Tracking the fate of particle associated Fukushima Daiichi cesium in the ocean off Japan

Buesseler, K. O.*; German, C. R.*; Honda, Makio*; Otosaka, Shigeyoshi  ; Black, E. E.*; Kawakami, Hajime*; Manganini, S. M.*; Pike, S.*

A three year time-series of particle fluxes is presented from sediment traps deployed at 500 and 1000 m at a site 115 km southeast of Fukushima Daiichi Nuclear Power Plant (FDNPP). Results show a high fraction of lithogenic material, suggesting a lateral source of sediments. The accident-derived radiocesium were enhanced in flux peaks that, given variations in trap Cs/Pb ratios, are characteristic of material derived from shelf and slope sediments found from 120 to 500 m. The fluxes of radiocesium are an order of magnitude higher than a previously reported for the trap located 100 km due east of FDNPP. We attribute the large difference due to the position of our trap under the southeasterly currents that carry contaminated waters and resuspended sediments in to the Pacific. These higher sedimentary fluxes of radiocesium to the offshore are still small relative to the inventory of radiocesium currently buried nearshore.