High resolution profile of radiocaesium deposition in Loch Lomond sediments - a failure of ¹³⁷Cs dating

Abstract

A sediment core from the southern basin of freshwater Loch Lomond, Scotland, was thinly sectioned at 3mm intervals and analysed for radiocaesium, present as a result of fallout from the atmospheric nuclear weapons' testing programme of the 1950s and 1960s and from the Chernobyl reactor accident of April 1986. The high-resolution sampling enabled much improved resolution of peaks from weapons testing fallout and Chernobyl and led to the estimation of a sedimentation rate (30.9mgcm^-2y^-1) for which the uncertainty was a factor of five times less than that of a previous study based on a 1cm sampling frequency. Further potential advantages of high-resolution sampling in distinguishing possible influences upon the vertical distribution of radiocaesium in sediments are discussed.