. We fully expected to find oil and the chemicals it leaves behind in the water where families were swimming. Even our experienced environmental consultant expected to find oily remnants.

Eco Serve Consultant Rhett Farrell admitted, "I was expecting to see higher levels of petroleum hydrocarbons."

But the tests down to five parts per million couldn't find oil in the water samples. The tests were somewhat of a surprise. We expected to find remnants of oil in the water, as it turns out there weren't many.

[ READ THE FULL GULF WATER ANALYSIS REPORT FINDINGS ]

Rice University Chemical Engineering Professor Dr. George Hirasaki said, "It doesn't surprise me because I understand the effect of aging on crude oil."

Dr. Hirasaki has decades of experience working with oil. We asked him to explain how oily beaches can be right next to clean water. He says all about time and nature.

It takes about a month for oil to travel the 50 miles from wellhead to beach and nature's working the whole time.

"It's relatively light oil and the Gulf of Mexico is much warmer than Alaskan regions, so you get a lot of biodegradation," explained Dr. Hirasaki.

In other words, that oil is a meal for microbes. This time of year warm waters make microbes extra hungry, speeding up that process and the process of evaporation. But the sun and microbes don't take care of everything. Tar balls are made up of the stuff nature can't get rid of.

The heavy tar is a mess, but doesn't dissolve in water, which is why it washes up next to your beach chair. Wash it off your hands and feet and keep them off the kids sand castles, and you should be OK. The water may be clean, but it doesn't mean the beach always will be.

Dr. Hirasaki said, "That's what's left over once the water-soluble stuff dissolves."

So it's sort of like salad dressing -- shake the oil and water as much as you want and it will eventually separate again. If you test tar balls and residue directly, you'll come up with all sorts of dangerous, carcinogenic stuff. So don't play with these. And there is some concern among scientists about oil and dispersant settling on the gulf bottom mixing with sediment.


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