the study of resuspension rates near the deep-sea floor. 230Th und 231Pa We know the production rate of 230 Th (Half-life 75400 y) and 231 Pa (half-life 32500y) from Uranium dissolved in the ocean. Their [...] halflife) is often more conservative. 227Ac 227 Ac is produced in marine sediments from the decay of 231 Pa. In contrast to 228 Ra, the strongest sources are in deep-sea sediments. We attempt to use this