Susumu Miyazu

Development of a copper-substituted, Prussian blue-impregnated, nonwoven cartridge filter to rapidly measure radiocesium concentration in seawater

ABSTRACT This paper presents a cartridge filter incorporating a nonwoven fabric impregnated with Prussian blue copper analog (Cu-CF) to effectively concentrate and quantify radiocesium dissolved in seawater. The recovery ratio of the Cu-CF was >95% in laboratory experiments at a flow rate of 0.5 L min−1 through the filter and >93% in field experiments. Test measurements of 137Cs concentrations in seawater using Cu-CF agreed with the results obtained by using a conventional coprecipitation method that employed ammonium phosphomolybdate (within the counting error of the detector). The proposed method can shorten the preconcentration and pretreatment times for radiocesium, to just 40 min in 20 L of seawater, which is much faster than the ∼1 week required by traditional ammonium phosphomolybdate methods.

Measurement and estimation of radiocesium discharge rate from paddy field during land preparation and mid-summer drainage

In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation.