Distribution and Leaching Behavior of Trace Elements and Radionuclide in Waste Rocks of a Uranium Mine: Implications for Environmental Risk Assessment and Mitigation

The distribution pattern of trace elements in waste rocks of a uranium mine in the Singhhum region, India, and their leaching behavior in the presence of natural and anthropogenic leaching agents were evaluated in the study. Tessier’s Sequential extraction revealed that heavy elements that largely exist in residual and reducible phases are stable; those in exchangeable fractions pose a higher risk due to their mobility. More than half of the cobalt (54.0–79.9%), copper (70.7–91.9%), iron (85–94%), manganese (50–75%), and nickel (61.3–90.4%) were present in the residual phase. The mobility factor was found to decrease with increasing particle size for most elements, suggesting lower leaching potential for larger particles. The leaching potential studies with rainwater showed that ionic concentrations decreased with increasing liquid-to-solid ratios from 0.5 to 10, indicating a dilution effect. The gamma spectrometric analysis of waste rocks showed that 226Ra with the highest (948 ± 16–2145 ± 30 Bqkg−1) and 232Th with the lowest (72 ± 2–132 ± 9 Bqkg−1) activity levels among the measured radionuclides. The study will help to assess the environmental risks and develop effective long-term mitigation strategies to prevent contamination of soil, water, and air. The findings also provide critical input for environmental risk assessment frameworks and guide mitigation approaches such as selective waste segregation and controlled reuse of mine waste rocks.