Multi-year trends in the spatiotemporal occurrence and fate of naphthenic acid fraction compounds in a pilot-scale engineered treatment wetland
Loading...
Date
2025
Authors
Vander Meulen, Ian
Ahad, Jason M. E.
Martineau, Christine
Muench, Douglas G.
McMartin, Dena
Headley, John V.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
In the Athabasca Oil Sands region (AOSR) of Alberta, Canada, there are ∼1.4 billion m3 of fluid tailings containing known toxic constituents which will require treatment and must be reclaimed before closure. One class of contaminants of concern are naphthenic acid fraction compounds (NAFCs). While various treatment strategies have been considered, constructed wetland treatment systems (CWTSs) have emerged as a semi-passive, high throughput, and potentially cost-effective option. Here, non-targeted Orbitrap high-resolution mass spectrometry was applied to assess the NAFC remediation efficacy of a 1-ha CWTS operated over two field seasons (2021 and 2022) at a site situated in the Northern of Alberta. Concentrations of total NAFCs decreased consistently during a closed CWTS operation with OSPW recirculation at each field seasons. Concurrently, O2-NAFCs (i.e., classical NAs) steadily decreased while more-oxygen-rich formulae increased in spectral abundance, consistent with oxidative degradation. Attenuation rates of NAFCs were more rapid at the outset of the season (∼0.53 mg/L/d), where treatment rates eventually decreased (∼0.25 mg/L/d). Molecular-level characterization of treatment outcomes showed that the highest molecular weight O2-NAFCs detected (i.e., #C > 14) decreased the most, whereas all O3- and O4-NAFCs generally increased in relative spectral abundance. Shallow, heavily vegetated cells of the wetlands tended to have lower NAFC concentrations and more oxygen-rich compounds, suggesting substantial attenuation of NAFCs in these segments. These results demonstrate that this field-scale CWTS effectively in depletes and transforms OSPW-derived NAFCs under environmental conditions found in the AOSR
Description
Open access article. Creative Commons Attribution 4.0 International license (CC BY 4.0) applies
Keywords
Naphthenic acid fraction compounds , Athabasca Oilsands , Pilot-scale wetlands , Engineered wetlands , Tailings pond water reclamation , Orbitrap-MS analysis
Citation
Vander Meulen, I., Ahad, J. M. E., Martineau, C., Muench, D. G., McMartin, D. W., & Headley, J. V. (2025). Multi-year trends in the spatiotemporal occurrence and fate of naphthenic acid fraction compounds in a pilot-scale engineered treatment wetland. Journal of Environmental Chemical Engineering, 13(5), Article 117568. https://doi.org/10.1016/j.jece.2025.117568