Fig. 2: Excess protactinium-231/thorium-230 activity ratios in bulk surface sediments.
From: Radioisotope constraints of Arctic deep water export to the North Atlantic

Symbol shape indicates the data source; new data provided by this study are shown in circles. Orange and red symbols indicate 231Pa/230Th ratios above the production ratio (0.093), blue symbols indicate 231Pa/230Th ratios below the production ratio. The 1500 m isobath is shown in bold.