SOIL-SOIL SOLUTION DISTRIBUTION COEFFICIENT OF RADIOIODINE IN SURFACE SOILS AROUND SPENT NUCLEAR FUEL REPROCESSING...

Area of Science:

• Environmental Chemistry
• Soil Science
• Radiochemistry

Background:

• Radioiodine contamination in soil poses environmental risks.
• Understanding radioiodine's soil sorption behavior is crucial for remediation.
• Soil organic matter significantly influences contaminant mobility.

Purpose of the Study:

• To investigate the soil-solution distribution coefficient (Kd) of radioiodine (125I).
• To determine the role of total carbon (TC) and dissolved organic carbon (DOC) in radioiodine sorption.
• To elucidate the mechanisms of radioiodine binding in soils with varying organic matter content.

Main Methods:

• Batch sorption experiments using 125I tracer.
• Analysis of radioiodine distribution in soils with diverse total carbon (TC) levels.
• Correlation analysis between Kd-125I, TC, and dissolved organic carbon (DOC).
• Size fractionation of 125I in the liquid phase.

Main Results:

• Positive correlation between Kd-125I and TC in low-TC soils (<10g kg-1).
• Negative correlation between Kd-125I and DOC in high-TC soils (>10 g kg-1).
• 125I preferentially binds to high-molecular-weight organic matter in DOC-rich soils.
• Anion exchange capacity of soil organic matter (SOM) is key in low-SOM soils.

Conclusions:

• Radioiodine sorption is governed by DOC in high-SOM soils.
• In low-SOM soils, radioiodine sorption is primarily controlled by SOM's anion exchange capacity.
• The findings provide insights into radioiodine fate and transport in different soil environments.