Oil Detection Methods Miss Important Class of Chemicals

MTorrice writes "For decades, scientists studying oil spills have relied on the same analytical methods when tracking the movement of oil and assessing a spill's environmental impact. But these techniques miss an entire class of compounds that could account for about half of the total oil in some samples, according to research presented last week at the Gulf of Mexico Oil Spill & Ecosystem Science Conference, in New Orleans. These chemicals could explain the fate of some of the oil released in the 2010 Deepwater Horizon accident and other spills, the researchers say."

Comments

Gas chromatographs again...

[Antipater]

All right, according to the gas chromatograph, the missing oil compound is... love!? Who's been screwing with this thing?

Spoiler

[SuricouRaven]

The overlooked chemical class is oxidized compounds produced by the oil degrading after the leak, usually ignored because they are more difficult to measure than plain old hydrocarbons.

Re:Spoiler

[mapsjanhere]

Not really, but with enough oxygen in it they start decomposing at the temperature of vaporization, producing short chain material that the automatic sample analysis suppresses. If you manually evaluate the samples you can still see it. Problem is that you get highly operator dependent results, and that makes comparing samples difficult. Also, once you've started to oxidize the material, biodegradation isn't far behind. So it's not really an environmental problem but literally an academic one.

Re:Spoiler

[mapsjanhere]

Sure it's an exciting science problem to look at - what individual compounds are part of the degradation chain of oil in the environment, how do we analyze it, what's the distribution, and is any of it toxic to wildlife. Plenty a PhD thesis in there. But the journalistic description of "we're missing part of a spill", implying that we're underestimating a problem, isn't really there IMO. Standard analysis gives you the amount of unchanged oil still around, stuff that kills birds by gumming up feathers etc. The oxidized material is quickly going to become water soluble or at least miscible as surfactant, and while not pretty it's going to dilute away in short order.

Re:Spoiler

[sFurbo]

So would releasing tons of O2 under/in the affected area, bubbling up O2 and diffusing in the water cause more rapid decay of the oil?

Yes

Would that make it easier or harder to clean up?

Yes

Or, to be less snarky, oxygen is important in degrading oil, and oxygen depletion makes the oil degrade much slower. And we don't really know how toxic these compounds are. They are more hydrophilic than hydrocarbons, so they are more rapidly taken up and more rapidly excreted by organisms.

Re:Spoiler

[sFurbo]

Worse, even when we figure out where it goes, we don't know how toxic those compounds are. But even that is getting ahead of ourselves, we don't even know how toxic the compounds in oil are. We know how toxic PAH's are, because they are the major component of soot. In oil, however, the amount of alkylated PAH is much higher, and we don't know how toxic they are. Today, we measure the total petroleum hydrocarbon and a few of the PAH's to estimate the severity of pollution, which is fine if you have spilled paraffin and soot, but is probably not a very good probe for the toxicity of crude oil.

Re:Spoiler

[AK Marc]

I'll just pretend it's not that bad and the government will take care of us. The alternative is too depressing.

Oxidized stuff

[vlm]

Oxidized stuff is kind of vague, chemically speaking. I'd love to look at the real paper (as opposed to the journalist interpretation) but I can't gain access. Just spins. Donno if its a free paper or paywall time.

Organic compounds containing oxygen... well, its been 20 years but are they talking about organic acids or ketones or aldehydes or alcohols or some freaky epoxides (that would be a WTF for sure). Doesn't have to be exclusive could be any mix of course.

I'm not a petroleum engineer but I play one on /. After cooking a million years underground I would think any trapped O2 would turn into water and CO2 as opposed to halfway stuff, so this indicates bioavailability after it leaked out... in other words its already half eaten up.

Re:Oxidized stuff

[icebike]

They imply that some of these can kill fish embryos in closed bays and estuaries.

one study linked unidentified oil chemicals to a spike in fish embryo deaths in San Francisco Bay

Really? How do they know it wasn't just raw sewage, or industrial chemicals if they didn't even identify the chemical, or even prove it came from the oil spill?

However, it appears their real complaint is this:

Reddy says overlooking these chemicals could hinder spill research in several ways, including thwarting scientists’ attempts to account for what happens to oil after a spill. After the Deepwater Horizon spill, government and academic groups could only explain the fate of about 75% of the oil released into the Gulf of Mexico. The oxidized compounds could be a portion of this “missing” oil, Reddy says.

Its not that the oil is "missed", its just that the oil once degraded to the point that it is not oil anymore is hard for them to measure with current methods, so they can't figure out where it went.

The main point, is that the oil is gone, degraded, oxidized, etc. The most dangerous (to marine life) part of the spill is gone.
The extent to which it is gone serves as an indirect measure of what these guys are trying to measure.

They offer very little in the way of support for their assertion that these chemicals are harmful.

Re:Oxidized stuff

[NatasRevol]

" The most dangerous (to marine life) part of the spill is gone."

That's an unknown statement, and what the scientists are trying to figure out.