An investigation of the fate and transport of enteric bacteria in alluvial streams
Notice bibliographique
Résumé
Impairment of rural streams and receiving lakes as a result of microbial pollution has a significant impact on human health and quality of life. Contaminated drinking water supplies and the closure of recreational surface waters are two common consequences of microbial pollution. Many aspects of microbial survival and transport are poorly understood. For example, it is evident that stream sediments provide an environment suitable for the extended survival and possible growth of fecal microorganisms. Several watershed-scale studies have alluded to the presence of a reservoir of fecal microorganisms within stream sediments, but have not been able to quantitatively identify the relative contribution of this source to water quality degradation under varying hydrologic and environmental conditions. For areas of degraded water quality with many potential sources, understanding these processes is critical if appropriately directed watershed management plans are to be implemented. In this study, a combination of field experiments and mathematical modeling was used to elucidate the processes which control the fate and transport of enteric bacteria in alluvial streams. The overall objective of the research was to further the development of microbial water quality models. A tracer bacterium, 'Escherichia coli' NAR, was used to investigate the survival, resuspension, advective-dispersive movement, and settling of sediment-associated bacteria in several natural alluvial streams. This study has illustrated that enteric bacteria can survive in bed sediments for up to 6 weeks. Inactivation of the tracer-bacteria within bed sediments of the majority of the streams studied resembled typical first order decay. However, in the nutrient-rich bed sediments in Carroll Creek, ON, Canada, where water temperatures were typically lower than 16°C, the inactivation of the tracer-bacteria did not follow a first order decay. The number of tracer-bacteria within the stream bed did not decrease for the first five days of the experiment. Results from a detailed monitoring study conducted in Swan Creek, ON, Canada has provided information pertaining to the resuspension of sediment-associated bacteria due to natural hydrologic influences. Critical conditions for resuspension, as well as resuspension rates, of sediment-associated bacteria were determined for several storm events. Field experiments and mathematical modeling were used to determine dispersion coefficients, deposition rates, and partitioning coefficients for sediment-associated bacteria in two natural streams. The results provided evidence that bacterial adsorption can be modeled as an irreversible process in freshwater environments. Calibrated net settling velocities of sediment-associated bacteria were found to be comparable to literature values for fine sediments. The information presented in this study will further the development of representative microbial water quality models. Recommendations for improving current microbial water quality models, and for future research have also been outlined.
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 | 0,000 |
| 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 | 0,001 | 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 ».