Profiling oil sands mixtures from industrial developments and natural groundwaters for source identification

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Hydrogeology

Background:

• Oil sands process-affected water (OSPW) poses a risk of groundwater contamination in Alberta, Canada.
• Traditional methods struggle to differentiate OSPW from natural groundwater sources.
• Understanding OSPW migration is critical for protecting water resources.

Purpose of the Study:

• To identify specific chemical markers distinguishing OSPW in groundwater.
• To assess the extent of OSPW migration towards the Athabasca River.
• To validate advanced analytical techniques for OSPW source identification.

Main Methods:

• Level-1 analyses: Geochemistry, total naphthenic acids (NAs), and synchronous fluorescence spectroscopy (SFS).
• Level-2 analyses: Electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOF/MS).
• Profiling of oil sands acid-extractable organics (AEOs) using advanced mass spectrometry and chromatography.

Main Results:

• Level-1 analyses identified samples with significant oil sands acid-extractable organics (AEOs) but lacked source differentiation.
• Level-2 analyses successfully differentiated OSPW from natural groundwater using O2:O4 ion class ratios (ESI-HRMS) and specific monoaromatic acid ions (GC × GC-TOF/MS).
• AEO profiles in groundwater samples near tailings ponds resembled OSPW, indicating a common source and migration.

Conclusions:

• Advanced mass spectrometry and chromatography are effective tools for identifying OSPW in groundwater.
• Groundwater affected by OSPW is migrating and potentially reaching the Athabasca River system.
• These findings highlight the importance of continuous monitoring and advanced analytical methods for environmental protection.