METHANE BIOGEOCHEMICAL CYCLING OVER SEASONAL AND ANNUAL SCALES IN AN OIL SANDS TAILINGS END PIT LAKE
Bibliographic record
Abstract
This Master’s degree study examined concentration and isotopic trends of dissolved methane, isotopic trends of phospholipid fatty acids (PLFA), and generated 1st order flux calculations to identify and assess biogeochemical cycling of dissolved methane in the first full-scale demonstration of EPL technology in the Alberta Oil Sands Region (AOSR). Base Mine Lake (BML) was commissioned by Syncrude Canada Ltd. in 2012 to facilitate the long-term storage and remediation of Fluid Fine Tailings (FFT) that are generated as a result of bitumen extraction via the Clark Hot Water Extraction (CHWE) processes. The results of this project provide evidence of methane oxidation by type I methanotrophs in BML, reducing dissolved oxygen concentrations in the hypolimnion layer. The FFT layer is identified as a source zone of fermentative methanogenesis, creating saturated conditions of dissolved gases. Dissolved methane is transferred to the water column primarily by advective processes related to FFT consolidation, while diffusion is a significant secondary transfer mechanism. Dissolved methane concentrations decrease significantly across the FFT-water interface where diffusive flux rates decrease by several orders of magnitude. Concentrations decreased linearly through the hypolimnion to trace concentrations by the metalimnion, resulting in a minor enrichment of δ13C of the residual dissolved methane pool. A minor enrichment of δ13C in C14:0, C16:0, and C16:1 PLFA coincided across the same interval, indicating utilization of a less depleted carbon source further away from the FFT-water interface where dissolved methane concentrations were lower. PLFA δ13C signatures were depleted relative to expected values of typical DOC substrates, further supporting the incorporation of a depleted signature by transfer of depleted carbon from dissolved methane.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".