In order to assess the effect of marine and terrestrial environmental change in the last decades on the sedimentation environment
in Ariake Bay, we collected three sediment cores. The concentrations of natural and anthropogenic radionuclides, major elements,
and rare-earth elements were measured using gamma-spectrometry and neutron activation analysis. Vertical distributions of
both radionuclides and sedimentation rates, determined using Cs-137 and Pb-210ex dating methods, varied significantly among the sites.