ChemCentre Petroleum Chemistry Team Leader Leif Cooper explained that all crude oil deposits have a different ‘fingerprint’ which can be used to link an oil spill with a source.
“All crude oil deposits were made at different times under different conditions, so they each have different biomarkers,” he said. “We can look for these biomarkers – chemicals called hopanes, steranes and PAHs (poly-aromatic hydrocarbons) – and determine the different mixes of them in an oil sample to identify what we call the oil’s fingerprint. We can then compare one sample’s fingerprint with another and determine if they are the same oil, or different oils.
“In the case of an oil spill, we analyse samples from the received environment and compare them to samples from possible sources. In a case such as the spill that occurred in Darwin last month, the authorities identify possible sources, take samples and send them to us for analysis, along with samples taken from the oil slick.
“It’s then our job to see if there is a match. Equally importantly, of course, is ruling out some sources and saying the oil didn’t come from there; it’s important to know where it didn’t come from, as well as determining where it did come from.”
Leif said the biomarkers vary so much that a fingerprint will usually uniquely identify a source.
This information will be used in future inquiries into the case. Analyses such as these provide scientifically rigorous and legally defensible evidence, assisting both industry and government to maintain compliance in important areas of environmental protection and regulation.
Image caption: The Darwin oil spill spread over a significant distance. Image source: ABC NEWS / Department of Land Resource Management.