5:15 PM - 6:45 PM
[MAG34-P02] Evaluation of preferential flow on the spatial distribution of 137Cs in cedar forest soils in Fukushima Prefecture.
Keywords:Cs-137, The Fukushima Daiichi Nuclear Power Plant, preferential flow, dye tracer
There is variability in the inventory of 137Cs in forest soils. However, few studies have investigated the effects of preferential flow on this variability. This study aimed to clarify the effect of preferential flow on the spatial distribution and chemical form of 137Cs in soil by conducting an artificial rainfall experiment using a dye tracer. An artificial rainfall containing Rhodamine B was applied at a rainfall intensity of 90 mm/h for 180 mm in a plantation cedar forest in Minamisoma, Japan, and visually sampled dyed and unstained soils and cores by depth to investigate 137Cs and Rhodamine B concentration, saturated hydraulic conductivity, and chemical forms of 137Cs.
The results showed that for Rhodamine B concentrations, significant differences were observed between the unstained and dyed soils from 2.5 cm below the surface, confirming the occurrence of preferential flow. However, no significant difference was observed for 137Cs concentration, although the variance was large in dyed soils and higher values were obtained in dyed soils at all depths.
The variance of 137Cs concentration in dyed soil was large at 10-20 cm, and a positive correlation was observed between saturated hydraulic conductivity and 137Cs concentration. These results suggest that the pathway of preferential flow may not change significantly after 11 years since the accident, assuming that this variance in 137Cs concentration is the function of preferential flow after the accident. In the future, we plan to analyze the relationship between root and gravel content and Rhodamine B and 137Cs concentrations and report the results.
The results showed that for Rhodamine B concentrations, significant differences were observed between the unstained and dyed soils from 2.5 cm below the surface, confirming the occurrence of preferential flow. However, no significant difference was observed for 137Cs concentration, although the variance was large in dyed soils and higher values were obtained in dyed soils at all depths.
The variance of 137Cs concentration in dyed soil was large at 10-20 cm, and a positive correlation was observed between saturated hydraulic conductivity and 137Cs concentration. These results suggest that the pathway of preferential flow may not change significantly after 11 years since the accident, assuming that this variance in 137Cs concentration is the function of preferential flow after the accident. In the future, we plan to analyze the relationship between root and gravel content and Rhodamine B and 137Cs concentrations and report the results.