Monitoring of classical, oxidized, and heteroatomic naphthenic acids species in oil sands process water and groundwater from the active oil sands operation area Rongfu Huang a , Yuan Chen a , Mohamed N.A. Meshref a , Pamela Chelme-Ayala a , Shimiao Dong a , Mohamed D. Ibrahim a , Chengjin Wang a , Nikolaus Klamerth a , Sarah A. Hughes b,c,d, ⁎, John V. Headley e , Kerry M. Peru e , Christine Brown f , Ashley Mahaffey g , Mohamed Gamal El-Din a, ⁎⁎ a Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada b Shell Health – Americas, Shell Oil Company, Woodcreek E276K, 150 North Dairy Ashford Road, Houston, TX 77079, USA c Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 1H9, Canada d Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC 29634, USA e Environment and Climate Change Canada, 11 Innovation Boulevard, Saskatoon, SK S7N 3H5, Canada f Shell Canada Ltd. Shell Technology Centre Calgary, 3655 36 St NW, Calgary, AB T2L 1Y8, Canada g Coral Waters Consulting Inc., Shell Technology Centre Calgary, 3655 36 St NW, Calgary, AB T2L 1Y8, Canada HIGHLIGHTS • Analysis of classical, oxidized, and heteroatomic NA species in 30 water samples • Semiquantitative and qualitative analy- sis of NAs using UHPLC-TOF-MS and FTICR-MS • PCA analysis for source differentiation and marker compounds screening • Observation of distinct compositions of NA species with different water types GRAPHICAL ABSTRACT abstract article info Article history: Received 5 April 2018 Received in revised form 9 July 2018 Accepted 9 July 2018 Available online xxxx Editor: D. Barcelo The classical, oxidized, and heteroatomic naphthenic acids (NAs) species were monitored in the oil sands process water (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 O x –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 O x –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 O 2 –NAs or O 4 –NAs could be used for differentiation of water types. O 2 –NAs with n = 12–16 and |Z| = 4–6, and O 4 –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 Keywords: Oil sands process water Groundwater Environmental monitoring Science of the Total Environment 645 (2018) 277–285 ⁎ Correspondence to: S. A. Hughes, Shell Health-Americas, Shell Oil Company, Woodcreek E276K, 150 North Dairy Ashford Road, Houston, TX 77079, USA. ⁎⁎ Correspondence to: M. Gamal El-Din, 7-285 Donadeo Innovation Centre for Engineering, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada. E-mail addresses: s.hughes@shell.com (S.A. Hughes), mgamalel-din@ualberta.ca (M. Gamal El-Din). https://doi.org/10.1016/j.scitotenv.2018.07.111 0048-9697/© 2018 Published by Elsevier B.V. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv