Stylianos Stoulos

¹³⁷Cs and ⁴⁰K concentrations in soil and air were measured since 1986. ¹³⁷Cs wind-resuspension factor was 7.4 ± 1.3 × 10^–6 m⁻¹ after Chernobyl, while one decade later, it reduced to 1.5 ± 0.3 × 10^–9 m⁻¹, but for ⁴⁰K was constant 7.4 ± 1.3 × 10^–9 m⁻¹ The air ¹³⁷Cs-to-⁴⁰K ratio was 12:7 after the accident, dropping to 0.04 during 1995. The Fukushima accident gave 1.0, which is like a radiological event in Spain when it was 0.6. The Chernobyl wildfires recorded 0.18, while contaminated wood combustion for heating showed 0.15. The results indicate that forest ecosystems remain a source of unwanted radioactivity in the environment.

Indoor radon source potential from unground soil was monitored using prototype devices approaching a dwelling with a cellar basement at 1 depth from the soil-atmosphere interface. Therefore, the radon concentrations in soil gas were monitored at 1 m depth. Integrated radon measurements were performed, and the results correlated with meteorological parameters. The influence of the difference in outdoor and device-soil temperature was considered, and the infiltration rate was calculated. The effect of the soil temperature gradient on the soil radon entry rate was evaluated. The indoor radon entry rate due to the soil gas was 7.0 ± 2.7 Bq m⁻³ h⁻¹. The radon entry rate was 5.0 ± 0.8 Bq m⁻³ h⁻¹ due to diffusion. In contrast, the advection-drive flow of soil gas is ranged up to ± 4.0 Bq m⁻³ h⁻¹. So, the infiltration rate of the model dwelling was 0.7 (± 0.5) × 10⁻¹ h⁻¹ if only the stack effect occurred. The radon levels in tap water were measured, and the radon entry rate was estimated at 1.3 ± 0.7 Bq m⁻³ h⁻¹. If the ventilation rate is low or seismic faulting appears, the soil radon entry is increased by one order of magnitude. The soil radon appeared like the building materials, having 1/3 of the total indoor radon entry, while outdoor air was slightly lower (28%), with tap water at 5%. The resident’s mortality risk occurred at < 2.5% for typical dwellings in temperate climate areas founded on sand-gravel underground. The risk rises to 34% with an extremely low ventilation rate between indoors and outdoors or high radon entry from the soil due to seismic faulting.

Time series analysis was applied to the continuous radon level, temperature, pressure, and rainfall to find clear earthquake signals. Radon signals appeared a few days after heavy rains, and radon signals associated with events M = 3.8–4.2 were detected 12 up to 36 days before. The events are complete data recorded from 1983 to 1986, giving discussion and conclusion on M with prediction time and radon anomaly detected in the Stivos faulting near Thessaloniki, N. Greece.

Radon entry rates indoors were monitored using prototype devices approaching a dwelling with a cellar basement at 1 m depth. The radon concentrations in soil gas were also measured at 1 m depth. Integrated measurements were performed, and the results correlated with meteorological parameters. The influence of the difference in outdoor and device-soil temperature was discussed, and the infiltration rate was calculated. The effect of the soil temperature gradient on the soil radon entry rate was analyzed. The indoor radon entry rate due to the soil gas was 7.0 ± 2.7 Bq m^− 3 h^− 1. The radon entry rate.was 5.0 ± 0.8 Bq m^− 3 h^− 1 due to diffusion. The advection-drive flow of soil gas is ranged up to ± 4.0 Bq m^− 3 h^− 1. The infiltration rate of the model dwelling was 0.7 (± 0.5) x10^− 1 h^− 1 if only the stack effect occurred. The soil radon entry is increased by one order of magnitude when the ventilation is low or seismic faulting appears. The radon levels in tap water were measured, and the radon entry rate was estimated at 1.3 ± 0.7 Bq m^− 3 h^− 1. The soil radon appeared like the building materials rate, having 1/3 of the total, while outdoor air was slightly lower (28%), with tap water at 5%. The resident's mortality risk occurred at < 2.5% for typical dwellings in temperate climate areas founded on sand-gravel underground. The risk rises to 34% with an extremely low ventilation rate and high radon entry from the soil and building materials.