Saturated and unsaturated salt transport in peat from a constructed fen
Bibliographic record
Abstract
Abstract. To determine the underlying processes of solute transport in peat an experimental constructed fen peatland, soil hydraulic properties were measured and saturated and unsaturated solute breakthrough experiments were performed using Na+ and Cl− as reactive and non-reactive solutes, respectively. We tested the performanceof three solute transport models, including the classical equilibrium Convection-Dispersion Equation (CDE), a chemical non equilibrium one-site adsorption model (OSA) and a model to account for physical non-equilibrium, the mobile-immobile phases (MIM). The selection was motivated by the fact that the applicability of the MIM in peat soils finds a wide consensus. However, results from inverse modelling and a robust statistical evaluation of this peat provide evidence that the measured breakthrough of the conservative tracer, Cl− could be simulated well using the CDE. This is demonstrated by a very high Damköhler number (→infinity) suggesting instantaneous equilibration between the mobile and immobile phases; this underscores the redundancy of the MIM approach for this particular peat. Scanning electron microscope images of the peat show the typical multi-pore size distributions structure have been homogenised sufficiently by decomposition, such that physical non-equilibrium solute transport no longer governs the transport process. This is corroborated by the fact the soil hydraulic properties were adequately described using a unimodal van Genuchten-Mualem model between saturation and a pressure head of ~ −1000 cm of water. Hence, MIM is not the most suitable choice, and the long tailing of the Na+ breakthrough curve is caused by chemical non-equilibrium. Successful description was possible using the OSA model. To test our results for the unsaturated case, we conducted an unsaturated steady state evaporation experiment to drive Na+ and Cl− transport. Using the parameterised transport models from the saturated experiments, we could numerically simulate the unsaturated transport using Hydrus-1D. The simulation showed a good prediction of observed values, confirming the suitability of the parameters for use in a slightly unsaturated transport simulation. The findings improve the understanding of solute redistribution in the constructed fen.
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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".