Evaluation of Cs ageing by dynamics of Cs/Cs ratio in Andosol paddy fields with/without potassium fertilizer application.

The mobility of Cs in soil decreases with time owing to fixation by micaceous minerals. Such ageing is a critical parameter for estimating and predicting annual change in Cs contamination risk of agricultural products. The decrease in the exchangeable fraction of Cs has traditionally been used as an index of the Cs ageing.

Radiostrontium monitoring of bivalves from the Pacific coast of eastern Japan.

In early April 2011, radiostrontium was accidentally released from the Fukushima Daiichi Nuclear Power Plant to the Pacific coast of eastern Japan. We developed a simple procedure to analyze radiostrontium levels in marine mussels (Septifer virgatus) and seawater using crown ether (Sr Resin; Eichrom). Then, we used our method to describe the spatial and temporal distribution of radiostrontium in mussels and seawater on the Pacific coast of eastern Japan from 2011 to 2013 and for 2015.

Influence of water management and fertilizer application on (137)Cs and (133)Cs uptake in paddy rice fields.

Cesium-137 derived from the Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated large areas of agricultural land in Eastern Japan. Previous studies before the accident have indicated that flooding enhances radiocesium uptake in rice fields. We investigated the influence of water management in combination with fertilizers on (137)Cs concentrations in rice plants at two fields in southern Ibaraki Prefecture.

Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice.

A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ((137)Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice.

Arsenic behavior in paddy fields during the cycle of flooded and non-flooded periods.

The behavior of As in paddy fields is of great interest considering high As contents of groundwater in several Asian countries where rice is the main staple. We determined the concentrations of Fe, Mn, and As in soil, soil water, and groundwater samples collected at different depths down to 2 m in an experimental paddy field in Japan during the cycle of flooded and non-flooded periods. In addition, we measured the oxidation states of Fe, Mn, and As in situ in soil samples using X-ray absorption near-edge structure (XANES) and conducted sequential extraction of the soil samples.