A landscape limnology approach to assessing controls on soluble reactive phosphorus in sediment porewater and internal loading risk
Bibliographic record
Abstract
Sediment nutrients can be mobilized to overlying water via internal loading, which can be important to aquatic productivity. Using data from 143 Canadian lakes, we show high (~2400-fold) variation of soluble reactive phosphorus (SRP) concentrations in surficial sediment porewater, with results suggesting internal phosphorus loading (IPL) is also likely to vary widely. Consistent with past work at smaller scales, we show that lake depth, pH, trophic status, and bulk sediment Al:P and Fe:P influence porewater SRP, and IPL. Median porewater SRP concentration in lakes with high Al:P (molar ratios >10) were 4.8-fold smaller than in lakes with lower Al:P. In lakes where bulk sedimentary Fe:P molar ratios were >10 porewater SRP was 3.9-fold lower than in lakes with lower Fe:P. High pH (>7.8), along with hyper-eutrophic lakes were associated with higher porewater SRP. Finally, shallow lakes (<4 m depth) had median porewater SRP concentration 6-fold higher than deep lakes (>9 m depth). Important regional differences emerged, linked to regional variation in pH, soils, lake depth and trophic status, and paralleling areas of poor water quality. For example, median porewater SRP in lakes from the Boreal Plains and Prairies ecozones (dominated by Chernozems/Mollisols) was 64-fold and 44-fold higher than in the Boreal Shield (dominated by Podzols/Spodosols) (respectively), although we note that IPL risk is likely important across many ecozones. Using national data, we found in-lake measurements (particularly pH, and salinity) showed strong capacity in predicting porewater SRP (explaining 60-72 % of the variance in the data). Importantly, watershed predictors showed good predictive power, explaining ~50 % of variance in porewater SRP using variables including soil types, and % agriculture. Porewater SRP can be predicted with reasonable accuracy using easily measured variables, as can estimates of internal phosphorus loading, suggesting that landscape limnology holds strong potential in helping to inform lake management by informing understanding of in-lake nutrient sources.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".