Distributions of 210Po and 210Pb radioactivity in the intermediate layer of the northwestern North Pacific

The distributions of ²¹⁰Po and ²¹⁰Pb in the intermediate layer (400–2000 m) of the northwestern North Pacific were determined to elucidate the export flux of particulate matter. ²¹⁰Po generally showed depletion relative to ²¹⁰Pb in the intermediate layer, suggesting that ²¹⁰Po was scavenged by particles. Because the removal rate constants of ²¹⁰Po in the western region were higher than those in the eastern region and this trend coincided with that of the particle fluxes in the surface layer, the export production in the surface layer was assumed to influence the particle flux in the intermediate layer of the northwestern North Pacific.