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Radiocaesium fallout behaviour in volcanic soils in Iceland
M A Sigurgeirsson1, O Arnalds, S E Palsson
1Icelandic Radiation Protection Institute, Raudararstigur 10, IS-150 Reykjavik, Iceland. ms@gr.is
Journal of Environmental Radioactivity
|December 2, 2004
Summary
Radiocaesium (137Cs) fallout is strongly retained in Iceland's Andosols, primarily in the top 5 cm of soil. Vertical migration is minimal, though erosion and wind can redistribute radiocaesium.
Area of Science:
- Environmental Science
- Soil Science
- Radiochemistry
Background:
- Radiocaesium (137Cs) is a significant radionuclide pollutant from nuclear fallout.
- Understanding 137Cs distribution in soils is crucial for environmental risk assessment.
- Icelandic soils, particularly Andosols, have unique properties influencing radionuclide retention.
Purpose of the Study:
- To investigate the retention and vertical distribution of 137Cs in various Icelandic Andosols.
- To correlate 137Cs levels with environmental factors like precipitation.
- To assess the impact of soil properties and environmental conditions on radiocaesium mobility.
Main Methods:
- Soil sampling at 29 sites across Iceland at depths of 0-5, 5-10, and 10-15 cm.
- Measurement of 137Cs concentrations in soil samples.
- Correlation analysis between 137Cs levels, precipitation, and soil characteristics.
Main Results:
- 137Cs concentrations varied significantly (300–4800 Bq m⁻²), closely correlating with total annual precipitation (r²=0.71).
- An average of 82.7% of 137Cs was retained in the uppermost 5 cm of soil.
- Even coarse-grained Vitrisols with low clay and organic matter content retained 74% of 137Cs in the top 5 cm.
Conclusions:
- Icelandic Andosols, due to colloidal materials like allophane and ferrihydrite, strongly retain 137Cs.
- Despite harsh environmental conditions (freezing, waterlogging), vertical migration of 137Cs is negligible in these soils.
- Soil erosion and aeolian processes are identified as key factors influencing 137Cs distribution.