Examining the weathering susceptibility of light biomarkers

ABSTRACT

In a recent article, Malmborg and Nordgaard (2016) have suggested an expanded set of diagnostic ratios for chemical fingerprinting of mid-range petroleum distillates. However, the susceptibility to weathering of these compounds must also be established if the suggested ratios are to be useful in environmental spill cases. The weathering behavior of eight compound classes was examined by studying the fate of diesel oil samples applied to a water surface and to potting soil in a laboratory setting. The time frame used was up to 4 days (water) and up to 30 days (soil). Biodegradation was found to severely affect aromatic and aliphatic compounds, but decalins, adamantanes, and bicyclic sesquiterpanes remained microbially stable. Evaporation was the primary weathering process for the examined compounds on the water surface and can probably eliminate many compounds before other signs of weathering are observed in mid-range petroleum distillates spilled at sea. All compound classes were mainly persistent to dissolution and photo-oxidation during the time frames investigated.

KEYWORDS:

• Oil fingerprinting
• biomarker
• forensic
• weathering
• diesel

Acknowledgment

The author would like to thank Helén Turesson, National Forensic Centre, Sweden, for assisting in identification of the isoprenoids.