Mercury cycling in hydroelectric reservoirs of northern Manitoba decades after impoundment
Bibliographic record
Abstract
As the global climate changes and demand for renewable electricity increases, construction of hydroelectric dams is increasing globally though the impacts of regulating the worlds rivers are still understudied. Northern Manitoba, Canada, has extensive hydroelectric development since the 1950s; fish mercury (Hg) concentrations in on-system lakes were observed to have increased above human consumption guidelines upon impoundment and have taken decades to decrease towards natural concentrations. To better understand the long-term impacts of hydroelectric regulation on Hg in fish and other biota in Northern Manitoba, we determined methylmercury (MeHg) production potential in soil from the water fluctuation zone in on- and off-system lakes through a soil flooding incubation experiment in the laboratory. We further studied the historic flux of MeHg and Hg to the sediments in on- and off-system lakes and links to organic matter in these waterbodies. We found that MeHg production was highest in the water fluctuation zone of the on-system lakes, which may represent an increased source of MeHg to the food web in these environments even decades after impoundment. In addition, sedimentation rates were found to greatly affect Hg fluxes to the sediment in those waterbodies where increased water flows result in higher erosion and sedimentation. These findings provide new insight in our understanding of the long-term recovery of Hg cycling within on-system lakes decades after impoundment.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".