Calcite dissolution kinetics at the sediment-water interface: An experimental study in natural seawater at 25°C
Bibliographic record
Abstract
Ocean acidification, in response to rising anthropogenic CO 2 concentration in the atmosphere, will lead to both a decrease in seawater pH, biogenic calcification and an increase in carbonate mineral dissolution in marine sediments.CaCO 3 -rich sediments, which cover nearly a third of the ocean floor, will serve as the ultimate sink of the anthropogenic CO 2 delivered to the deep-ocean.Nevertheless, factors that control the kinetics of the CaCO 3 dissolution reaction under conditions encountered at the sediment-water interface have not been properly parameterized.In this study, we investigated the dissolution kinetics of a simulated, organic-free, calcite-rich sediment in natural seawater at 25C and one atmosphere total pressure under controlled hydrodynamic conditions.Dissolution rates were measured in a flow-through system at various undersaturations using a specially-designed stirrer that generated a nearly uniform shear at the sediment-water interface.Measured calcite dissolution rates normalized to the exposed interface area were linearly dependent on the undersaturation of the seawater with respect to calcite (1- C ).Although the reaction order (n = 1.24 0.93) is lower than most of those obtained from laboratory experiments with fully resuspended sediments or calcite particles, the rate constant, k, is similar to those determined in previous studies.The dissolution rates measured close to equilibrium (1- C 0.2) were independent of the stirring rate over the range investigated and, thus, we believe that calcite dissolution must be surface-reaction controlled or controlled by the diffusion rate out of the sediment under our experimental conditions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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; both teacher heads agree on what is shown here.
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".