Models of the equilibrium distribution of organic chemicals between water and solid phases of environmental media
Bibliographic record
Abstract
Water–solid phase equilibrium distributions are foundational to multimedia environmental fate models of anthropogenic organic chemicals. This contextual review of equilibrium models of ionizing organics in aqueous–solids systems highlights the broad range of modeling assumptions and paradigms that have been employed. The complexity of soils and sediment, especially the organic phase, is provided as background along with a description of equilibrium models for nonpolar, nonionizing organics. The ways in which these single-species models have been modified and adapted for application to ionizing organics is detailed. The individual species proposed as contributing to observed distributions include the neutral parent, ions, and ion pairs. The debate over the role of the organic phase in soil and sediment solids is presented. Both absorption and surface adsorption models are described. Organic carbon (OC)-dependent models range from the simple Karickhoff equation to complex molecular connectivity indices models and polyparameter linear free energy relationship (pp-LFER) models. Adsorption models are derived from inorganic interaction chemistry. They include the early Langmuir model and Freundlich equation and continue to the modern Model VI and the NICA-Donnan model. Adsorption models focus on the mineral phase, but the role of the organic phase is not entirely dismissed. Dual mode models seek to combine absorption to OC with adsorption interactions. Conclusions drawn from studies of acid behavior do not predict the sorption of bases; bases are described separately. No single explanation and accompanying model of the distribution behavior of ionizing organics has emerged as the clear choice for regulatory use. The complexity of chemical–environment interactions is such that models are either challenging to parameterize and understand or they fail to capture key aspect(s) of the system critical to understanding of one or more classes of chemical or environmental medium. Future research directions are suggested including the possible benefit of removing sorbate–sorbent or chemical–environment distinctions.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.004 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".