Water and carbon cycles in the Mississippi River basin: Potential implications for the Northern Hemisphere residual terrestrial sink
Bibliographic record
Abstract
The hydrologic cycle plays an important role in carbon cycling, due to the coupling of vapor release and CO2 uptake during photosynthesis. This coupling, expressed as Water Use Efficiency (WUE) or Transpiration Ratio, can provide an inexpensive alternative for estimating the Net Primary Productivity (NPP) of terrestrial ecosystems. The D/H and 18O/16O trends of river water in the Mississippi basin are mostly indistinguishable from those of precipitation. This, combined with isotopic mass balance relationships, suggests that direct evaporation of surface water is small and evapotranspiration (ET) flux from the basin therefore consists mostly of interception and transpiration, with interception approximated from field studies. The calculated water flux associated with transpiration is 1500.8 km3 (77.3% of the evapotranspiration flux). Utilizing the average WUE of 864 mol H2O for each mole of CO2, the NPP of the Mississippi River basin amounts to 1.16 Pg C/yr, similar to the model estimates of the heterotrophic soil respiration flux of 1.12 Pg C/yr. This does not favor the postulated existence of a major sink for atmospheric CO2 in the temperate Northern Hemispheric ecosystems of the conterminous United States, but due to uncertainties in the input parameters we cannot discount the possibility that these ecosystems act as a modest sink.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".