PB-210 RADIOMETRIC DATING OF ESTUARINE SEDIMENTS FROM THE EASTERN COAST OF THAILAND

Abstract

Eighteen sediment cores were taken from the Bang Pakong and Chantaburi River estuaries. The excess Pb-210 concentration profiles obtained were used to calculate annual sedimentation rates and thus the age profiles of the cores. The dating model assumes a constant flux of Pb-210 from the decay of atmospheric Rn-222, followed by adsorption on suspended particulates which carry the Pb-210 to the estuarine sediments at a constant rate. The results of investigation showed higher values of sedimentation rate of Bang Pakong River mouth than those from Chantaburi River mouth. This is probably due to dramatic decrease of the mangrove forests in the area and as a result of diagenetic remobilization of Pb-210 in the deeper sections of the sedimentary column.