Periphyton biomass response to changing phosphorus concentrations in a nutrient-impacted river: a new methodology for phosphorus target setting
Bibliographic record
Abstract
Nutrient modification experiments were conducted in streamside flumes to determine the concentration at which P limits algal growth in the mesotrophic River Frome, Dorset, UK. The soluble reactive P (SRP) concentration in each flume was either increased (by P addition), decreased (by precipitating P with iron(II) sulphate solution), or left unaltered (control), producing SRP concentrations ranging from 32 to 420 µ·L–1. Increasing the ambient SRP concentration did not increase epilithic algal growth, showing that the River Frome was not P limited at 109 µ SRP·L–1. In the P-stripped flumes, algal biomass declined as the SRP concentration fell below ~90 µ·L–1, with a 60% biomass reduction at <40 µ SRP·L–1. Phosphorus-diffusing periphytometers deployed in the P-stripped flumes confirmed that reduced rates of algal growth were due to P limitation rather than a physical effect of FeSO4 addition. The ~90 µ·L–1 maximum P-limiting concentration is likely to be similar for comparable nutrient-impacted rivers. This iron-stripping approach expands the existing river nutrient-enrichment methodology so that it can be used in nutrient-impacted rivers and should allow catchment managers to produce knowledge-based P reduction targets prior to introducing remediation.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".