Assessment of vanadium and nickel enrichment in Lower Athabasca River floodplain lake sediment within the Athabasca Oil Sands Region (Canada). (October 2020)

• Record Type: Journal Article
• Authors: Klemt, Wynona H.; Kay, Mitchell L.; Wiklund, Johan A.; Wolfe, Brent B.; Hall, Roland I.
• Is Part Of: Environmental pollution. Volume 265(2020)Part A
• Publication Date: 2020-10
• Subjects: River pollution -- River sediment quality -- Paleolimnology -- Lower Athabasca River -- Pre-development baseline metals concentrations; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2020.114920
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Sediment quality monitoring is commonly used to assess for river pollution by industrial activities, but requires knowledge of pre-disturbance conditions. This has long been a critical knowledge gap for assessing pollution of the Lower Athabasca River within the Athabasca Oil Sands Region (AOSR) because sediment quality monitoring started 30 years after mining operations began in 1967. Here, we analyze oil-sands pollution indicator metals vanadium (V) and nickel (Ni) in sediment cores from five Athabasca River floodplain lakes spanning from 17 km upstream to 58 km downstream of central oil sands operations. These data are used to define pre-development baseline (i.e., reference) concentrations and assess for enrichment in sediment deposited after 1967. Measurements of organic and inorganic matter content were used to differentiate periods of strong and weaker Athabasca River influence in the sediment records, as needed to discern pathways of metal deposition. Numerical analyses reveal that post-1967 V and Ni enrichment factors have remained below the 1.5 threshold for 'minimal enrichment' ( sensu Birch, 2017) in stratigraphic intervals of strong river influence in the floodplain lakes. Thus, concentrations of V and Ni carried by Athabasca River sediment have not become measurably enriched since onset of oil sands development, as demonstrated by our before-after study design with >99.99% power to detect a 10% increase above pre-development baselines. At the closest lake (<1 km) to oil sands operations, however, enrichment factors for V and Ni increased to 2.1 and 1.5, respectively, in the mid-1980s and have remained at this level when river influence was weaker, indicating contamination via atmospheric transport. Localized enrichment within the oil sands region via atmospheric pathways is a greater concern for ecosystems and society than local and far-field transport by fluvial pathways. Graphical abstract: Image 1 Highlights: Lack of pre-impact data = pollution unknown for Athabasca River in oil sands region. Established pre-development river-sediment [V] & [Ni] from 5 floodplain lake cores. At a central site, detected localized enrichment of V and Ni via aerial pathways. Detected no enrichment of Athabasca River supplied sediment since development. Our before-after study design improves upon prior space-for-time approaches. Abstract : Established pre-development baselines; detected localized enrichment of V and Ni in floodplain lake sediment via atmospheric deposition but little to no enrichment of Athabasca River sediment within the Athabasca Oil Sands Region.