Gas station oil leakage contaminations increase as rapid growth of private gas stations. Due to frequent change of gas station ownerships and oil suppliers, attribution of leakage contamination responsibility is difficult to clarify and create lots of controversy. Development of forensic techniques for gasoline and diesel pollution investigation has its urgency. Recently the EPA actively promote environmental forensic oil fingerprinting technology concepts and apply to oil pollution investigations. This project：「Apply environmental Forensic Techniques to Establish Commercial Diesel Fingerprint Investigation Plan」started on May, 2013 can fulfill such purpose.
In this final report the following contents are accomplished and fulfilled: The first part, regarding the collection of relevant forensic oil spill identification papers:
(1) Total of 204 oil spill identification related technologies papers and documents have been collected, analyzed, and edited as an Excel database for easily sorting and review.
(2) The oil spill identification methodology and protocol/decision chart are reviewed, explained, and compared
(3) Two case studies are explained and over 20 research papers are briefly translated into an easily readable format.
(4) Draft version of the procedure of identification of sources of diesel oil spills is developed.
The Second part, regarding the development of GC/MS analytical methodology for diesel oil, oil samples taken from gas stations operated by CPC and FPC were performed on a Agilent Model 7890A GC equipped with an Agilent Model 5975C mass-selective detector. System control and data acquisition were achieved with an Agilent Chemstation. The various screening conditions, linearity and accuracy (reproducibility) of instrument working ranges, etc. were carried out and the optimal experimental conditions are determined.
The third part is focused on the analysis of chemical fingerprint distributions and biomarker diagnostic ratios of CPC and FPC refinery products. Total of 72 crude oils and 35 refined diesel samples were performed and compared. The major differences caused by distillation process, desulfurization process as well as addition of 2% biodiesel procedure are discussed in detail.
The fourth part regarding GC/MS analysis of over 141 diesel samples collected directly from CPC and FPC gas stations with different locations and areas were completed and detailed analytical results are presented. Base on the overwhelming information gathered from GC/MS data such as chemical fingerprints and biomarker diagnostic ratios, the appropriate diagnostic ratios are chosen for the purpose of diesel oil identification.The differences between CPC and FPC diesel oils can be clearly identified and distinguished with the application of principal component analysis (PCA) statistical techniques associated with the most appropriate diagnostic ratios.
The fifth part, GC/MS analysis of 10 contaminated soil samples and 1 monitoring wells oil samples collected from 4 diesel contaminated sites were completed and results indicated that, under microbial degradation, fingerprints of some compounds can still be applied in a certain degree for diesel spilled identification.