© 2015 Elsevier B.V. The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100-150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within somepeat profiles. In this study, we introduce the Initial Penetration-Constant Rate of Supply (IPCRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations fromthe typical exponential decay profile not explained by variations in peat accumulation rates. Unlike themost commonly used 210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the sameareas. Confidence in the IP-CRS chronology is also provided by the good agreementwith independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.
|Journal||Science of the Total Environment|
|Publication status||Published - 15 Jan 2016|
- 137 Cs
- 210 Pb
- 241 Am