Some Practical Considerations Regarding the Application of 210Pb and 137Cs Dating to Estuarine Sediments

Abstract

Estuarine environments potentially provide excellent geological archives and the two radioactive isotopes 210Pb and 137Cs can be used to date the most recent past, under ideal circumstances as far back as 120–150 years. However, some obvious (and some less obvious) requirements need to be fulfilled for the dating-methods to be applicable and estuaries are often challenging environments in this respect. This chapter discusses some of the most common problems and includes suggestions on prudent approaches which should be considered when evaluating the applicability of the two dating methods and when calculating chronologies. The problems include among others sediment mixing, grain size affinity, post depositional mixing and choice of dating model. The discussion is illustrated with examples from tidal flat, salt marsh and fjord sediments from temperate settings but the problems are universal and should be equally relevant for estuarine settings in other climatic zones.