Distribution of natural and man-made radionuclides during the reoccupation of GEOSECS stations 413 and 416 in the Arabian Sea: temporal changes

Measurement of natural and man-made 14C and 3H and man-made 90Sr, 239,240Pu and 241Am at two GEOSECS stations, GX 413 and 416 reoccupied two decades later are reported. Deeper penetration of nutrient and oxygen-poor intermediate waters along with man-made radionuclides, especially at GX 413 (near Bab el Mandab), are noticeable. The one-dimensional advection-diffusion model using pre-nuclear 14C data supports this observation as the vertical advection velocity at GX 413 is 11.8 m/y compared to the 3.6 m/y in the central north Arabian Sea (GX 416).