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Radionuclide mobility and bioavailability in Norwegian and Soviet soils
D H Oughton1, B Salbu, G Riise
1Isotope and Electron Microscopy Laboratories, Agricultural University of Norway, Aas.
The Analyst
|March 1, 1992
Summary
Chernobyl radionuclides cesium-137 (137Cs) and strontium-90 (90Sr) speciation in soils shows 137Cs is strongly bound, while 90Sr is more mobile. Fallout speciation, not local factors, explains differing radionuclide distribution.
Area of Science:
- Environmental Science
- Radiochemistry
- Soil Science
Background:
- Chernobyl-derived radionuclides, specifically cesium-137 (137Cs) and strontium-90 (90Sr), pose long-term environmental risks.
- Understanding radionuclide speciation in soils is crucial for assessing their mobility and bioavailability.
Purpose of the Study:
- To investigate the chemical speciation of 137Cs and 90Sr in soils from Norway, Byelorussia, and the Chernobyl region.
- To determine the influence of fallout characteristics versus local environmental factors on radionuclide distribution.
Main Methods:
- Sequential extraction procedure applied to soil samples.
- Analysis of radionuclide (137Cs, 90Sr) and stable element (Cs, Sr) distribution in different soil fractions.
Main Results:
- Most 137Cs (>80%) was strongly associated with soil components, indicating low mobility.
- Up to 70% of 90Sr was found in easily extractable fractions, suggesting higher mobility.
- The 90Sr:137Cs ratio decreased with distance from the Chernobyl reactor.
- Easily extractable 90Sr fractions were lower in Chernobyl-area soils compared to other sites.
- Distribution of stable Cs and Sr mirrored radionuclide distribution, suggesting similar chemical behavior.
Conclusions:
- Radionuclide speciation in fallout, particularly the presence of hot particles near the reactor, significantly influences 90Sr and 137Cs distribution.
- Location-specific differences in radionuclide distribution are primarily attributed to initial fallout speciation, not local soil environmental factors.