BORON AND STRONTIUM ISOTOPE PROXIES FOR TRACING THE ENVIRONMENTAL IMPACT OF THE TVA COAL ASH SPILL, KINGSTON, TN

An investigation of the environmental impact of the largest coal ash spill in US history at the Tennessee Valley Authority (TVA) Kingston coal-burning power plant has revealed that leaching of the coal combustion products (CCP) caused contamination of surface waters in areas of restricted water exchange, but only trace levels were found in the downstream Emory and Clinch Rivers due to river dilution (Ruhl et al.; ES&T, August 2009). Among the distribution of leachable coal ash contaminants (LCAC), boron and strontium are conspicuously high. Leaching experiments performed on the TVA ash has also shown high boron (14.8 ppm) and Sr (84.8 ppm) concentrations. Here we report preliminary results of the boron and strontium isotope compositions of the LCAC derived from the TVA ash.  The d¹¹B values of surface water associated with the coal ash spill in Kingston and laboratory- leaching experiments are - 12‰ and -16‰ (relative to NIST951), respectively. The ⁸⁷Sr/⁸⁶Sr ratio of LCAC derived from the TVA ash is 0.711329. The boron isotope signature of the LCAC is significantly different from that of common boron in aquatic systems (a d¹¹B range of 0 to +30‰) and other boron sources (waste water; 0 to +10‰). The combined distinguished B isotope and Sr isotope compositions of the LCAC provide a novel geochemical tool for quantifying the CCP impact on the environment.