Characterization of Arsenic Upon Liming and Formation of Residual NAPL in the Vadose Zone
Notice bibliographique
Résumé
Incorporation of lime amendments is an effective treatment to neutralize acidity, reduce soluble metals, and facilitate plant growth in mine wastes. In general, arsenic (As) solubility increases with increasing pH in As laden mine wastes. However, a number of laboratory and field studies have shown the decrease in As solubility with increase in pH. It has been hypothesized that reduction in soluble As was likely due to presence of amorphous oxides of iron, aluminum and manganese. Further, in experimental studies it has been seen that the total concentration of Fe+Al+Mn was approximately ten times higher in the mine wastes exhibiting decrease in soluble As. There was no correlation suggested with any single element. This study uses PHREEQC for geochemical modeling to investigate the factors and reaction pathways affecting changes in soluble-As concentrations upon liming acidic metalliferous mine wastes. The results indicate that a change in solubility of As upon liming is mainly affected by the presence of amorphous phases of aluminum. Iron and manganese oxides don't play a significant role. Managing contaminated sites (due to infiltration of NAPL) can be expensive, but multiphase models can be an effective tool to predict the subsurface behavior of contaminants and help reduce associated costs. One of the major deficiencies of such models is the prediction of the amount of residual non-aqueous phase liquids (NAPL). In order to accurately predict the behavior of residual NAPL, it is important to understand the formation of residual NAPL. The presence of residual NAPL in the vadose zone has been demonstrated by many researchers, but the conditions under which residual NAPL is formed are poorly understood. Traditionally permeability-saturation-pressure (k-s-p) relations have been used to demonstrate the formation of residual NAPL. Herein, we use electrical conductivity to investigate the process of formation of residual NAPL. Results from the experiments indicate formation of residual NAPL during drainage of NAPL from the system. Further, experimental studies ware undertaken to validate the model presented by Wipfler and van der Zee (2001) with experimental data set in which both oil and water pressure head are determined. Natural soil sample was used instead of Ottawa sand. Ottawa sand has a more uniform grain size than soils so this series of experiments tests the model in a more complex system. Another difference between previous studies and this experiment was the choice of NAPL. Oleic acid, which is a light NAPL was used herein instead of the dense NAPL used by Hofstee et al. (1997). Results from the experiments indicate that the model failed to predict the formation of the residual NAPL under the experimental conditions.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».