Influence of chemical composition of precipitation on migration of radioactive caesium in natural soils

• Mobility of freshly added Cs-134 was higher in soil receiving acidic precipitation.
• Depth penetration of Cs-134 was higher in soil profiles with a thicker humus layer.
• Depth distribution of Chernobyl Cs-137 was not affected by precipitation type.

The aim of the present work was to study the impact of the chemical composition of precipitation on radiocaesium mobility in natural soil. This was done through column studies. Three types of precipitation regimes were studied, representing a natural range found in Norway: Acidic precipitation (southernmost part of the country); precipitation rich in marine cations (highly oceanic coastal areas); and low concentrations of sea salts (slightly continental inland areas). After 50 weeks and a total precipitation supply of ∼10 000 L m−2 per column, results indicate that acidic precipitation increased the mobility of 134Cs added during the experiment. However, depth distribution of already present Chernobyl fallout 137Cs was not significantly affected by the chemical composition of precipitation.