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We developed a simple and rapid method for detecting dissolved radio-Cs in litter and/or soil seepage water using nonwoven fabrics impregnated with copper-substituted Prussian blue (Cu-NF). In laboratory and field experiments, litter and/or soil seepage water including dissolved radio-Cs were passed through traditional lysimeter systems combined with seven sheets of the Cu-NF. We then examined the recovery ratios of dissolved 137 Cs in the Cu-NF. In the laboratory experiments with faster flow rates (11–2200 mm h −1 ), over 86% of the total dissolved 137 Cs in litter seepage water was detected in the Cu-NF and over 82% of the collected 137 Cs was present in the first three sheets. In the field experiments, 99% of the total dissolved 137 Cs litter seepage water was collected in the Cu-NF and more than 96% of the collected 137 Cs was present in the first three sheets. Furthermore, the recovery ratio of dissolved 137 Cs increased with increasing installation Cu-NF length, probably because the packed soil in the Cu-NF lysimeter become more stable over time. Finally, because only the Cu-NF is measured, it is not necessary to undertake traditional measurement preparations such as filtration to remove particulate radio-Cs materials and evaporative concentration for low concentration of radio-Cs. As a result, we can save time and effort in measurement preparation by using the Cu-NF lysimeter method. [ABSTRACT FROM AUTHOR]

The spatial variation of the radiocesium inventory in forest soil was studied c.a. 44 km northwest of the Fukushima Daiichi Nuclear Power Plant, Japan. This study focuses on the effects of canopy interception and downward transfer from the forest canopy to the forest floor via stemflow and throughfall. We established a study plot (400 m 2 ) in the canopy layer of a secondary mixed deciduous forest dominated by Japanese oak ( Quercus crispula ) and Japanese fir ( Abies firma ), in August and November 2014. Soil was sampled from 0 to 5 cm depth and 137 Cs was measured under the canopy using a 2-m grid and also at the tree trunk bases. We divided the study plot into the five different types of subplot according to the canopy projection areas and the tree species for the analysis. The geometric mean and coefficient of variation of the 137 Cs inventory were 202 kBq m −2 and 0.11 (0.52 in the arithmetic coefficient of variation), respectively. Within the forest, the variation in the 137 Cs inventory under trees was larger than in crown gap areas. The large spatial variation may be attributed to canopy interception of the initial deposition and downward transfer of radiocesium via stemflow and throughfall. [ABSTRACT FROM AUTHOR]