25th International Meeting on Organic Geochemistry IMOG 2011

P-389
Biogeochemical process studies on oil sand tailings used for
land reclamation
Mareike Noah 1 , Andrea Vieth-Hillebrand 1 , Beate Schneider 2 , Bernd Uwe Schneider 1 ,
Heinz Wilkes 1
1 Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam,
14473, Germany, 2 University of Potsdam, Karl-Liebknecht-Strasse 24-25, Potsdam, 14476, Germany
(corresponding author:noah@gfz-potsdam.de)
The Athabasca region of northern Alberta, Canada, is
home to deposits of oil sands containing vast
amounts (~ 173 billion barrels) of heavily biodegraded
petroleum, known as bitumen.
Oil sands are recovered by surface mining or by in
situ steam injection. The extraction of bitumen from oil
sands by caustic hot water processing results in large
volumes of fluid tailings, which are stored in on-site
settling basins. There the tailings undergo a
compaction and dewatering process, producing a
slowly densifying suspension. The released water will
be recycled for extraction. The fine tailings will be
reclaimed as either dry or wet landscapes. [1]
Oil sands are the result of very intense anaerobic
biodegradation processes that occurred since
expulsion of oil from the source rock and have been
controlled by temperature and the presence of water
and nutrients. Also after oil sands extraction
anaerobic biodegradation will occur within the tailing
ponds leading to a release of greenhouse gases into
the atmosphere. Anaerobic biodegradation of
hydrocarbons to end products like methane and
carbon dioxide is possible by different groups of
microorganisms: denitrifying bacteria, sulfate-reducing
bacteria and methanogens. [2]
Open pit mining and the extraction of the bitumen
from the oil sands creates large and intense
disturbances of varying landscapes. The area
currently disturbed by mine operation covers about
530 km 2 and the area of tailing ponds surpasses
130 km 2 .
To produce 1 barrel of crude oil, 2 tons of oil sand and
2 – 3 tons of water (including recycled water) are
required. [3]
An issue of increasing importance is the land
remediation and reclamation of oil sand areas in
Canada and coal mining sites in Germany and the
reconstruction of these disturbed landscapes back to
working ecosystems similar to those existing prior to
disturbance.
For that reason the identification of oil sand-derived
organic compounds in the tailings, their environmental
behaviour and the resulting chances and limitations
are key topics for land reclamation. Furthermore the
biodegradation processes that occur in the tailings
and that could lead to a decrease in hazardous
organic compounds are important challenges, which
need to be investigated.
This presentation will give a detailed overview of our
compositional and quantitative characterisation of
organic matter in oil sand, coal and oil sand tailing
samples. The analytical characterisation is based on
the extraction of the soluble organic matter, its
subsequent separation into asphaltenes, aliphatics,
aromatics, neutral NSO (nitrogen, sulphur, oxygen)
compounds and fatty acids. The asphaltene fractions
are analysed using Pyrolysis-GC, all other fractions
are analysed by GC-MS. Furthermore, details of
biogeochemical processes will be elucidated by
establishing an inventory of phospholipids and
biomarkers as well as determining the carbon and
hydrogen stable isotopic composition of individual
organic compounds.
References
1. Leung, S.S.-C., MacKinnon, M.D., and Smith, R.E.H.,
Aquatic reclamation in the Athabasca, Canada, oil
sands: Naphthenate and salt effects on phytoplankton
communities. Environmental Toxicology and Chemistry,
2001. 20(7): p. 1532-1543.
2. Salloum, M.J., Dudas, M.J., and Fedorak, P.M.,
Microbial reduction of amended sulfate in anaerobic
mature fine tailings from oil sand. Waste Management &
Research, 2002. 20(2): p. 162-171.
3. Kelly, E.N., et al., Oil sands development contributes
polycyclic aromatic compounds to the Athabasca River
and its tributaries. Proceedings of the National Academy
of Sciences, 2009. 106(52): p. 22346-22351.
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