PARENT SESSION
PT7 - Environmental Forensics: PAHs
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P657) Effects of weathering on the distribution of natural hydrocarbons in the Athabasca Oil Sands, Canada.
Akre, Christine1, Headley, John*,1, Conly, Malcolm2, Peru, Kerry1, Dickson, Leslie1, 1 National Water Research Institue, Saskatoon, Sk, Canada2 Canadian Wildlife Services, Saskatoon, Sk, Canada
ABSTRACT- The Athabasca Oil Sands are one of four natural oil sands deposits in Northern Alberta, Canada, and are by far the largest oil sand deposit in North America, covering an area of 42,000 square kilometers. Bitumen samples taken from various locations in the oil sands area reveal high levels, up to 50 ppm, of alkylated polycyclic aromatic hydrocarbons (PAHs). By the use of double ratio plots of dibenzothiophene/chrysene (D2/C2 vs D3/C3 where the alkyl groups contain 2 and 3 carbons respectively), it is possible to approximate the relative degree of weathering from the different locations. Weathering was more advanced in downstream samples and in the delta compared to upstream tributary samples. Similarly a plot of dibenzothiophene/ phenanthrene (D2/P2 vs D3/P3) indicated possible sources of the oil. A combination of these plots, D3/P3 vs D3/C3, was particularly useful for identification of possible weathering of different sources of the oil. The later plot revealed three different sources of oil within the sampling sites. Comparison of alkylated PAH distributions from the lake/delta region and the tributaries show slight differences consistent with different petrogenic sources and/or different weathering patterns.
Key words: hydrocarbons, weathering, degradation, oilsands