Magnetic susceptibility measurements to detect coal fly ash from the Kingston Tennessee spill in Watts Bar Reservoir

An estimated 229 000 m(3) of coal fly ash remains in the river system after dredging to clean-up the 2008 Tennessee Valley Authority (TVA) spill in Kingston, Tennessee. The ash is heterogeneous with clear, orange and black spheres and non-spherical amorphous particles. Combustion produces iron oxides that allow low field magnetic susceptibility (chi(LF)) and percent frequency dependent susceptibility (chi(FD)%) to be used to discriminate between coal fly ash and sediments native to the watershed. Riverbed samples with chi(LF) greater than 3.0 x 10(-6) m(3)/kg, have greater than 15% ash measured by optical point counting. chi(LF) is positively correlated with total ash, allowing ash detection in riverbed sediments and at depth in cores. The ratio of ash sphere composition is altered by river transport introducing variability in chi(LF). Measurement of chi(LF) is inexpensive, non-destructive, and a reliable analytical tool for monitoring the fate of coal ash in this fluvial environment. (c) 2012 Elsevier Ltd. All rights reserved.