Effects of local-scale decontamination in a secondary forest contaminated after the Fukushima nuclear power plant accident. (September 2017)

• Record Type: Journal Article
• Authors: Ayabe, Yoshiko; Hijii, Naoki; Takenaka, Chisato
• Is Part Of: Environmental pollution. Volume 228(2017)
• Page Start: 344
• Page End: 353
• Publication Date: 2017-09
• Subjects: Radiocesium -- Decontamination -- Nephila clavata -- Forest; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2017.05.041
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: We investigated whether local-scale decontamination (removal of the litter layer, superficial soil layer, and understory) in a secondary forest contaminated by the Fukushima nuclear power plant accident reduced 137 Cs contamination of the soil and litter. We also measured 137 Cs concentrations in plants and in the web-building spider Nephila clavata (Nephilidae: Arachnida), as an indicator species, to examine 137 Cs contamination in arthropods. One month after decontamination, the total 137 Cs contamination (soil + litter) was reduced by 20% (100 kBq·m −2 ) relative to that in an adjacent untreated (i.e., contaminated) area, which was however not statistically significant. Four months after decontamination, 137 Cs in the decontaminated area had increased to a level similar to those in the untreated area, and the air radiation dose in the decontaminated area was about 2.1 μSv·h −1, significantly higher than that in the untreated area (1.9 μSv·h −1 ). This may have been attributed to a torrential rain event. Although no statistically significant reduction was observed, most spiders had a lower 137 Cs contamination than that before the decontamination. This implied that the decontamination may have reduced 137 Cs transfer from soil via litter to N. clavata through the detrital food chains, but may not have reduced the amount of 137 Cs transfer through grazing food chains because the concentration of 137 Cs in living tree leaves was not reduced by the decontamination. In autumn, about 2 kBq·m −2 of 137 Cs was supplied from foliage to the ground by litterfall. The results suggested that removal of the litter and superficial soil layers in a contaminated forest may be ineffective. The present study suggests that the local-scale decontamination in a secondary forest had no effect on the reduction of 137 Cs contamination in the treated area. Graphical abstract: Highlights: A forest area contaminated after the Fukushima accident was decontaminated. Decontamination decreased soil + litter 137 Cs levels by 20%, but not after 4 months. Decontamination did not reduce plant 137 Cs concentrations or air radiation doses. The 137 Cs decreases in spiders (35%) was not statistically insignificant. A local-scale decontamination in a forest was not effective. Abstract : Local-scale decontamination in a 137 Cs contaminated forest was not effective.