Radiometric dating (210Pb, 137Cs, 241Am) of recent ombrotrophic peat accumulation and evidence for changes in mass balance
- 1 June 1995
- journal article
- Published by SAGE Publications in The Holocene
- Vol. 5 (2), 141-148
- https://doi.org/10.1177/095968369500500202
Abstract
The paper summarizes and evaluates the results of 210Pb, 137Cs and 241Am analysis on 37 recent ombrotrophic peat profiles. From these and previously published data, it is concluded that radiometric measurements alone cannot be relied on to give an accurate chronology of peat accumulation. Where constrained by profiles of 241Am activity in the upper part and one or more pollen-dated horizons below this, 210Pb can provide good chronologies of peat accumulation provided the constraint does not displace the calculated 210Pb dates by more than c. 10%. Profiles of 137Cs activity, in most cases, fail to contribute significantly to dating recent peat. At somewhat degraded sites, the residual dry mass of peat representing the last c. 150 years is reduced. Further analysis of well-dated profiles suggests that this may reflect loss of catolelm peat newly exposed to aerobic decomposition processes after a fall in water table. Several mechanisms are proposed for the displacement and net loss of lead (including 210Pb) from peat profiles.Keywords
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