Effects-Directed Analysis of Soluble Organics in Bitumen-Influenced Waters
Notice bibliographique
Résumé
Identification of the organic compounds of concern within bitumen-influenced waters is critical for effective monitoring and reclamation within Canada’s oil sands region. Effects-directed analysis (EDA) is a tool used to identify the toxic compound(s) in toxic mixtures through means of mixture fractionation, and biological and chemical analyses. Bioactive polar organic fractions (1°F3) from natural and industrial bitumen-influenced water sources (Aged oil sands process affected water (OSPW) – 1, OSPW Influenced Groundwater (GW) – 1, Natural GW – 1, and Natural GW – 2) subjected to a first tier EDA, were further fractionated in a second tier using reverse-phase high-performance liquid chromatography (HPLC). Four secondary fractions (2°F1, 2°F2, 2°F3, 2°F4), separated by polarity, were created along with a recombined treatment (2°FR) of the secondary fractions for sites OSPW influenced GW – 1, and Natural GW – 2. Toxicity was assessed using the Microtox® assay and Hyallela azteca due to sensitivities exhibited to the first tier EDA fraction. Due to the volume restraints of the second tier EDA analysis, a low-volume test method (50 mL and 10 organisms) was developed for the Hyalella azteca, which was a 4 – 8-fold volume reduction in comparison to standardized methods (200 – 400 mL and 15 – 20 organisms). Parallel tests of the low-volume method and standard method were completed to compare LC50s with two inorganic standards (KCl and CdCl2) and two organic solutions (naphthenic acid fraction component (NAFC) 2009 and NAFC 2011). Finally, chemical analysis of primary and secondary fractions was completed in positive and negative electrospray ionization (ESI) mode on a liquid chromatography quadrupole time of flight mass spectrometer (LC-QToF/MS). For the proposed Hyalella azteca low-volume test method, there was no evidence the LC50 values for KCl, NAFC 2009, and NAFC 2011 were different (p = 0.34, 0.73, and 0.48), however, there was some evidence the LC50 values for CdCl2 was different (p = 0.037). The percent difference between LC50 values were less than 1 – fold for KCl, NAFC 2009, and NAFC 2011, and was 2 – fold for CdCl2. Due to percent differences below 3 – fold, and 95% confidence intervals (CI) which overlap, the low-volume method is determined to be an acceptable replacement for standardized methods in testing situations with access to minimal volumes of solution. The Microtox® and reduced volume H. azteca assays were most sensitive to the polar organics of the primary fractions and secondary fraction recombined treatments. The toxicity response to the primary fraction was not observed in any of the individual secondary fractions, however, 2°FR from OSPW Influenced GW – 1 for the Microtox® assay (40% viability) elicited a comparable response to the 1°F3 (29% viability, p = 0.07). Additionally, there was no difference from Natural GW – 2 2°FR to 1°F3 (29 % viability) of the Microtox® assay (40% viability, p = 0.054) and the 1°F3 (0% survival) of the H. azteca assay (0% survival, p = 1.00). For the V. fischeri there were no obvious trends in the toxicity of the individual secondary fractions between sources but 2°F3 and 2°F4 had the greatest response within groundwater sites. Similarly, for the H. azteca there was no toxicological response in the individual secondary fractions, save for 2°F4 in the groundwaters: OSPW Influenced GW – 1 (78% survival), Natural GW – 1 (62% survival), and Natural GW – 2 (47% survival). The LC-QToF/MS total ion chromatograms (TICs) of the secondary fractions, were less complex in comparison to the primary fractions, but remain too chemically complex for compound identification. Additionally, the fraction profiles were distinguishable from the others with some degree of overlap between adjacent fractions. In conclusion, the lack of recoverable toxicity in the individual secondary fractions may indicate that there are interactive effects within the more complex mixtures of polar organics (e.g. 1°F3, 2°FR fractions) that lead to greater toxic potency than when the chemical components are separated into less complex mixtures (e.g. individual secondary fractions). Or, perhaps, the compounds driving the toxicity are split between adjacent fractions, below their response thresholds. Additionally, due to the complexity of the secondary fractions identified by the LC-QToF, another tier of EDA is required to analyze unknowns. It is therefore recommended that this second tier of EDA must be reinvestigated such that the secondary fractions are combined with their adjacent fraction.
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) | 0,001 | 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 | 0,000 | 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) | 0,001 | 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 ».