The distribution of 231Pa, 228Th, 230Th, 232Th and 234Th in the Arabian Sea was studied on water samples, sediment trap matter and surface sediments. Strong variations of the particle flux forced by the monsoon are influencing the vertical and lateral radionuclide fluxes. The strong boundary scavenging effect was studied on the distributions of 231Pa and 230Th. In the central Arabian Sea 40...50 of 231Pa produced in the water column are exported to the coasts. Near the shelf of the Arabian Peninsula up to 150 231Pa more than produced in the overlying water column are deposited in sediments. With radionuclid budget calculations the trapping efficiencies of sediment traps deployed in the Arabian Sea was estimated. For deep traps (3000 m) efficiencies of 90...118 and for a shallow trap (500 m) 50 were calculated. These results corroborate those of other investigations, finding a strong undertrapping for shallow traps. A new method for radionuclid determination using HR-ICP-MS was developed and applied. With this method detection limits and precisions comparable with TIMS were achieved, while the requirements of measurement time and sample preparation were reduced
