COMMENTARY

Unravelling the complexity of pollutionby the oil sands industryDavid W. Schindler1

Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9

Parajulee and Wania (1) make an importantcontribution to understanding the origin andmagnitude of pollution caused by the massive

oil sands industry in northeastern Alberta.Until recently, the oil sands industry and gov-ernment officials have claimed that all pollu-

tants carried by the lower Athabasca Riversystem were the result of soil erosion, forestfires, and other natural phenomena. Thisclaim was challenged by two earlier papersin PNAS (2, 3), which showed that theoil sands industry contributed substantialamounts of organic and inorganic pollu-tants to the watershed and river. Althoughthese conclusions were first denied by indus-try and governments, expert panels appointedby provincial and federal governments sup-ported the results, concluding that industry’sand government’s monitoring programs wereincapable of assessing the extent of the pollu-tion problem (4, 5). As a result, monitoring ofthe river was greatly upgraded by Environ-ment Canada (6).The improved monitoring uncovered

more mysteries. Kelly et al. (2, 3) had foundthat pollutants emitted by the upgraders thatconvert bitumen to synthetic crude oil weredetectable in the winter snowpack of the areato a distance of about 50 km. These resultswere verified by Environment Canada’s stud-ies of snowpack chemistry (7). However,analyses of lake sediments showed that amuch larger area has been contaminatedwith airborne polycyclic aromatic com-pounds (PACs). PACs emanating from theoil sands industry were found in lakes at dis-tances up to 95 km from known sources atbitumen upgraders, and to have increasedover time in proportion to bitumen produc-tion. The “fingerprint” provided by analysisof multiple PACs showed that the oil sandsindustry, not natural sources such as forestfires, was responsible for the increases (8).Parajulee and Wania (1) demonstate a

plausible explanation for the discrepancybetween the magnitude of pollution reportedby ref. 8 and that of refs. 2, 3, and 7. Inwarmer months, emissions of volatile PACsfrom the oil sands industry’s vast tailingsponds (>170 km2 in area, containing 720million m3 of “process water”) (Fig. 1) area major source of PACs to the atmosphere,whereas in winter, cold temperatures and ice

McClelland Lake

Athabasca River

Fort McMurray

0 10 205 km

Imperial Oil's tailings pond

CNRL's tailings pond

Syncrude Canada Ltd.'s tailings pond

Suncor's tailings pond

Fig. 1. An aerial view of the oil sands area in northeastern Alberta.Tailings ponds for major mines have pale yellow labels.Other features of interest have white labels.The Athabasca River (shown) flows from southwest to northeast across Alberta,then flows straight north downstream of Fort McMurray. It terminates in the Athabasca Delta, at the western end of LakeAthabasca, about 250 km downstream of industrial development. Photo courtesy of Peter Lee, Global Forest Watch.

Author contributions: D.W.S. wrote the paper.

The author declares no conflict of interest.

See companion article on page 3344.

1E-mail: d.schindler@ualberta.ca.

www.pnas.org/cgi/doi/10.1073/pnas.1400511111 PNAS | March 4, 2014 | vol. 111 | no. 9 | 3209–3210

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cover on the tailings ponds minimize suchemissions. Their models suggest that by ig-noring emissions from tailings ponds, theannual release of PACs from the oil sandsindustry have been underestimated by asmuch as two orders-of-magnitude. Unfortu-nately, both the official National PollutantRelease Inventory (9) and all previous envi-ronmental impact assessments for oil sandsexpansion in the area (10) have relied on theunderestimated values.The larger PAC deposition field revealed

by Parajulee and Wania (1) also serves asa reminder that more attention must be paidto contamination of regional food sources re-quired by indigenous people in the area. Re-cent studies near the heavy oil industry ineastern Alberta have shown that indigenoususers who rely on terrestrial plants ingestsignificant quantities of contaminants fromindustrial emissions (11). Concentrations ofmercury have also increased substantiallyover the past 30 y in the eggs of fish-eatingbirds downstream of the oil sands industry inthe Athabasca Delta. The only rapidly in-creasing source of the element in the area isemissions from the oil sands industry (2, 3).Increases in birds are paralleled by increasesin naphthalene, also indicating that the likelysource is the oil sands industry (12). Thisparallel suggests that people reliant on fishfor protein may be at increasing risk.Oil sands tailings ponds are still increasing

in area and volume, despite 2009 regulationsthat were designed to reduce them in re-sponse to public concerns. In a 2013 assess-ment of the oil sands industry’s performancein meeting the 2009 standards, the Albertaenergy regulator wrote, “Given the issues thatindustry has encountered, the ERCB [EnergyResources Conservation Board] does not be-lieve that it would be appropriate to enforcecompliance measures at this time” (13). Thenext performance assessment will be in 2015,and the regulator “will assess enforcementoptions at that time” (13). Meanwhile, becauseof the rapid expansion of oil sands mining,the projected volume of tailings is expectedto exceed 1.1 billion m3 by 2020 (14).An incident late last year suggests an even

more serious potential impact of tailingsponds. On October 31, 2013, a dike failure

at the Obed Mountain Coal Mine severalhundred kilometers upstream near Hin-ton, Alberta, discharged 1 million m3

from a tailings pond into the AthabascaRiver. Although the tailings pond was25 km from the river, farther than any of

