An investigation of chromium and strontium sources in MacAskill Brook Watershed and MacAskill Reservoir, Nova Scotia, Canada: implications for watershed and reservoir management
Notice bibliographique
Résumé
This thesis details an integrated paleolimnological—groundwater—soils study in northeastern Cape Breton focussed on identifying the sources of chromium (Cr) and strontium (Sr) within the watershed surrounding a reservoir. The sources of these metals and their pathway into the water in the reservoir is of interest because both metals present a management challenge. The sludge produced as a waste product of water treatment contains elevated Cr, which is an environmental concern and a significant treatment expense. The introduction of freshwater mussels is being considered as a treatment for elevated water colour and because shellfish are known to bioaccumulate Sr. An understanding of the source(s) of Sr is required to determine the environmental implications of this strategy.MacAskill Reservoir is a constructed 329 ha reservoir that drains a 3763 ha watershed and is a potable water source for about 24 000 people. The reservoir watershed is underlain by Carboniferous strata and has been the focus of extensive underground coal mining and surface processing; both coal and marine sediments are considered significant geogenic Sr and potential Cr sources. The overlying glacial till and related soils were generated in part from nearby marine-derived sedimentary strata (sources of Cr and Sr) and nearby ultramafic deposits (source of Cr). Anthropogenic activities in the region (junkyards, coal-powered generation stations, agricultural fields and fertilizers) must also be considered as possible sources of Cr and Sr. To provide as comprehensive an assessment as possible, surface water, groundwater, soils, and paleolimnological samples from a nearby lake and the reservoir were assessed.This study determined that Cr is most prevalent in watershed soils and that Sr appears in the highest concentrations in groundwater. Glacial till underlying the watershed appears to be the primary source of both metals, though local bedrock may also contribute to elevated Sr in water samples. Paleolimnological data indicates that Sr and Cr were probably not transported atmospherically to the site in detectable concentrations. Due to the acidic water and soil in the area, the Cr is reduced in the soil as the stable Cr(III) rather than mobilized in the water column as the more toxic Cr(VI). Cr in the soil is suspected to be elevated because of the glacial till transported from the Boisdale Hills, where mine tailings indicate concentrations greater than 440 mg/kg. Elevated Sr in groundwater is associated with chemical sedimentary rocks in the watershed, particularly the coal-bearing measures that have been mined extensively.The risk of Cr and Sr release into surface and groundwater systems and subsequently into the reservoir can be reduced by limiting landscape disturbances, particularly the wetlands located on the northwestern side of the watershed. Legacy coal workings also have significant potential to release Cr and Sr into water systems and require further assessment and monitoring to better understand the risk. As well, long-term monitoring of the watercourse and reservoir limnology may help determine how seasonality impacts Cr and Sr release into the reservoir.
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 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 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 ».