New Study Finds That Oil Sands Development a Greater Source of Contamination Than Previously Realized; Challenges Existing Monitoring Program
A study by researchers in Canada and the US shows that oil sands development is a greater source of polycyclic aromatic compound (PAC) contamination to the Athabasca River and its tributaries than previously realized. The study was published online 7 December as an open access paper in the Proceedings of the National Academy of Sciences (PNAS) of the US.
Bitumen production in the Alberta oil sands has increased rapidly, rising from 482,000 to 1.3 million barrels per day from 1995 to 2008; output is projected to reach 2.0 to 2.9 million barrels per day by 2020. Despite the claims of some residents in the area that the oil sands industry is responsible for higher than expected cancer rates, the government-industry Regional Aquatic Monitoring Program (RAMP) has reported that effects are minimal, and that human health and the environment are not at risk. The new study directly challenges the RAMP findings, and calls for a major redesign of the program.
Our study confirms the serious defects of the RAMP. More than 10 years of inconsistent sampling design, inadequate statistical power, and monitoring-insensitive responses have missed major sources of PAC to the Athabasca watershed. Most importantly, RAMP claims that PAC concentrations are within baseline conditions and of natural origin have fostered the perception that high-intensity mining and processing have no serious environmental impacts.
The existing RAMP must be redesigned with more scientific and technical oversight to better detect and track PAC discharges and effects. Oversight by an independent board of experts would make better use of monitoring resources and ensure that data are available for independent scrutiny and analyses. The scale and intensity of oil sands development and the complexity of PAC transport and fate in the Athabasca watershed demand the highest quality of scientific effort.
—Kelly et al.
The researchers conducted a detailed assessment of the loadings of PAC to the north-flowing Athabasca River, its tributaries, the Athabasca Delta, and Lake Athabasca. They sampled water and accumulated snowpack. Sampling sites were selected upstream and downstream of oils sands mining and processing activity.
Samples were analyzed for PAC. Melted snow was analyzed for the mass of particulate and associated PAC retained on glass fiber filters, and for dissolved PAC in filtrate. Among the findings were:
Within 50 km of oil sands upgrading facilities, the loading to the snowpack of airborne particulates was 11,400 T over 4 months and included 391 kg of polycyclic aromatic compounds (PAC), equivalent to 600 T of bitumen, while 168 kg of dissolved PAC was also deposited.
Dissolved PAC concentrations in tributaries to the Athabasca increased from 0.009 µg/L upstream of oil sands development to 0.023 µg/L in winter and to 0.202 µg/L in summer downstream.
In the Athabasca, dissolved PAC concentrations were mostly <0.025 µg/L in winter and 0.030 µg/L in summer, except near oil sands upgrading facilities and tailings ponds in winter (0.031–0.083 µg/L) and downstream of new development in summer (0.063–0.135 µg/L).
In the Athabasca and its tributaries, development within the past 2 years was related to elevated dissolved PAC concentrations that were likely toxic to fish embryos. In melted snow, dissolved PAC concentrations were up to 4.8 µg/L, thus, spring snowmelt and washout during rain events are important unknowns.
Due to substantial loadings of airborne PAC, the oil sands industry is a far greater source of regional PAC contamination than previously realized. Despite previous recommendations, there is no apparent detailed monitoring of PAC fluxes via wet and dry deposition in the winter or summer, when similar or greater contributions are likely. Monitoring of air, the snowpack, spring snowmelt, and summer rain and vegetation is essential to identify and control sources of PAC and their potential environmental and human health impacts. A second important source of PAC is landscape disturbance. Surprisingly, impacts are related primarily to recent disturbance (<2 y), which suggests that re-vegetation or erosion controls mitigate long-term loadings.
Controls on waterborne PAC are critical because concentrations at tributary mouths and at one site on the Athabasca are already within the range toxic to fish embryos. However, the impacts on the Athabasca ecosystem of mining wastewater, snowmelt, or contaminated groundwater remain enigmatic due to high seasonal variability of flow and dilution capacity.
—Kelly et al.
Erin N. Kelly, Jeffrey W. Short, David W. Schindler, Peter V. Hodson, Mingsheng Ma, Alvin K. Kwan, and Barbra L. Fortin (2009) Oil sands development contributes polycyclic aromatic compounds to the Athabasca River and its tributaries. PNAS doi: 10.1073/pnas.091205010