Variation of 231Pa, 230Th and 231Paex/230Thex in surface sediments of the Sabah-Sarawak coastal waters

Protactinium and thorium activities were measured in eight surface sediment taken in 2004 to determine effectiveness scavenging of 231Pa at Sabah-Sarawak coastal waters. The result found that activity ratios of 231Paex/230Thex were ranged from 0.07 to 0.13 at all sampling stations. The high 231Paex/230Thex activity ratio than the production ratio of 0.093 in seawater at station SR 01, SR 02, SR 04, SB 02 and SB 05, revealed that 231Pa is effectively removed from the water column into the sediment in comparison with 230Th at those stations. Low percentage of 230Thex (90-95%) in comparison with 231Paex at all stations can be attributed to less efficiently scavenged of 230Th onto particles prior deposited at the marine sediment bed. (author)