Sediment trap experiments in the water column off southwestern Taiwan:234Th fluxes

The activity of²³⁴Th (t_1/2=24.1 days) in dissolved, particulate and sediment trap samples was determined in the water column off southwestern Taiwan during 2–4 October, 1993. Vertical²³⁴Th fluxes measured by the free-floating sediment traps ranged from 363 to 2290 dpm m^–2 d^–1 in the upper 450 m. Th-234 fluxes predicted from the irreversible scavenging model concur with those measured by the sediment traps. Comparison of the residence times of particulate²³⁴Th and particulate organic carbon showed that their respective values differ by a factor of approximately 23, which suggests organic carbon is preferentially recycled relative to²³⁴Th in the euphotic zone.