Environmental controls of the seasonal variation in oxygen uptake in sulfidic tailings deposited in a permafrost‐affected area
Bibliographic record
Abstract
Oxygen consumption, sulfide oxidation, and acid mine drainage (AMD) of pyritic mine tailings were investigated at Nanisivik Mine, which is located in an area with continuous permafrost on Baffin Island in northern Canada. Tailings of varying age and water content have been deposited under alkaline conditions. One area consisting of tailings deposited on land in 1992 was selected for detailed measurements of in situ oxygen uptake rates at the tailing surface in the summers 1998 and 1999 and periodically during autumn and winter in 1998. Measurements included oxygen gas, water content, and temperature in profiles, as well as chemical analyses of pore solution and solids. Additional oxygen consumption rates were measured under controlled temperature conditions on columns filled with partly oxidized tailings. On the basis of temperature dependency of pyrite oxidation observed in the laboratory, an Arrhenius diffusion equation with soil temperature as input was used to simulate the observed temporal variation in oxygen uptake. Field data reveal that the ongoing sulfide oxidation of well‐drained tailings primarily takes place in the upper 30 cm and that oxidation has resulted in a depletion of pyrite, carbonates, and metals from this reaction zone. The model provides a reasonable fit to the observed trend in oxygen consumption and documents that oxidation of sulfide minerals in tailings is not reduced to neglectable levels at O°C. The AMD generation rate has been quantified based on the changes in concentration of oxidation products in the pore water and oxidation rates based on in situ measurements of oxygen consumption. The two rate descriptions provide comparable estimates of seasonal AMD generation and provide detailed information on weather‐related controls of AMD generation, i.e., ground temperature, freezing, water content, and snow cover. These environmental controls are crucial for the design of frozen cover schemes in permafrost regions, where the aim is to force the frost table to the top of the tailings, maintaining tailings at subzero temperatures year‐round and thereby controlling the AMD generation.
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How this classification was reachedexpand
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 | 0.001 | 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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 teacher head, 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".