Diagnostic ratio analysis : a new concept for the tracking of oil sands process-affected water naphthenic acids and other water-soluble organics in surface waters

Abstract

A diagnostic ratio forensics tool, similar to that recognized internationally for oil spill source identification, is proposed for use in conjunction with existing LC/QToF quantitative methodology for bitumen-derived water-soluble organics (WSOs). The concept recognizes that bitumen WSOs bear a chemical skeletal relationship to stearane and hopane oil biomarkers. The method uses response ratios for 50 selected WSOs compared between samples by their relative percent difference and adopted acceptance criteria. Oil sands process-affected water (OSPW) samples from different locations within a single tailings pond were shown to match, while those from different industrial sites did not. Acid extractable organic samples collected over 3 weeks from the same location within a single tailings pond matched with each other; as did temporal OSPW samples a year apart. Blind quality assurance samples of OSPW diluted in surface waters were positively identified to their corresponding OSPW source. No interferences were observed from surface waters, and there was no match between bitumen-influenced groundwater and OSPW samples, as expected for different sources. Proof of concept for OSPW source identification using diagnostic ratios was demonstrated, with anticipated application in the tracking of OSPW plumes in surface receiving waters, together with the potential for confirmation of source.