Elevated exposure, uptake and accumulation of polycyclic aromatic hydrocarbons by nestling tree swallows (Tachycineta bicolor) through multiple exposure routes in active mining-related areas of the Athabasca oil sands region

Abstract

In the Athabasca Oil Sands (OS) Region, the exposure (by air, water, diet), uptake and deposition of polycyclic aromatic compounds (PACs), including parent and alkylated hydrocarbons (PAHs) and dibenzothiophenes (DBTs), was assessed in nestling tree swallows (Tachycineta bicolor) at mining-related (OS1, OS2) and reference (REF) sites. The OS sites did not receive oil-sands processed waters (OSPW) and were ≥60km from the reference sites. Most of the 42 PACs (≤98%) were detected in all matrices. Swallows at the OS sites were exposed to higher air and water concentrations of individual PAC congeners, ΣPACs, Σparent-PAHs, Σalkyl-PAHs and ΣDBTs. Compared to reference nestlings (ΣPACs: 13-27ng/g wet weight (ww)), PACs were significantly higher in OS nestlings (31-106ng/gww) that also accumulated higher concentrations of major PAHs (i.e., naphthalene, C1-naphthalene, C2-naphthalene, C1-fluorenes, C2-fluorenes, C1-phenanthrenes) measured in 60% of nestlings. Uptake and deposition of PAHs in the birds' muscle was related to diet (δN: C1-naphthalenes, C2-naphthalenes, C1-fluorenes), water (C1-phenanthrenes), and air through inhalation and feather preening (C1-fluorenes), but fecal concentrations were not well explained by diet or environmental concentrations. While PAH concentrations were much higher in muscle than feces, they were highly correlated (p≤0.001 for all). Thus feces may represent a non-lethal method for characterizing PAH exposure of birds, with muscle characterizing accumulation and sources of PAH exposure. Tree swallows in the Athabasca OS Region are exposed to many PACs, accumulating higher concentrations when developing in close proximity to mining activity through diet, aerial deposition and mining-impacted freshwater sources (e.g., wetlands).

Air synthesis review: polycyclic aromatic compounds in the oil sands region

“…This reactive and evolving mixture of PACs is transported in air and ultimately deposited to terrestrial and aquatic systems, thereby initiating the pathways for uptake and accumulation. In the case of air-breathing animals, including humans, the atmosphere is a route for direct inhalation exposure of gas-and particle-associated compounds, which, in the case of birds, results in additional uptake through preening (Fernie et al 2018a).…”

Advances in science and applications of air pollution monitoring: A case study on oil sands monitoring targeting ecosystem protection

“…The concentrations of the six major PAHs measured in nestling tree swallows (ng/g wet weight). Concentrations were similar between the reference birds (REF1, REF2), and significantly higher (P ≤ 0.05) in the birds from the oil sands mining-related sites (OS1, OS2) in the Athabasca oil sands region (Fernie et al 2018a).…”

“…In the OS region, PACs can accumulate in sediments and aquatic insects, resulting in a high exposure potential to PACs for nesting tree swallows that primarily consume aquatic insects (Fernie et al 2018a). In the past, biological responses of tree swallows breeding on reclaimed wetlands in the OS region have been studied (Cruz-Martinez et al 2015;Gentes et al 2007;Godwin, Barclay, and Smits 2019;Harms et al 2010).…”

“…In the past, biological responses of tree swallows breeding on reclaimed wetlands in the OS region have been studied (Cruz-Martinez et al 2015;Gentes et al 2007;Godwin, Barclay, and Smits 2019;Harms et al 2010). During JOSM, colonies of nest boxes for breeding tree swallows were established adjacent to water bodies ( Figure S5.1) at four study sites in 2012 and 2013 (Fernie et al 2018a). Two colonies were located in the surface mining area of the Fort McMurray region, within 5 km of active mining, extraction, and processing (OS sites).…”

“…Two colonies were located in the surface mining area of the Fort McMurray region, within 5 km of active mining, extraction, and processing (OS sites). Two other colonies were established at reference sites, one in 2012 and the other in 2013, more than 100 km from regional OS operations (Fernie et al 2018a).…”