A framework for 210 Pb model selection and its application to 37 cores from Eastern Canada to identify the dynamics and drivers of lake sedimentation rates.

Baud, Alexandre; Aulard, Candice; Ghanbari, Hamid; Fradette, Maxime; Antoniades, Dermot; del Giorgio, Paul A.; Huot, Yannick; Francus, Pierre ORCID: https://orcid.org/0000-0001-5465-1966; Smol, John P. et Gregory-Eaves, Irene (2022). A framework for 210 Pb model selection and its application to 37 cores from Eastern Canada to identify the dynamics and drivers of lake sedimentation rates. Earth Surface Processes and Landforms , vol. 47 , nº 10. pp. 2518-2530. DOI: 10.1002/esp.5391.

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Résumé

Lake sedimentation rate represents a synthetic metric of ecosystem functioning. Many localized studies have reported a significant association between land use/land cover changes and lake sediment mass accumulation rates, with a few global syntheses echoing these findings at larger scales. In the literature, studies evaluating lead-210 (210Pb) for establishing sediment chronologies will report at least one of three dating models, but the constant rate of supply (CRS) model is the most widely used. However, it is often unclear how or why this model is selected, despite its influence on the interpretation of many subsequent analyses about ecosystem dynamics and functioning. It would thus be advantageous to design an objective and semi-automated way of choosing among dating models. We measured radioisotopic activities in 37 sediment cores across four ecozones of Eastern Canada and developed an approach to assess model fit for the three commonly applied dating models. The derived chronologies were then used to evaluate the spatial and temporal variation in sedimentation rates across four ecozones in Canada (covering a surface area of 2.2 × 106 km2). We observed a recent increase in lake sedimentation rates across most lakes, as has been observed globally, albeit with significant differences in the magnitude of sedimentation rates across ecozones. Across all lakes, we found that regional human population counts and mean annual air temperatures were significant temporal predictors of variation in mass accumulation rates. Overall, this analytical framework offers an objective approach for assessing fit and selecting among sediment age models, which contributes to a more robust quantification of sedimentation rates. With this first application, we provide a quantitative assessment of how lake sedimentation rates have varied across a northern lake-rich region and have responded to environmental change.

Type de document:	Article
Mots-clés libres:	210Pb; CFCS; CIC; CRS; dating models; land use; paleolimnology; radiochronology; sedimentation rates
Centre:	Centre Eau Terre Environnement
Date de dépôt:	24 janv. 2023 18:41
Dernière modification:	06 juin 2023 19:18
URI:	https://espace.inrs.ca/id/eprint/13069

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