Combined analyses of O<sub>2</sub> and CO<sub>2</sub> for studying the coupling of photosynthesis and respiration in aquatic systems
Bibliographic record
Abstract
To simultaneously elucidate patterns of photosynthesis and respiration in aquatic systems, we developed a new gas-switching system for coupled measurements of dissolved metabolic gases. The methodology involves two gas chromatography columns to perform multiple gas separations. The first example using 24 h bottle incubations in estuarine waters showed a 1:1 molar relationship for the coupling between CO2 and O2 in closed systems during photosynthesis and respiration. In a second, open system application using depth-stratified sampling on the Louisiana continental shelf, deviations from this 1:1 relationship between CO2 and O2 were common. In surface waters, depletion of CO2 exceeded excess O2, likely owing to different gas-exchange rates with the atmosphere. In bottom waters, CO2 accumulation could surpass O2 losses, indicating anaerobic respiration. At intermediate depths, CO2 and O2 dynamics followed the 1:1 relationship that was observed in the closed incubations. This approach clearly showed that CO2 and O2 dynamics were tightly coupled on short-time scales, but anaerobic respiration and physical processes such as gas exchange can lead to strong divergence of CO2 and O2 stoichiometries. This combined analysis of respiratory gases that is readily achievable with isotope ratio mass spectrometer systems illustrates how oxygen and carbon cycles are coupled and decoupled in aquatic systems.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".