Temporal variation of post-accident atmospheric 137 Cs in an evacuated area of Fukushima Prefecture: Size-dependent behaviors of 137 Cs-bearing particles
The concentrations of Cs in the air, which were divided into coarse (>1.1 μm ϕ) and fine (<1.1 μm ϕ) fractions of particulate matter (PM), were measured from October 2012 to December 2014 in an area evacuated after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Total atmospheric...
Saved in:
Published in | Journal of environmental radioactivity Vol. 165; pp. 131 - 139 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
England
01.12.2016
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | The concentrations of
Cs in the air, which were divided into coarse (>1.1 μm ϕ) and fine (<1.1 μm ϕ) fractions of particulate matter (PM), were measured from October 2012 to December 2014 in an area evacuated after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Total atmospheric
Cs concentrations showed a clear seasonal variation, with high concentrations during summer and autumn related to the dominant easterly wind blowing from the highly radioactivity contaminated area. This seasonal peak was dominated by
Cs in the coarse PM fraction. The
Cs specific activity (massic
Cs concentration) in the coarse PM was also found to increase significantly in summer, whereas that in the fine PM showed no variability during the year. These results show that coarse and fine
Cs-bearing PM have different origins and behaviors in the resuspension process. The seasonal variation in atmospheric
Cs concentration was well correlated with the mean
Cs surface contamination (deposition density) around the observation site weighted by the frequency of wind direction, indicating that the atmospheric
Cs concentration in the observation site was explained by the distribution of the
Cs surface contamination and the frequency of different wind directions. We introduced a resuspension factor corrected for wind direction, consisting of the ratio of the atmospheric
Cs concentration to the weighted mean
Cs surface contamination, which evaluated the intensity of resuspension better than the conventional resuspension factor. This ratio ranged from 5.7 × 10
to 8.6 × 10
m
and gradually decreased during the study period. |
---|---|
ISSN: | 0265-931X 1879-1700 |
DOI: | 10.1016/j.jenvrad.2016.09.014 |