Feasibility of I groundwater dating calibrated by both Kr and He for the assessment of deep geological repositories in Japan.

Iodine-129, which is a promising tracer for dating old groundwater, has been used as a tracer for deep upwelling groundwater. The nuclide is expected to be one of the key factors for site selection for high-level radioactive waste disposal, which is a global societal issue. The pre-anthropogenic I/I ratio for marine iodine is (1.

Tritium concentration in the modern commercial DO reagents.

We investigated the tritium concentration in commercial modern DO reagents frequently used in nuclear magnetic resonance analysis for analytical chemistry and in environmental tracer testing. The concentration of tritium in 11 DO and 1 HO reagents ranged from 61 Bq/L (5 × 10 TU) to 2.5 × 10 Bq/L (2 × 10 TU) in order of magnitude.

Record of H and Cl from the Fukushima nuclear accident recovered from soil water in the unsaturated zone at Koriyama.

The opportunity to measure the concentrations of H and Cl released by the Fukushima nuclear accident in 2011 directly in rain was lost in the early stage of the accident. We have, however, been able to reconstruct the deposition record of atmospheric H and Cl following the accident using a bore hole that was drilled in 2014 at Koriyama at a distance of 60 km from the accident. The contributions of H and Cl from the accident are 1.

Origin and hydrodynamics of xylem sap in tree stems, and relationship to root uptake of soil water.

Although 10 years have passed since Japan's Fukushima nuclear accident, the future radiation risk from Cs contamination of wood via root uptake is a serious concern. We estimated the depth at which the roots of evergreen coniferous sugi (Cryptomeria japonica) and broadleaf deciduous konara (Quercus serrata) trees actively take up soil water by using positive δD values from the artificial DO tracer and seasonal changes in the δO values of soil water as a natural environmental tracer. We compared the tracer concentration changes in xylem sap with those in the soil water and ascertained that both tree species primarily took up water from a depth of 20 cm, though with mixing of water from other depths.

Atmospheric direct uptake and long-term fate of radiocesium in trees after the Fukushima nuclear accident.

Large areas of forests were radioactively contaminated by the Fukushima nuclear accident of 2011, and forest decontamination is now an important problem in Japan. However, whether trees absorb radioactive fallout from soil via the roots or directly from the atmosphere through the bark and leaves is unclear. We measured the uptake of radiocesium by trees in forests heavily contaminated by the Fukushima nuclear accident.

Aging effect of 137Cs obtained from 137Cs in the Kanto loam layer from the Fukushima nuclear power plant accident and in the Nishiyama loam layer from the Nagasaki A-bomb explosion.

We measured (134)Cs and (137)Cs in the surface soil of the Kanto loam in the eastern Tokyo metropolitan area and the Nishiyama loam in Nagasaki, Japan. The observed (137)Cs deposition in the Kanto loam from the Fukushima nuclear power plant (NPP) accident ranged from 4.0 to 77 kBq m(-2), which corresponds to 0.

Prediction of groundwater contamination with 137Cs and 131I from the Fukushima nuclear accident in the Kanto district.

We measured the concentrations of (131)I, (134)Cs, and (137)Cs released from the Fukushima nuclear accident in soil and rainwater samples collected March 30-31, 2011, in Ibaraki Prefecture, Kanto district, bordering Fukushima Prefecture to the south. Column experiments revealed that all (131)I in rainwater samples was adsorbed onto an anion-exchange resin. However, 30% of (131)I was not retained by the resin after it passed through a soil layer, suggesting that a portion of (131)I became bound to organic matter from the soil.