Sulfur oxidation and implications for oxygen consumption in Base Mine Lake, the first pilot oil sands pit lake in the Athabasca oil sands region
Bibliographic record
Abstract
Base Mine Lake (BML) is the first pilot scale oil sands pit lake in the Athabasca Oil Sands Region (AOSR). Following a whole lake alum addition in September of 2016, a seasonally recurring zone of anoxia developed in the late summer hypolimnion of the BML water cap. The extent to which sulfur cycling exacerbates or mitigates this phenomenon in BML remains unclear. The objective of this 7–year was to characterize the identity and function of the sulfur oxidizing bacteria (SOB) and determine SOB risks to oxygen consumption in BML. The study revealed a persistent community of SOB that collectively encoded the genes involved in the primary sulfur oxidation pathways (Sox, rDSR, and S 4 I). The majority of SOB in BML have been previously identified as heterotrophs, allowing for metabolic flexibility depending on geochemical conditions that varied seasonally. The relative abundance of SOB genera comprising this community shifted as a result of the alum addition and has yet to stabilize over time. Simultaneous consumption of thiosulfate and nitrate was observed in the summer hypolimnion of BML post-alum, consistent with anaerobic sulfur oxidation. Furthermore, the anoxic zone occupied the largest portion of the hypolimnion when anaerobic sulfur oxidation was limited, suggesting it had a mitigating effect on anoxic zone expansion through removal of reduced sulfur species via nitrate driven sulfur oxidation by SOB. Constraining biological impacts to oxygen consumption in this pilot OSPL will be key to managing the growing tailings inventory of the AOSR as another ~23 OSPLs are proposed pending the outcome of BML.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".