Diffusive boundary layers do not limit the photosynthesis of the aquatic macrophyte, Vallisneria americana, at moderate flows and saturating light levels
Bibliographic record
Abstract
Hydrodynamic models of mass transport assume that diffusive processes next to the surface limit transport and that there are no biological and chemical processes that control the supply and demand of the scalar. The validity of these assumptions was examined by measuring the momentum boundary layer (via particle image velocimetry) and the concentration boundary layer (via O2 microsensors) over the leaves of Vallisneria americana. The O2 flux (Jobs) was highest at x = 2 cm downstream from the leading edge of the leaf and was 1.8 to 1.4 times higher than Jobs measured at the trailing edge of the leaf at 0.5 cm s−1 and 6.6 cm s−1 mean velocity (U), respectively. The maximum Jobs was 0.44 ± 0.07 (mean ± SE) vs. 0.50 ± 0.09 µmol m−2 s−1 at 0.5 vs. 6.6 cm s−1. Interestingly, the surface O2 potential (D[O2] = [O2]surface ‐ [O2]bulk) was also unimodal at the low velocity (D[O2]max = 36 ± 5 mmol m−3 at x = 3 cm) but was uniform at the higher velocity (D[O2] = 9 ± 0.7 mmol m‐3). An analysis of the time scale of nutrient diffusion (τD) vs. nutrient uptake (τup) through the measured diffusion boundary layer revealed that uptake was always the slower process (i.e., τD < τup; τD and τup increased with x and decreased with U). Under moderate water velocities and saturating irradiance, uptake rates rather than diffusive transport processes appear to control mass transfer rates regardless of the location on the leaf and the water velocity.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".