Vertical distribution of 210Pb and 226Ra and their activity ratio in marine sediment core of the East Malaysia coastal waters

Marine sediment cores were collected from two stations at East Malaysia coastal waters on June 2004. Activity concentrations of 210 Pb in sediment core were ranged from 11 Bqkg −1 to 84 Bqkg −1 dry wt. for SR 01 and 4 Bqkg −1 to 66 Bqkg −1 dry wt. for SB 03. Meanwhile, activity concentrations of 226 Ra in sediment core were varied significantly depending on the sampling location of SR 01 and SB 03 with ranged 17–26 Bqkg −1 dry wt. and 8–11 Bqkg −1 dry wt., respectively. The activity ratios of 210 Pb/ 226 Ra were no significantly different at all sampling stations with an average of 1.78. Refer to the entire results; the activities of 210 Pb and 226 Ra were higher at station SR 01 than station SB 03, but contrast with ratio of 210 Pb/ 226 Ra. The reasons of different 210 Pb and 226 Ra activity concentration and distribution of their ratios were strictly related to their half lives, environment origin, potential sources and behavior.