Application of artificial substrate samplers to assess enrichment of metals of concern by river floodwaters to lakes across the Peace-Athabasca Delta
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Date
2021-05-19
Authors
Savage, Cory
Advisor
Hall, Roland
Wolfe, Brent
Wolfe, Brent
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Potential for downstream delivery of contaminants via Athabasca River floodwaters to lakes of the
Peace-Athabasca Delta (PAD), northeastern Alberta (58.6°N, 111.8°W), has raised local to international
concern. Prior investigations have shown metals concentrations in sediment of lakes supplied by river
floodwaters are not enriched above pre-industrial baselines. Additional real-time aquatic ecosystem
monitoring approaches are needed to complement sediment-based techniques where time intervals
captured are uncertain. Here, we quantify enrichment of eight metals (Be, Cd, Cr, Cu, Ni, Pb, V, Zn) at
the base of aquatic food webs, relative to sediment-based pre-industrial baselines, via analysis of
biofilm-sediment mixtures accrued on artificial substrate samplers deployed during summers of 2017
and 2018 in >40 lakes spanning hydrological gradients of the PAD. Widespread flooding in spring 2018
allows for assessment of metals enrichment by Athabasca River floodwaters. A main finding is that river
floodwaters are not implicated as a pathway of metals enrichment to biofilm-sediment mixtures in PAD
lakes from upstream sources. MANOVA tests revealed no significant difference in residual
concentrations of all eight metals in lakes that did not flood versus lakes that flooded during one or both
study years. Also, no enrichment was detected for concentrations of biologically inert metals (Be, Cr,
Pb), and those related to oil-sands development (Ni, V). Enrichment of Cd, Cu, and Zn at non-flooded
lakes, however, suggests uptake of biologically active metals complicates comparisons of organic-rich
biofilm-sediment mixtures to sediment-derived baselines for these metals. Results lend confidence that
this novel approach could be adopted for lake monitoring within the Wood Buffalo National Park Action
Plan.
Description
Keywords
Contaminant monitoring, Periphyton, Floodplain, Peace-Athabasca Delta, Athabasca Oil Sands