The distribution and enrichment of naturally occurring radioactive materials (NORM) in coal combustion residuals (CCRs) from different coal source basins have not been fully characterized in the United States. Here we provide a systematic analysis of the occurrence of NORM (232Th, 228Ra, 238U, 226Ra, and 210Pb) in coals and associated CCRs from the Illinois, Appalachian, and Powder River Basins. Illinois CCRs had the highest total Ra (228Ra + 226Ra = 297 ± 46 Bq/kg) and the lowest 228Ra/226Ra activity ratio (0.31 ± 0.09), followed by Appalachian CCRs (283 ± 34 Bq/kg; 0.67 ± 0.09), and Powder River CCRs (213 ± 21 Bq/kg; 0.79 ± 0.10). Total Ra and 228Ra/226Ra variations in CCRs correspond to the U and Th concentrations and ash contents of their feed coals, and we show that these relationships can be used to predict total NORM concentrations in CCRs. We observed differential NORM volatility during combustion that results in 210Pb enrichment and 210Pb/226Ra ratios greater than 1 in most fly-ash samples. Overall, total NORM activities in CCRs are 7-10- and 3-5-fold higher than NORM activities in parent coals and average U.S. soil, respectively. This study lays the groundwork for future research related to the environmental and human health implications of CCR disposal and accidental release to the environment in the context of this elevated radioactivity.
|Number of pages||7|
|Journal||Environmental Science and Technology|
|State||Published - Sep 15 2015|
Bibliographical notePublisher Copyright:
© 2015 American Chemical Society.
ASJC Scopus subject areas
- Chemistry (all)
- Environmental Chemistry