Metal bioaccumulation and effects biomarkers in mussels caged in the Athabasca OS mining area

The Athabasca oil-sand (OS) deposit area is the largest world's known stock of crude bitumen and the third-largest proven crude oil reserve. Mining activity is well known to release associated contaminants, such as metals, and causes potential risk to the environment and aquatic life. The purpose of this study aimed to determine the impacts of OS mining on water quality and mussels in the area of Fort McMurray, Northern Alberta (Canada), for 2 consecutive years which showed different river water flow and metals coefficient of distribution. Autochthonous mussels (Pyganodon grandis) were placed in cages and in-situ exposed in the Athabasca R. for 4 weeks. Thereafter, metals and inorganic elements, including rare earth elements, were analyzed in water, and mussel gills and digestive glands to evaluate bioaccumulation, bioconcentration factor (BCF) and determine the resulting effects by measuring biomarkers of stress. This study clearly shows high bioaccumulation of Be (2012), V, Ni and Pb (2013) in mussel digestive glands in the Steepbank R. which flows directly of OS mining area than at the reference site, while Al, V, Cr, Co, Ni, Mo (2012) and Ni (2013) were significantly higher in mussel gills which shows different pathways of exposure for V and Ni. Metals exposure consequently impacted metallothionein and lipid peroxidation (oxidative tissues damage) in mussel. These results confirm that some metals and inorganic elements are bioavailable in mussel tissues, which was associated to metal detoxification and oxidative stress in mussels located downstream OS mining area.