Spectrometric analysis of the metabolism and adsorption of naphthenic acid fraction compounds in a phytoremediation treatment system
Abstract
Bitumen mining in northern Alberta produces large volumes of oil sands process-affected water (OSPW) that require treatment before being released into the environment. Naphthenic acid fraction compounds (NAFCs) are considered primary contributors to OSPW toxicity; therefore, remediation efforts often target these compounds. Phytoremediation is proposed as a feasible treatment for OSPW using a constructed wetland treatment system (CWTS) strategy due to the cost-effective and low-maintenance nature of this technology. A CWTS uses plants and their associated microorganisms to take advantage of natural metabolic processes for the uptake and biotransformation of environmental contaminants. While CWTSs for OSPW treatment have demonstrated success in attenuating NAFCs and reducing toxicity in mesocosm and pilot-scale studies, the fate of NAFCs in a CWTS is not well understood. This thesis research aimed to gain insight into NAFC fate in CWTSs by exploring NAFC biotransformation processes in plant tissues and the adsorption characteristics of NAFCs onto sediment substrates. A method for extracting NAFCs and their metabolites from plant tissues was developed and used to extract the isotopically labelled model compound 1-adamantanecarboxylic acid (¹³C-AdCA) and NAFCs from OSPW. This method, in combination with high-resolution Orbitrap mass spectrometry, was used to track the uptake, translocation, and biotransformation within plant roots and shoots. These experiments showed a general decrease in compound abundance over time, indicative of transformation events. The OSPW treatments further demonstrated that the majority of NAFCs were completely transformed in root and shoot tissues. Additionally, incubation studies were conducted to test parameters associated with NAFC adsorption onto various sediments. The adsorption of NAFCs from OSPW onto a sediment substrate from the oil sands region appeared to be impacted by the properties of the OSPW itself, including NAFC concentration, class differences, or shifts in carbon number and double bond equivalents. Other factors, such as water quality characteristics, may also impact adsorption. Overall, the results of this research provide insight into the fate of NAFCs in phytoremediation systems, guiding future metabolomics studies and considerations for the large-scale implementation of plant-based technologies in OSPW treatment strategies.
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Citation
Charriere, C. (2024). Spectrometric analysis of the metabolism and adsorption of naphthenic acid fraction compounds in a phytoremediation treatment system (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.