@misc{oai:repo.qst.go.jp:00072602,
 author = {乙坂, 重嘉 and 福田, 美保 and 青野, 辰雄 and 福田 美保 and 青野 辰雄},
 month = {Aug},
 note = {Within a year after the accident of Fukushima Daiichi Nuclear Power Plant (FDNPP) that occurred on March 11, 2011, 0.2±0.05 PBq of 137Cs was deposited onto the seabed.  Theconcentration of 137Cs in seabed sediment has also shown a decreasing trend, but the rate is slow relative to that in the seawater. Consequently, it is pointed out that the seafloor off Fukushima can continuously supply 137Cs to the bottom waters and benthic foodweb.  In this study, behavior of dissolved radiocesium near the seafloor is discussed from the distributions of 137Cs in overlying water (seawater collected from ~30 cm above the seabed) at 14 stations and in pore water at three stations off Fukushima. 
The 137Cs concentrations in overlying water, collected during 2015 and 2016, ranged between 5 and 283 mBq/L, and increased in stations where higher 137Cs concentrations were observed. Concentrations in overlying water were 2~3 times higher than those in seawater collected from intermediate (3~5 m above the bottom) layers. Finally concentrations in pore water were 10~30 times higher than those in overlying water. 
Regardless of the pore size of the filter (0.45 μm, 0.2 μm and 1kDa) used for filtration, 137Cs concentrations in overlying water were similar at each station. We can therefore consider that radiocesium is “dissolved” in the overlying water and has been diffused from the seabed through the porewater.  Nevertheless, the effect of 137Cs supply to the benthic environment is insignificant because estimated amount of 137Cs transferred to benthic organisms does not lead to 137Cs activities exceeding the regulation limits at most stations. 
Apparent distribution coefficients (Kd) of 137Cs between sediment and porewater were 140~350 L/kg, and fell within a certain range regardless of the concentration or penetration depth of radiocesium in the sediment. This indicates that equilibrium of the accident-derived 137Cs has been reached in the porewater-sediment system., Goldschmidt2017},
 title = {Behavior of radiocesium at sediment-water interface off Fukushima},
 year = {2017}
}