摘要：Naturally occurring radionuclides
such as 230Th, 231Pa and 10Be are
removed from the ocean by scavenging
onto particles. Due to their
differing sensitivities to particle
composition and particle fl ux, 231Pa/
230Th and 10Be/230Th ratios measured
in marine sediments can be used
to trace past changes in biological
productivity of the ocean.
