Competitive dissolution of mixed carbonate solids under simulated ocean acidification
Bibliographic record
Abstract
It is estimated that at least 25 % of the anthropogenic carbon dioxide (CO 2 ) emitted to the atmosphere since the start of the industrial revolution has been absorbed and dissolved by the oceans. The uptake of CO 2 by the oceans leads to an increase in the seawater proton concentration ([H + ]), and decreases in seawater pH, carbonate ion concentration ([CO 3 2– ]), and saturation state (Ω) with respect to calcium carbonate (CaCO 3 ) minerals; a process commonly referred to as “ocean acidification”. Shallow-water (<200 m), high-magnesium, biogenic calcites are expected to be amongst the first to respond to ocean acidification, and it has been proposed that they will dissolve selectively and sequentially according to their solubility in seawater. In this study, we test this competitive dissolution hypothesis by reacting a mixture of biogenic and synthetic carbonates of varying Mg content with acidified, natural seawater to simulate the progressive acidification of surface-ocean waters by anthropogenic CO 2 . The results of this study confirm the hypothesis that carbonates will dissolve sequentially according to their respective solubility. They also reveal that the dissolution of high Mg-calcites will proceed incongruently. The originality of this contribution rests with the demonstration that the presence of a single high Mg-calcite will generate, like in a sediment of mixed mineralogy, a continuum of transient states as lower Mg-calcites of greater stability are precipitated and dissolved. Consequently, in a semi-closed or closed system, the pH buffering of the acidified seawater solution will be progressive rather than occur in steps according to changes in the solubility of the individual carbonate phases that compose a sediment. Hence, we expect that, as the oceans take up more anthropogenic CO 2 and further acidify, the average mineralogy and composition (Mg content) of shallow-water carbonate sediments and reef structures will change over the next few centuries as the most soluble carbonate phases (high-Mg calcites) are dissolved and no longer precipitated.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".