| Title | Isotopic and microbial evidence for biodegradation of diluted bitumen in the unsaturated zone |
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| Author | Mindorff, L M; Mahmoudi, N; Hepditch, S; Langlois, V S; Alam, S; Martel, R; Ahad, J M E |
| Source | Environmental Pollution vol. 322, 121170, 2023 p. 1-10, https://doi.org/10.1016/j.envpol.2023.121170  Open Access |
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| Year | 2023 |
| Alt Series | Natural Resources Canada, Contribution Series 20220083 |
| Publisher | American Chemical Society |
| Document | serial |
| Lang. | English |
| Media | paper; digital; on-line |
| File format | pdf; html |
| Area | Western Canada; Canada |
| Subjects | fossil fuels; Science and Technology; bitumen; carbon isotopes; pipelines; groundwater |
| Illustrations | graphs; diagrams |
| Program | Environmental Geoscience Environmental impact of diluted bitumen |
| Released | 2023 04 01 |
| Abstract | The oil sands region in Western Canada is one of the world's largest proven oil reserves. To facilitate pipeline transport, highly viscous oil sands bitumen is blended with lighter hydrocarbon fractions
to produce diluted bitumen (dilbit). Anticipated increases in dilbit production and transport raise the risk of inland spills. To understand the behavior of dilbit in shallow groundwater systems following a spill, we ran parallel dilbit and
conventional heavy crude exposures, along with an untreated control, using large soil-filled columns over 104 days. Phospholipid fatty acids (PLFAs), biomarkers for the active microbial population, were extracted from column soil cores. Stable carbon
isotope contents (d13C) of individual PLFAs and radiocarbon contents (D14C) of bulk PLFAs were then characterized. The D14C values in dilbit- (-221.1 per mil to -54.7 per mil) and conventional heavy crude- (-259.4 per mil to -107.1 per mil) impacted
samples indicated similar levels of microbial uptake of fossil carbon. Sequencing of 16S ribosomal RNA genes extracted from soil cores revealed a significant increase in the relative abundance of Polaromonas, a known hydrocarbon-degrader, following
exposure to both types of oil. This study demonstrates that dilbit has a similar potential for biodegradation by a native shallow subsurface microbial community as conventional heavy crude oil. |
| Summary | (Plain Language Summary, not published)
To facilitate pipeline transport, highly viscous bitumen from the Alberta oil sands is blended with lighter hydrocarbon fractions to produce diluted
bitumen (dilbit). Anticipated increases in dilbit production and transport raise the risk of spills into aquifers. To understand the behavior of dilbit in shallow groundwater systems following a spill, we carried out controlled spill experiments in
large soil-filled columns over a 104-day period. Our study has shown that microbial communities in shallow groundwater systems can use dilbit as a carbon source, demonstrating the potential for natural attenuation remediation strategies following a
spill. |
| GEOSCAN ID | 330085 |
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