Application of Dendrochronological and Dendrochemical Methods for Dating Contamination Events of the Saint-François and Massawippi Riverbanks (Québec, Canada)
Notice bibliographique
Résumé
Abstract Soils contaminated with hydrocarbons and others contaminants (heavy metals, PCBs, PAHs) were recently discovered in the banks of the Saint-François and Massawippi rivers. The aim of this study is to attempt to date the contamination events using dendrochronological and dendrochemical methods. For this study, dendrochronology is used to indicate the age of trees, identify the morphological growth anomalies, and provide the geochemical profile timeframe, with dendrochemistry used specifically to identify metal element concentrations in the growth rings of the selected specimens. Sampling for the two types of analysis was done on the banks of the Saint-François River in Windsor and Richmond, where the level of hydrocarbon contamination in the soil profiles is among the highest. Core samples were taken from three red ash (Fraxinus pennsylvanica Marsh.) and dendrochemical analyses were done on the tree rings (191 samples). Dendrochemistry was successfully used to determine that there were heavy metals in the rings, and also to estimate the date of the contamination events by using tree-ring wood. Several contamination events were identified through the presence of lead and other metal trace elements (As, Cd, Cu, Ni, and Zn) in the xylem of the trees analyzed at the selected sites. This suggests that various contaminants were transported by the river on several occasions and deposited on floodplains during successive floods. The atmospheric fallout must also be considered as the other source of pollutants recorded in the trees. Keywords: contaminated soildendrochemistrydendrochronologyheavy metalhydrocarbonriverbank Acknowledgements The authors would like to thank all the individuals and organizations that contributed to this study, including the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Fond Institutionnel de Recherche (FIR-UQTR) for their financial support. We would like to acknowledge the Geological Commission of Canada (GCC-Québec) and INRS-ETE laboratory's support for the dendrochronology and dendrochemistry analyses. We would like to also acknowledge the reviewers for the constructive comments that helped to improve the manuscript. Lastly, we would like to extend our warm thanks to Luc Lavoie, François Péloquin, and Marc Laurencelle for their valuable assistance during field works and Francis Baril for his help for figures and maps. Notes Lead alkyls, in particular added to gasoline for their antiknock properties, were withdrawn in the USA in 1975, while the reduction of the lead content in gasoline began in Europe in the mid-1980s, and later, prohibition measures were adopted collectively by the European directives in the late 1990s (Directives Auto/Oil 98/69 and 98/70 of the European Parliament). In France, Germany, and other European countries, unleaded gasoline was first officially put on the market in 1990. In Canada, the lead content in gasoline was reduced in the 1980s (CitationBollhöfer and Rosman, 2001) and gasoline with lead was removed from the market for good in 1990 (CitationCEPA, 1990). *Tree sample used for replicate; **Values of soil profile samples. *Soils with hydrocarbon contaminant levels ranging from 300 to 700 mg/kg fall within Class B and have usage restrictions (CitationMDDEP, 2002). *The numbers in bold indicate the level of soil contamination in B Class (CitationMDDEP, 2002). The values obtained for PAHs and PCBs analysis are not included in the table. (i) Notes: Articles in regional newspaper (La Tribune) mentioning two cases of contamination on the Saint-François River in 1955 and 1963. "La rivière Saint-François, polluée sur une distance de 45 milles." La Tribune, Sherbrooke, 25 octobre 1955. "La rivière Saint-François est couverte de grandes mares d'huile—Origine inconnue." La Tribune, Sherbrooke, 17 mai 1963.
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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 ».