Parajulee and Waniamake an importantcontribution tounderstanding theorigin and magnitudeof pollution caused bythe massive oil sandsindustry in northeasternAlberta.those in the oil sands (Fig. 1), the tailingsquickly reached the mainstem AthabascaRiver via two tributaries. A visible cloudof tailings was swept downstream, requiringthe closure of water-treatment plants thatdraw water from the river as the toxic cloudpassed and causing great concern from thosereliant on water and fish downstream of

the accident. Unfortunately, the river wasfreezing rapidly at the time of the accidentand a full assessment of environmentaldamage cannot be carried out until springmelt in April 2014. If one of the muchlarger and more toxic oil sands tailingsponds were to suffer a similar spill in win-ter, the tailings would be swept downstreamunder ice for months, entering Lake Atha-basca, the Slave River, Great Slave Lake, andperhaps even the Mackenzie River. Atpresent, there is no effective method forremoving large amounts of spilled oil fromunder river ice, a factor of concern for bothtailings ponds and proposed pipelines tothe Pacific Coast (15). The environmentalimpacts of a large bitumen or tailings spillunder ice on a large river could potentiallyrival those of the Exxon Valdez and Deep-water Horizon spills, threatening water andfood supplies for indigenous people whorely on the river. Unfortunately, the con-sequences of such disasters do not appear tobe considered in oil sands expansion plans.Output is projected to double in the next 10y to 4 million barrels of synthetic crude oilper day.

1 Parajulee A, Wania F (2014) Evaluating officially reported polycyclic

aromatic hydrocarbon emissions in the Athabasca Oil Sands region

with a multimedia fate model. Proc Natl Acad Sci USA

111:3344–3349.2 Kelly EN, et al. (2009) Oil sands development contributes polycyclic

aromatic compounds to the Athabasca River and its tributaries. Proc

Natl Acad Sci USA 106(52):22346–22351.3 Kelly EN, et al. (2010) Oil sands development contributes elements

toxic at low concentrations to the Athabasca River and its tributaries.

Proc Natl Acad Sci USA 107(37):16178–16183.4 Dillon P, et al. (2011) Evaluation of Four Reports on

Contamination of the Athabasca River System by Oil Sands

Operations. Available at http://environment.alberta.ca/documents/

WMDRC_-_Final_Report_March_7_2011.pdf. Accessed January

29, 2014.5 Dowdeswell E, et al. (2010) A Foundation for the Future: Building

an Environmental Monitoring System for the Oil Sands (Environment

Canada, Gatineau, Canada). Available at http://caid.ca/

RepEnvMonOilSan2010.pdf. Accessed January 29, 2014.6 Environment Canada (2011) Lower Athabasca Water Quality

Monitoring Plan Phase I: Athabasca River Mainstem and Major

Tributaries: Minister of the Environment, Government of Canada,

March 22, 2011, Gatineau, QC. Available at www.ec.gc.ca/pollution/

EACB8951-1ED0-4CBB-A6C9-84EE3467B211/Integrated%20Oil%

20Sands_low_e.pdf. Accessed January 30, 2014.7 Kirk J, et al. (2012) Trends in atmospheric deposition of inorganic

contaminants to the Alberta oil sands region obtained from

snowpack and lake sediment core measurements. Abstract, 33rd

Annual SETAC Meeting, Long Beach, CA. Nov. 11–15, 2012.

8 Kurek J, et al. (2013) Legacy of a half century of Athabasca oilsands development recorded by lake ecosystems. Proc Natl Acad SciUSA 110(5):1761–1766.9 National Pollutant Release Inventory (NPRI) (2013) NationalPollutant Release Inventory. Available at www.ec.gc.ca/pdb/websol/querysite/query e.cfm. Accessed December 11, 2013.10 Government of Alberta (2012) Environmental ImpactAssessments. Available at https://external.sp.environment.gov.ab.ca/DocArc/EIA/Pages/default.aspx. Accessed January 6, 2014.11 Irvine G, Doyle JR, White PA, Blais JM (2014) Soil ingestion ratedetermination in a rural population of Alberta, Canada practicinga wilderness lifestyle. Sci Total Environ 470-471:138–146.12 Hebert CE, et al. (2013) Mercury trends in colonial waterbirdeggs downstream of the oil sands region of Alberta, Canada. EnvironSci Technol 47(20):11785–11792.13 Energy Resources Conservation Board (2013) 2012 TailingsManagement Assessment Report: Oil Sands Mining Industry.Available at www.aer.ca/documents/oilsands/tailings-plans/TailingsManagementAssessmentReport2011-2012.pdf. AccessedJanuary 20, 2014.14 Pembina Institute (2013) Backgrounder: Oil Sands Tailings andDirective 074. Available at www.google.ca/search?q=tailings+management+directive+074&oq=tailings+management+directive+074&aqs=chrome.69i57j0l5.12761j0j7&sourceid=. AccessedJanuary 20, 2014.15 Andrishak R, Hicks F (2011) Pipeline rupture under river iceconditions: An assessment of available techniques to mitigateenvironmental impacts. 16th Workshop on River Ice, Winnipeg,Canada Sept. 18–22. Available at http://cripe.civil.ualberta.ca/Downloads/16th_Workshop/Andrishak-Hicks-2011.pdf. AccessedJanuary 21, 2014.

3210 | www.pnas.org/cgi/doi/10.1073/pnas.1400511111 Schindler

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