The Interaction between Hydrography and the Scavenging of 230Th and 231Pa Around the Polar Front, Antarctica

The removal rate of particle-reactive radionuclides from the water column depends on particle concentration and on particle flux. The high export productivity that is associated with the southern Polar Front is therefore characterized by high scavenging rates. The distribution of natural radionuclides from the Uranium decay series in the water column is however not only determined by scavenging patterns, but also by transport of water masses. A major parameter controlling this distribution is the ratio between the scavenging residence time of the particular isotope and the residence time of the water mass in a particular rain rate regime. It will be shown how the distribution of natural radionuclides with appropriate scavenging residence times can be used to obtain information on both time scales.