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Cesium-137 in Montana soils
O Arnalds1, N H Cutshall, G A Nielsen
1Plant and Soil Science Department, Montana State University, Bozeman 59717.
Health Physics
|December 1, 1989
Summary
Cesium-137 (137Cs) fallout in Montana soils is primarily in the top 10 cm. Higher concentrations correlate with annual precipitation, with deeper soil contamination due to animal activity and water flow.
Area of Science:
- Environmental Science
- Radiological Science
- Soil Science
Background:
- Cesium-137 (137Cs) is a significant artificial radionuclide resulting from nuclear fallout.
- Understanding its distribution in terrestrial ecosystems is crucial for environmental monitoring and risk assessment.
Purpose of the Study:
- To quantify 137Cs fallout levels in Montana soils.
- To investigate the vertical distribution and factors influencing 137Cs concentration in soil.
Main Methods:
- Soil samples were collected from 11 diverse sites across Montana.
- Gamma spectrometry was used to measure 137Cs concentrations (mBq g-1 and mBq cm-2).
- Vertical distribution was analyzed by examining samples at different depths.
Main Results:
- Near-surface soil 137Cs concentrations ranged from 20-200 mBq g-1.
- The majority of 137Cs was found in the top 10 cm of soil.
- Areal concentrations (130-748 mBq cm-2) showed a strong positive correlation with annual precipitation.
Conclusions:
- Montana soils exhibit variable 137Cs fallout levels, influenced by precipitation.
- Animal disturbances and water-mediated sediment transport contribute to deeper 137Cs penetration in soil.
- Precipitation is a key factor controlling the areal distribution of fallout 137Cs in the region.