Kinetics of manganese adsorption, desorption, and oxidation in coastal marine sediments
Bibliographic record
Abstract
Ejection of excavated manganese (Mn)‐laden particles from anoxic subsurface sediment onto an oxic sediment‐water interface by infauna and by other physical disturbances triggers desorption and oxidation of reduced manganese species. These competing reactions determine whether adsorbed Mn(II) will be desorbed and escape into the water column or be oxidized to Mn(IV) and retained as an insoluble component of the sediment. Consequently, the net flux of Mn(II) to the water column depends on the relative rates of the two reactions. We determined the rates of Mn(II) adsorption, desorption, and oxidation by incubating slurries of natural anoxic sediment at 25°C and monitoring the concentration of manganese in the aqueous phase of the slurry. The kinetics of adsorption, desorption, and oxidation were fitted to first‐order rate laws. The first‐order rate constants for adsorption ( = 7.0 ± 3.4 h −1 ) and desorption ( = 12.7 ± 3.3 h −1 ) are more than two orders of magnitude greater than the first‐order rate constant for oxidation ( = 0.020 ± 0.006 h −1 ). The combination of rapid desorption kinetics and slow oxidation kinetics allows dissolved manganese to be dispersed into the bottom water by turbulent diffusion and escape local reoxidation and retention at the sediment‐water interface. Thus, advection of anoxic sediment to the sediment‐water interface contributes to the overall flux of manganese from the sediment to the water column.
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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 | 0.000 | 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 | 0.000 |
| 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 teacher head, 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".