TRACE ELEMENTS IN DAN RIVER SEDIMENT AFTER THE 2014 COAL ASH SPILL

On February 2, 2014, an estimated 82,000 tons of coal ash and 27 million gallons of contaminated water were released into the Dan River from a ruptured storm drainage pipe underneath the ash pond at the Duke Energy Steam Station in Eden, NC. Coal ash contains elevated concentrations of trace elements, some of which are toxic, prompting a concern that the ash spill could adversely impact human, aquatic, and environmental health over time.

The objective of this study was to identify coal ash derived trace element signatures in the river sediment over space and time. Sediment samples were collected by our research group and the Virginia Department of Environmental Quality over a two year period. The samples were digested and analyzed for trace elements using ICP-MS. We used correlation analysis to examine patterns and potential relationships in the geochemical data. Results illustrated strong positive correlations of several trace elements, including As, Cd, Cr and Pb, with Fe. These correlations suggest a geochemical association, likely adsorption, of these elements on Fe-bearing minerals or mineral coatings. In addition, we examined data for outliers as potential indicators of coal ash inclusion in sediment. For example, although As showed a strong positive correlation with Fe along one linear trend, there were 7-8 samples that were enriched with As with respect to Fe, suggesting a coal ash concentration in those sediment samples. We also compared the trace element concentrations in sediments to sediment quality guidelines. Further statistical analysis will be conducted to yield additional information on trace element distribution in the Dan River resulting from the coal ash spill.