Sulfate Mobility in Fen Peat and Its Impact on the Release of Solutes
Bibliographic record
Abstract
Sea-level rise coupled with land subsidence from wetland drainage exposes increasingly large areas of coastal peatlands to seawater intrusion. Seawater contains high concentrations of sulfate (SO42-), which can alter the decomposition of organic matter thereby releasing organic and inorganic solutes from peat. In this study, a flow-through reactor system was used in order to examine the transport of SO42- through peat as well as its effect on solute release. Moderately-decomposed fen peat samples received input solutions with SO42- concentrations of 0, 100, 700 and 2700 mg L-1; sample effluent was analyzed for a variety of geochemical parameters including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and total dissolved nitrogen (TDN) as well as the concentrations of major cations and anions. The input solution remained anoxic throughout the experiment; however, no signs of a pronounced SO42- reduction were detected in the effluent. SO42- transport in the fen peat resembled non-reactive bromide (Br-) transport, indicating that in the absence of SO42- reduction the anion may be considered a conservative tracer. However, slightly elevated concentrations of DOC and TDN, associated with raised SO42- levels, suggest the minor desorption of organic acids through anion exchange. An increased solute release due to stimulated decomposition processes, including SO42- reduction, was observed for samples with acetate as an additional marine carbon source included in their input solution. The solute release of peats with different degrees of decomposition differed greatly under SO42--enriched conditions where strongly-decomposed fen peat samples released the highest concentrations of DOC, DIC and TDN. Overall, besides a cation-exchange related release of substances adsorbed in the peat, an input of increased SO42- concentrations in a peatland by itself might not lead to an increased solute release in the short-term. However, once SO42- reduction has commenced following long-term anoxic conditions or due to a biologically readily degradable carbon source, a SO42- input can stimulate the release of solutes, including DOC, DIC and TDN, from peat.
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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 | 0.000 | 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) | 0.000 | 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".