The Use of Ion Exchange Membranes for Isotope Analyses on Soil Water Sulfate: Laboratory Experiments
Bibliographic record
Abstract
To investigate the potential use of anion exchange membranes (plant root simulator [PRS] probes) for isotope investigations of the soil sulfur cycle, laboratory experiments were performed to examine the sulfate exchange characteristics and to determine the extent of sulfur and oxygen isotope fractionation during sulfate sorption and desorption on the probes in aqueous solutions and simulated soil solutions. The sulfate-exchange tests in aqueous solutions under varying experimental conditions indicated that the amount of sulfate exchanged onto PRS probes increased with increasing reaction time, initial sulfate concentration, and the number of probes used (= surface area), whereas the percentage of removal of available sulfate was constant irrespective of the initial sulfate concentration. The competition of nitrate and chloride in the solution lowered the amount of exchanged sulfate. The exchange experiments in a simulated soil under water-saturated and water-unsaturated conditions showed that a considerable proportion of the soil sulfate was exchanged by the PRS probes after about 10 d. There was no evidence for significant sulfur and oxygen isotope fractionation between soil sulfate and sulfate recovered from the PRS probes. Therefore, we recommend the use of PRS probes as an efficient and easy way to collect soil water sulfate for determination of its isotope composition.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".