Legacy of a half century of Athabasca oil sands development recorded by lake ecosystems

Abstract

The absence of well-executed environmental monitoring in the Athabasca oil sands (Alberta, Canada) has necessitated the use of indirect approaches to determine background conditions of freshwater ecosystems before development of one of the Earth’s largest energy deposits. Here, we use highly resolved lake sediment records to provide ecological context to ∼50 y of oil sands development and other environmental changes affecting lake ecosystems in the region. We show that polycyclic aromatic hydrocarbons (PAHs) within lake sediments, particularly C1-C4–alkylated PAHs, increased significantly after development of the bitumen resource began, followed by significant increases in dibenzothiophenes. Total PAH fluxes in the modern sediments of our six study lakes, including one site ∼90 km northwest of the major development area, are now ∼2.5–23 times greater than ∼1960 levels. PAH ratios indicate temporal shifts from primarily wood combustion to petrogenic sources that coincide with greater oil sands development. Canadian interim sediment quality guidelines for PAHs have been exceeded since the mid-1980s at the most impacted site. A paleoecological assessment of Daphnia shows that this sentinel zooplankter has not yet been negatively impacted by decades of high atmospheric PAH deposition. Rather, coincident with increases in PAHs, climate-induced shifts in aquatic primary production related to warmer and drier conditions are the primary environmental drivers producing marked daphniid shifts after ∼1960 to 1970. Because of the striking increase in PAHs, elevated primary production, and zooplankton changes, these oil sands lake ecosystems have entered new ecological states completely distinct from those of previous centuries.

Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada

“…SML and SUN are known to use naphtha additives as solvents to expedite the separation, whereas SAJ, SAU, and IKL use paraffinic solvents (36,38). Both types of solvents contain various portions of paraffinic hydrocarbons with carbon numbers around C 6 as the effective ingredients; naphtha solvents have higher carbon alkanes (>C 6 ) and high aromatic content, whereas paraffinic solvents tend to have lower carbon alkanes (≤C 6 ) and much less aromatics (36,38). The VOC profiles in the measured air emissions reflect such differences: for SML and SUN, the aromatics account for 19 and 15% of aE, respectively, whereas the ≤C 6 and >C 6 alkanes account for 13.0 and 36.9% at SML and 25.3 and 35.3% of aE at SUN, respectively.…”

“…The surface mining facilities are large in size, each encompassing an area of 66-275 km 2 and consisting of complex activities from ore mining, bitumen and sand separation, and upgrading to tailings management (5). Development on such large scales has increased concerns of its environmental impacts (6)(7)(8), including on air quality and human health. Key concerns are the amount and type of pollutants emitted into the environment and the accuracy of the emission reports (8).…”

Evaluating officially reported polycyclic aromatic hydrocarbon emissions in the Athabasca oil sands region with a multimedia fate model

“…14-16), and the difficulty in ascribing observed environmental residue levels to natural sources versus anthropogenic activity. However, a recent assessment of PAHs in lakesediment cores provides compelling evidence that oil sands development has led to a significant increase in PAH levels in the AOSR environment (17). Although there have been studies providing insight into concentrations of PAHs in air (18), water (13), snow (13), sediments (10,17,(19)(20)(21), tailings pond pore water (22), and tailings pond sediments (10,21) in the AOSR, thorough characterization of PAH sources, pathways, and sinks within the AOSR is still lacking.…”

False Promises: The contours, contexts and contestation of good water governance in Lao PDR and Alberta, Canada

“…In 1997, the Regional Aquatic Monitoring Program (RAMP) was established as a multi-stakeholder platform for determining the effects of oil sands development. But the program was widely indicted for lacking scientific rigor and independent tests that found, contra RAMP, that oil sands activity degraded water quality (Ayles, Dubé & Rosenberg 2004, Kelly et al 2009, Kurek et al 2013). …”