Resuspension of radiocesium from contaminated land surfaces in Fukushima: source contributions from soil, vegetation, and other sources

Overview of the observation and simulation studies regarding radiocesium resuspension from contaminated land surfaces in Fukushima is presented based on our previous papers, Kajino et al., ACP (2016), Kajino et al., ACP (2022), Watanabe et al., ACP (2022). The long-term atmospheric behaviors of radiocesium have been understood based on the long-term measurements of concentration and deposition of radiocesium in Fukushima city (Watanabe et al., 2022) and numerical simulations considering radiocesium resuspension from soil and vegetation (Kajino et al., 2022). However, there is still one unresolved issue remains: exceptionally high monthly cumulative deposition amounts in January in Fukushima city even though the monthly atmospheric concentrations are not very large. We therefore hypothesized that the giant aerosol resuspension due to snow removal work or passing vehicles that carried radiocesium deposited in the vicinity of the observation site into the deposition sampler, but not into the air sampler, since the gravitational velocity of such giant aerosols is too high to collect by the air sampler. This additional source is referred to as secondary resuspension. The numerical assessment and field observations of the secondary resuspension will also be presented at the conference.