Weekend Open Thread

Welcome to the weekend! Today is my only real day off for 10 days (I’m flying out again Sunday for another business trip) so I’m planning on spending today doing errands. Do you have weekend plans?

The news magazine of the American Chemical Society, Chemical & Engineering News devoted a special issue to the oil spill in the Gulf. It’s worth checking out the whole thing but this article had a good discussion of the dispersants being used on the oil:

Because chemical dispersants injected underwater at the leak’s source will create smaller droplets with more surface area per volume, plumes may rise even more slowly, says environmental engineer Eric Adams of Massachusetts Institute of Technology. A 0.5-mm-diameter oil droplet will take about two days to make the almost-mile-long journey to the surface, Adams says, whereas a droplet half that size will spend a week rising. Add in denser deep water and some dispersed oil plumes could spend more than a week in the water.

The more time oil spends in the water column, the greater the amount of the oil’s more soluble—and more toxic—compounds can dissolve into the ocean. The plume reported by USF researchers appeared to contain large amounts of dissolved hydrocarbons, according to a USF press release.

A stalled plume eventually breaks up and spreads out through the water column. Such traveling plumes concern Larry McKinney, the executive director of Texas A&M University’s Harte Research Institute for Gulf of Mexico Studies. A plume that reaches upwelling areas, such as the De Soto Canyon 80 miles northeast of the wellhead, could spread oil even farther, because these regions act like conveyor belts that pull water and nutrients from deep waters to the surface. But any oil that doesn’t degrade or dissolve into the water column will eventually reach the surface, Adams says.

…

The bigger environmental concern, experts say, is therefore not the dispersants themselves but what the chemicals do to the oil. By itself, oil is more toxic than dispersants alone, but less so than dispersed oil. In the Corexit toxicity experiments, oil alone had an LC50 of 10.72 ppm. When spill response teams approve dispersant use, they assume that the vast water column will dilute the dispersed oil and mitigate its increased toxicity.

Basically, experts believe that more toxic but significantly diluted dispersed oil floating in the ocean beats less toxic but concentrated oil slicks washing ashore. The 2005 NRC dispersant report describes this decision as a trade-off: Although dispersant-wielding clean-up crews expose water-column communities to the crude, they spare shoreline habitats.

You’re damned-if-do and damned-if-you-don’t. We’re in a lose-lose situation. Thanks BP!

Since we’re talking about science, take a look at the 2010 Art of Science gallery. There’s so many interesting images but this is my favorite – polymer snowflakes.

Polymer Snowflakes
Onobu Akogwu (GS) and Gerald Poirier (senior research specialist)

Mechanical & Aerospace Engineering, Imaging and Analysis Center
This image illustrates dendritic fractal growth patterns resembling snowflakes in the P3HT:PCBM polymer blend. These carbon-rich structures give us important information for understanding a degradation mechanism that affects the performance of polymer blends for organic solar cells.

This image was taken with a state-of-the-art FEI Quanta 200 FEG Environmental Scanning Electron Microscope at Princeton University’s Image and Analysis Center.

Flip through the images, they’re beautiful and interesting.