A framework for 210Pb model selection and its application to 37 cores from Eastern Canada to identify the dynamics and drivers of lake sedimentation rates. Issue 10 (16th June 2022)

• Record Type: Journal Article
• Authors: Baud, Alexandre; Aulard, Candice; Ghanbari, Hamid; Fradette, Maxime; Antoniades, Dermot; del Giorgio, Paul; Huot, Yannick; Francus, Pierre; Smol, John; Gregory‐Eaves, Irene
• Is Part Of: Earth surface processes and landforms. Volume 47:Issue 10(2022)
• Page Start: 2518
• Page End: 2530
• Publication Date: 2022-06-16
• Subjects: 210Pb -- CFCS -- CIC -- CRS -- dating models -- land use -- paleolimnology -- radiochronology -- sedimentation rates; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.5391
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: 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 ( 210 Pb) 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 × 10 6 km 2 ). 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. Abstract : We developed a methodological framework for assessing the fit of three of the main sediment dating models to measured 210 Pb radioisotopic activities from cores from Eastern Canada. Using this method, we were able to track recent accelerations in lake sediment mass accumulation rates recorded in all four ecozones that we investigated. This acceleration was correlated with the intensity of anthropogenic activities within lake watersheds, such as human population growth and agricultural land use.