Research Technical Report

Identification of Chronic Oiling Sources in California

Henkel, L., and M. Martin (December 2016)

California Department of Fish and Wildlife, Office of Spill Prevention and Response Technical Report 16-01

Rapid identification of petroleum samples is critical for effective response to mystery oil spills. In California, mystery spills (spills with an unknown source) may be anthropogenic or may be related to productive natural petroleum seeps. In this report, we provide two types of information to help with identification of mystery spill samples in California. In Chapter 1, we present a new method of quickly comparing quantified aspects of an oil “fingerprint” from a mystery sample to a large database of potential sources and other samples. Using simple relative percent difference among a series of biomarker ratios (compared using programming language R), we were able to quickly narrow down potential matching samples that could be confirmed using more standard fingerprinting techniques. In Chapter 2, we present information on specific groups of matching samples presumed to be related to natural seeps in California, identified in part using methods described in Chapter 1. These 10 groups include samples from tar balls and oiled wildlife, and in four cases are linked to specific source seeps. This is one of few reports linking mystery samples to specific seeps, and we also present information on some seeps off central California that previously were not well documented. These groups of matching samples provide a starting point for comparison of future mystery samples, and provide a greater understanding of the dynamics of chronic oiling from seeps in California.