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Buesseler, K. O.*; German, C. R.*; Honda, Makio*; Otosaka, Shigeyoshi; Black, E. E.*; Kawakami, Hajime*; Manganini, S. M.*; Pike, S.*
Environmental Science & Technology, 49(16), p.9807 - 9816, 2015/08
Times Cited Count：22 Percentile：57.13(Engineering, Environmental)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.
Buesseler, K. O.*; German, C. R.*; Honda, Makio*; Otosaka, Shigeyoshi; Black, E. E.*; Kawakami, Hajime*; Manganini, S. M.*; Pike, S.*
no journal, ,
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. Results show a high fraction of lithogenic material in sinking particles, suggesting a lateral source of sediments. From Cs/Pb ratio in sinking particles, it was inferred that accident-derived radiocesium associate with slope and shelf sediments were resuspended and transported laterally to the offshore regions in winter and typhoon seasons. Continuous observation of such transport processes of particulate radiocesium near the seabed would be significant for better understanding of the fate of accident-derived radiocesium.
Sanial, V.*; Buesseler, K. O.*; Charette, M.*; Casacuberta, N.*; Castrillejo, M.*; Henderson, P.*; Juan Diaz, X.*; Kanda, Jota*; Masque, P.*; Nagao, Seiya*; et al.
no journal, ,
Radiocesium activities in the coastal ocean off Fukushima dropped by orders of magnitude within one year after the accident of Fukushima Dai-ichi Nuclear Power Plant (FDNPP), but have remained relatively constant over the past 5 years exceeding background values. We investigated distribution of radiocesium in surface seawater and submarine groundwater along the Fukushima coast in October 2015. Our highest radiocesium activities were not found in the ocean, but in groundwater samples underlying coastal beaches 35 km south from the FDNPP. This may be due to sorption of the extremely contaminated waters on to beach sands/clays early after the accident and subsequent desorption back in to the ocean. Submarine groundwater discharge, which is widely recognized to be an important vector for the transport of chemicals from land to ocean, is thus a non-negligible path for transport of Fukushima-derived radionuclides to the ocean.
Sr and Cs through 2016 from the Fukushima Dai-ichi nuclear accidentKenyon, J.*; Buesseler, K. O.*; Casacuberta, N.*; Castrillejo, M.*; Otosaka, Shigeyoshi; Drysdale, J.*; Pike, S.*; Juan Diaz, X.*
no journal, ,
This study attempts to reconcile the sources and relative inputs of Sr and Cs using the measured activities and their activity ratios of Cs/Sr off the coast of Japan. Pre-accident levels correlate with 1960's weapons testing fallout activity ratios of 1.6. Immediately following the accident, Cs/Sr ratios experienced a sharp increase before reaching an average of 39
1. Data from 2011 to 2016 off the coast of Japan show that radionuclide concentrations since the accident have been decreasing, but are not yet comparable to pre-accident levels in the areas immediately surrounding FDNPP. Areas farther away from FNDPP show ratios closer to pre-accident waters, giving insight to the transport and mixing of water off the coast of FDNPP. We observe that the release of radionuclides from FDNPP is ongoing, but at rates more than one thousand times lower than initial releases in 2011.
