Zero-Valent Sulfur and Metal Speciation in Sediment Porewaters of Freshwater Lakes
Bibliographic record
Abstract
We measured the aqueous solubility of rhombic sulfur and used this information to incorporate, in speciation codes, the thermodynamic constants reported in the literature for the formation of polysulfide complexes. Using the values of pH and total concentrations of dissolved zerovalent sulfur, sulfide, humic substances, trace metals (Ag, Cd, Cu, Hg, methylmercury, Pb, Zn) and major ions measured in anoxic porewaters of nine oligotrophic Canadian lakes as input to these speciation codes, we show that the porewaters of these lakes are undersaturated or close to saturation with respect to rhombic sulfur and that sulfide and polysulfide ligands play a dominant role in controlling metal speciation in freshwater anoxic environments when they are present at micromolar levels. The study also highlights the need for further research on the formation constants of metal complexes with sulfide and polysulfides.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".