Lithium Isotope Fingerprints in Coal and Coal Combustion Residuals from the United States

Jennifer S Harkness (1) , Laura S Ruhl (2) , Romain Millot (3) , Wolfram Kloppmann (3) , James C Hower (4) , Helen Hsu-Kim (1) , Avner Vengosh (1)

1 Duke University [Durham]
2 University of Arkansas at Little Rock
3 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
4 UK - University of Kentucky

Coal is a major energy source worldwide and is a large fraction of the total energy production in the US. The disposal of coal combustion residuals (CCRs) into landfills and surface impoundments present an environmental challenge given the high levels of toxic metals in CCRs that are highly mobile into the aquatic phase. Here we present the lithium isotope composition of coals and CCRs originated from several U.S. basins. δ 7 Li values in CCR leachates from the Appalachian Basin, the Illinois Basin and the Powder River Basin vary from-7‰ to +12.8‰, with an average of ±1.6±5.0‰. CCR's from the Powder River Basin had a higher δ 7 Li of 7.6±5.4‰ compared to the Appalachian and Illinois Basins (+0.3±6.6‰ and-0.1±1.3‰, respectively). Effluents from six coal ash ponds in North Carolina show a similar range in lithium isotopes (δ 7 Li =-6.2 to +8.7‰) suggesting limited lithium isotope fractionation during storage in surface impoundment. We show that lithium isotopes, particularly when coupled with boron isotopes, could distinguish CCR contaminants from oil and gas wastewater, including conventional produced waters and hydraulic fracturing fluids.

Keywords: lithium; coal; CCRs; tracers

Domains: Earth Sciences

Jennifer S Harkness, Laura S Ruhl, Romain Millot, Wolfram Kloppmann, James C Hower, et al.. Lithium Isotope Fingerprints in Coal and Coal Combustion Residuals from the United States. Procedia Earth and Planetary Science, 2015, 13, pp.134 - 137. ⟨10.1016/j.proeps.2015.07.032⟩. ⟨hal-03699877⟩