²¹⁰Po sequential extraction applied to wetland soils at uranium mining sites

Area of Science:

• Environmental Science
• Radiochemistry
• Geochemistry

Background:

• Uranium mining disrupts natural radionuclide equilibrium.
• Naturally occurring radionuclides, including those in the 238U decay series, are present in soils.
• Polonium-210 (210Po) is the final radionuclide in the 238U decay series.

Purpose of the Study:

• To quantify the long-term effects of uranium mining on 210Po behavior in soils.
• To determine the distribution of 210Po across different soil fractions.

Main Methods:

• Soil samples were collected from two French uranium mining sites (quarried and natural).
• The distribution of 210Po was analyzed across various soil fractions: water soluble, exchangeable, bound to carbonates, bound to iron/manganese oxides, bound to organic matter, and residual.

Main Results:

• Polonium-210 was predominantly found in the residual soil fraction (87-90%) at both study sites.
• A smaller proportion of 210Po was associated with the carbonate fraction (5-9%).
• Activity of 210Po in other soil fractions was negligible compared to the total activity.

Conclusions:

• Former uranium mining activities significantly influence the distribution of 210Po in soils.
• The residual fraction is the primary sink for 210Po in uranium-affected soils.
• Understanding 210Po partitioning is crucial for assessing the long-term environmental impact of uranium mining.