The differential geochemical behavior of arsenic and phosphorus in the water column and sediments of the Saguenay Fjord estuary
Bibliographic record
Abstract
Abstract. The distribution and partitioning of dissolved and particulate arsenic and phosphorus in the water column and sediments of the Saguenay Fjord in Quebec, Canada, are compared. In addition, selective and/or sequential extractions were carried out on the suspended particulate matter (SPM) and solid sediments to contrast their geochemical behaviors in this natural aquatic system. Results of our analyses show that both arsenic and soluble reactive phosphate are actively scav-enged from the water column by settling particles. Upon their accumulation at the sediment-water interface some As and P may be released to porewaters following the degradation of organic matter to which they are associated. The porewater concentrations are, however, limited by their strong affinity for authigenic, amorphous iron oxyhydroxides which accumulate in the oxic sediments near the sediment-water interface. The geochemical behavior of arsenic and phosphorus diverge most strikingly upon the development of anoxic conditions in the sediments. Following their burial in the anoxic zone, amorphous iron oxyhydroxides are reduced and dissolved, releasing phosphate and arsenic to the porewaters. We observed, however, that porewater arsenic concentrations increase at shallower depths than phosphate in the sediments. The reduction of arsenate, As(V), to arsenite, As(III), and its desorption prior to the reductive dissolution of the carrier phase(s) may explain this
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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 | 0.001 | 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 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".