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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Potential for downstream delivery of contaminants via Athabasca River floodwaters to lakes of the PAD has raised local to international concern. Here, we quantify enrichment of eight metals (Be, Cd, Cr, Cu, Ni, Pb, V, Zn) in aquatic biota, 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 more than 40 lakes. Widespread flooding in the southern portion of the delta in spring 2018 allows for assessment of metal enrichment by Athabasca River floodwaters.

River floodwaters are not implicated as a pathway of metal 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 demonstrate that this novel approach could be adopted for lake monitoring within the federal Action Plan.

These data were collected to address the need for a hydroecological monitoring program, with focus on metals of concern, in the Peace-Athabasca Delta (PAD). To do so, we deployed artificial substrate samplers in ~60 lakes for the duration of the ice-free seasons of 2017 and 2018. We assessed the accrued biofilm-sediment mixtures for enrichment of metals of concern above pre-industrial levels determined from analyses of sediment cores in the PAD. We also related metals enrichment to periphytic algae community composition, inferred from diagnostic algal pigments, to explore taxa-specific rates of active biological uptake of metals of concern.

Dataset associated Journal article:

Cory A.M. Savage, Tanner Owca, Mitchell L. Kay, Jelle Faber, Brent B. Wolfe, Roland I. Hall, Application of artificial substrate samplers to assess enrichment of metals of concern by river floodwaters to lakes across the Peace-Athabasca Delta, Journal of Hydrology: Regional Studies, Volume 38, 2021, 100954, ISSN 2214-5818, https://doi.org/10.1016/j.ejrh.2021.100954.

Peace-Athabasca Delta

Dataset associated journal Article:
https://doi.org/10.1016/j.ejrh.2021.100954