Biodegradation of Short-Chain <i>n</i>-Alkanes in Oil Sands Tailings under Methanogenic Conditions
Why this work is in the frame
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Bibliographic record
Abstract
The biodegradation of a mixture of low molecular weight n-alkanes (C6, C7, C8, and C10) was assessed under methanogenic conditions using mature fine tailings (MFT) produced by the oil sands industry in Alberta, Canada. Microorganisms present in the MFT mineralized the added n-alkane mixture, producing 16.2 (+/- 0.3) or 20.5 (+/- 0.1) mmol of methane in the headspace of microcosms spiked with 0.2% or 0.5% w/v n-alkanes, respectively, during 29 weeks of incubation. The spiked n-alkanes biodegraded in the sequence C10 > C8 > C7 > C6. Degradation of 100% C10, 97% C8, 74% C7, and 44% C6 occurred in a mixture of n-alkanes in the MFT spiked at 0.2% after 25 weeks of incubation. The same pattern of biodegradation was also observed in the MFT spiked with 0.5% n-alkanes. Stoichiometric calculations confirmed the mineralization of the degraded n-alkanes to methane. This study showed that the short-chain n-alkanes, which comprise a significant portion of the unrecovered naphtha used in bitumen extraction and released into the settling basins, can be biodegraded into methane. These findings may influence decisions regarding extraction processes and long-term management of MFT, and they suggest that intrinsic, methanogenic metabolism of these n-alkanes may occur in other anoxic environments.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it