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Biogeochemistry of organic matter and associated elements along the river-estuary-ocean continuum
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Monitoring of classical, oxidized, and heteroatomic naphthenic acids species in oil sands process water and groundwater from the active oil sands operation area
Wednesday 9th @ 1410-1430, Conference Hall
Rongfu Huang* , Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada, T6G 1H9
Pamela Chelme-Ayala, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada, T6G 1H9
Sarah A. Hughes, Shell Health - Americas, Shell Oil Company, Woodcreek E276K, 150 North Dairy Ashford Road, Houston, TX, USA, 77079
John V. Headley, Environment and Climate Change Canada, 11 Innovation Boulevard, Saskatoon, SK, Canada, S7N 3H5
Mohamed Gamal El-Din, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada, T6G 1H9
Presenter Email: rongfu@ualberta.ca |
Oil sands process water (OSPW) is a mixture of organic and inorganic constituents generated after bitumen extraction process by the oil sands industry. OSPW is currently stored in tailings ponds for recycling back into the extraction process, and is not discharged into natural environment because bitumen-derived dissolved organic compounds (primarily naphthenic acids; NAs) are toxic to aquatic and terrestrial organisms through multiple modes of action, including narcosis, endocrine disruption, immunotoxicity, and carcinogenicity. NAs are a complex mixture of carboxylic acids and are considered to be the organic constituents of primary eco-toxicological concern in OSPW. The seepage of OSPW into groundwater was suspected to be a reason responsible for the NAs detected in the river water of the surrounding areas. In this work, the classical, oxidized, and heteroatomic NAs species were monitored in the OSPW and groundwater from the active oil sands operation area, using solid phase extraction sample preparation and high resolution mass spectrometry analysis. Groundwater samples include Pleistocene channel aquifer groundwater (PLCA) and oil sands basal aquifer groundwater (OSBA) from different depth of underground. The concentrations of Ox−NAs decreased from OSPW to PLCA, and then increased from PLCA to OSBA, which is deeper than PLCA. The NAs in PLCA mainly comprised of Ox−NAs and N−NAs and the percentage of S−NAs was negligible. Results revealed relative abundances of individual NA species in total NAs varies among different water layers and the potential environmental impacts are expected to be variable. Principal component analysis results of O2−NAs or O4−NAs could be used for differentiation of water types. O2−NAs with n =12−16 and |Z| = 4−6, and O4−NAs with n = 14−20 and |Z| = 6−8, were identified as marker compounds that could serve as surrogates of the larger complex NA mixture for source differentiation. This work utilized a combination of sample preparation, instrumental analysis, and statistical analysis methods to obtain knowledge of the occurrence, composition, and transfer of NAs in the groundwater of the Alberta oil sands operation area. |
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