Trace elements in peat bog surface waters as indicators of the dissolution of atmospheric dusts from open-pit bitumen mines
Notice bibliographique
Résumé
Open-pit mining for bitumen extraction generates considerable volumes of dust in northern Alberta. This area contains abundant peatlands, some of which are ombrotrophic bogs that are exclusively fed by atmospheric inputs. The most reactive mineral phases of dust deposited on these bogs can potentially dissolve in their surface waters because of the low pH and abundance of organic acids. Thus, peat bog surface waters could be used as unique monitors, to determine the chemical reactivity and dissolution characteristics of atmospheric dusts in industrial areas. The main goal of this study is to determine whether the elevated rates of dust deposition to peat bogs near bitumen mines have led to greater concentrations of trace elements (TEs) in the surface waters. To achieve this goal, it is essential to ensure that the TEs being measured in surface waters represent dust dissolution only and are not influenced by other element sources such as groundwaters or surface runoff. Peat bog surface waters were collected in the autumn of 2019 from four peatlands near industry and a control site located more than 260 km upwind. Concentrations of TEs were determined in the dissolved fraction (i.e. filtered through a 0.45 μm membrane) using an ICP-MS. Surface waters near industry have elevated concentrations of Li, Fe, Mn, Ni, Y, selected REE (Tm, Dy, Yb, Sm) and Pb at 3 out of 4 sites, relative to the control location (UTK). Most of the elements are enriched 2x when compared to control site (UTK), but only Li, Mn, and Rb show enrichments >1Ox. At JPH4, the site closest to industry (12 km from the mid-point between the two central bitumen upgraders), a vegetation survey indicates that this peatland includes both ombrotrophic and minerotrophic zones, and this was confirmed by the pH and concentrations of major ions in the surface waters. At McK, the site next closest to industry (25 km), electrical conductivity as well as concentrations of chloride, Na, and K, all increase with distance toward the highway which is evidence of road salt runoff. Thus, at these two sites nearest industry, the TE concentrations in surface waters are supplied not only from airborne dusts, but contributions from groundwaters and road salt must also be considered. In contrast, the surface waters from the McM (49 km) and ANZ (69 km) sites are ombrotrophic, and elevated concentration of TEs in these samples can be attributed exclusively to dust dissolution. The elevated concentrations of lithophile TEs in the dissolved fraction includes those which are mobile in surficial environments (e.g. Li and Sr), but also those which are immobile (e.g. Y and the lanthanides). Elevated concentrations of the former are not surprising, but elevated concentrations of the latter are puzzling, given that they tend to be hosted within stable mineral phases that are resistant to chemical weathering. Size-resolved TE analyses of the dissolved fraction using AF4-ICP-MS will be used to distinguish between colloidal forms and ionic species, to differentiate inputs of nano-dusts from mineral dissolution in bog waters.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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 | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».