Performance of wetland forbs transplanted into marshes amended with oil sands processed water
Companies mining oil sands in Alberta (Canada) face the challenge of reclaiming wetlands under water use restrictions. Wetland reclamation after mining will generate marshes characterized by elevated salinity and residual hydrocarbons. Oil sands wetlands are also impoverished in forbs, suggesting that their establishment may be constrained by water chemistry. We transplanted skullcap, mint, and smartweed plants into experimental trenches that simulated two possible reclamation scenarios: wetlands amended with on-site freshwater or with oil sands processed water (OSPW). The main scientific question was is OSPW a suitable water amendment as freshwater for reclaiming wetland forb habitat? As a surrogate of plant health, we studied plant ecophysiology (gas exchange, leaf fluorescence), leaf chemistry, and plant growth. Results showed that there were no differences in skullcap mineral contents under either treatment; however, mint and smartweed plants subjected to OSPW had a significantly higher Na content than those under freshwater. Smartweed dark-adapted leaf fluorescence showed a reduced photochemistry in OSPW relative to plants in freshwater. Mint leaves exhibited lower stomatal conductance in OSPW than in freshwater, a condition that negatively affected transpiration and carboxylation. Skullcap plants grown in OSPW had lower net CO2 assimilation rates than those in freshwater but did not show any other ecophysiological difference between treatments. Mint plants experienced growth reductions (i.e., shoot height) in OSPW. Our results show, for the first time in the literature, that plants photosynthetic capacity was negatively affected by OSPW. Conditions in OSPW proved to be suitable for establishment as transplanted forbs showed 100 % survival after the first growing season. However, impaired physiological functions in plants subjected to OSPW indicated that OSPW amendment created a less hospitable habitat for wetland forbs than freshwater.
KeywordsBitumen Effluent Freshwater amendment Salinity Wetland reclamation
We thank Christine Daly, Josh Martin, Curtis Vieville, and Heidi Keillor for helpful assistance. This study was supported by grants from The National Science and Engineering Research Council of Canada under their CRD program, the Alberta Water Research Institute (AWRI), and with support from an organized consortium of industrial cooperators including Canadian Natural Resources Ltd., Imperial Oil Ltd., Shell Canada, Suncor Energy Inc., Syncrude Canada Ltd. and Total E&P Canada. MC Roy received a fellowship from Northern Scientific Training Program and Canadian Circumboreal Institute.
Compliance with ethical standards
Research undertaken was partially funded by an oil sands research consortium fund (Syncrude, Suncor, Albian, Shell, and Petrocan) accessed as matching dollars for Collaborative Research Development (CRD) with the Natural Sciences and Engineering Research Council of Canada (NSERC). The University of Alberta’s Intellectual Property Agreement and legal oversight of fund acceptance ensured complete academic freedom and private holding of data as a condition of accepting support. Research results and publication are completely isolated from partner influence.
Conflict of interest
The authors declare that they do not have conflicts of interest.
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