If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Diamondoids For Tracing Oil Spills

Naturally occurring compounds can lead investigators to source of fuel spills

by Sarah Everts
August 28, 2006 | A version of this story appeared in Volume 84, Issue 35

Credit: Big Stock Photo
Diamondoids like diamantane (at top) can fingerprint diesel that leaks from tanks like the one above.
Credit: Big Stock Photo
Diamondoids like diamantane (at top) can fingerprint diesel that leaks from tanks like the one above.

Forensic investigators searching for oil spill culprits have a new tool for tracking down whodunit. Researchers at Environment Canada, in Ottawa, characterized diamondoid compounds for use in fingerprinting spilled oil distillates of low or medium molecular weight, such as diesel and jet oil (Environ. Sci. Technol., DOI: 10.1021/es060675n).

When environmental chemists want to track down the origin of a spill, they compare−often using a combination of gas chromatography and mass spectrometry−the constituents of spill samples with suspected sources. Commonly used biomarkers for crude oil spills are high-molecular-weight terpanes and steranes that get removed during refining and are therefore not ideal for fingerprinting lighter distillates. But lighter distillates are often implicated in groundwater contamination from underground fuel receptacles at gas stations or military bases. Sinking ships also release light- to midrange distillates because they use diesel in fuel, either directly or as an agent to reduce fuel viscosity.

Enter the diamondoids, a family of rigid, three-dimensionally fused cyclohexyl alkanes such as diamantane. With cage structures that look, as one might suspect, like diamonds, the compounds are naturally occurring in oil.

The ratio of different diamondoid compounds provides a regional signature for the oil's origin, says study author Zhendi Wang. The flora and fauna in Saudi Arabia vary from those in Alberta, so when organic matter decomposes with heat and pressure, diamondoids are produced in varying amounts, providing a regional signature.

During refining, diamondoids are concentrated in petroleum products. To boot, the researchers find that higher-molecular-weight diamondoids are not easily removed by evaporative weathering or altered by microbial degradation. This means diamondoids remain a usable forensic standard over a long period of time.

"Previous methods leave a lot to be desired for light- to midrange spills," comments Jeffrey W. Short, a research chemist with the National Oceanic & Atmospheric Administration's National Marine Fisheries Service. "This new method fills a void."



This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.