Detection and characterisation of groundwater discharge into lakes
Bibliographic record
Abstract
The aims of this study are. twofold. Our first aim is to locate groundwater discharge into lakes through mineralised Precambrian rock structures in the Canadian Shield. Groundwater is known to contribute to the water balance of lakes in the study area, but the exact location and volume of groundwater discharge is not well understood. Secondly, we aim to characterise this groundwater, both as regards its upgradient mineral content and subsequent chemical behaviour in the lake water. Detection of the groundwater was done close to the sediment-water interface using a water quality multiprobe to measure conductivity, pH, Eh, dissolved oxygen (DO), turbidity, temperature and depth. The presence of groundwater was deduced from in-situ DO and conductivity readings and subsequent chemical analysis of water samples for major cations and trace metals. A Differential GPS was used to record the location of the multiprobe to within 3 metres accuracy. Lake bottom depths were measured simultaneously. In general, bottom waters are oxygenated, even at depths greater than 100 metres. Dissolved silica concentrations in the photic zones of the lakes are comparable to those in surface ocean water (about 0.1 ppm), indicating the presence of diatoms. Inverse correlation between DO and silica concentrations - low DO and high silica - indicates groundwater discharge. Stagnant lake water with low DO is differentiated from groundwater on the basis of conductivity and dissolved silica, which are higher in groundwater. Groundwater emerging from eskers below the lake surface is differentiated from groundwater emerging from Precambrian rocks on the basis of higher dissolved calcium and sodium content in groundwater from eskers. About half of the bottom sites with low DO contain detectable H2S and have Eh levels close to the sulfide-sulfate boundary. Trace metals in the groundwater showed a variation in reactivity to both H2S and DO as they discharge into and mix with lake water. Dissolved iron concentration, for instance, varies inversely with DO, but is apparently unaffected by H2S. Dissolved copper is decreased to below 0.3 ppb by reaction with H2S, but is not effected by DO. Vanadium mobility is greatest under the most reducing conditions measured. These and other measurements indicate that trace metal reactions can be followed as the groundwater mixes with lake water.
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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 | 0.000 | 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) | 0.000 | 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 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".