Heavy metal bioaccumulation in vegetation and small mammals inhabiting a coal ash disposal site

Coal ash is exempted from treatment as a hazardous waste under RCRA Subtitle C. The US Environmental Protection Agency justifies this exemption contending that coal ash does not possess any of the four RCRA hazardous properties (ignitability, corrosivity, reactivity, or toxicity). However, metals in coal ash may accumulate to toxic levels in biota on ash disposal sites. From 1955 to 1989, the Department of Energy`s Oak Ridge Y-12 Plant sluiced coal ash to a 36-ha earthen retention basin (Filled Coal Ash Pond; FCAP); the basin drains to a small local stream. The FCAP is now revegetated, and a productive terrestrial ecosystem now exists on the site. Vegetation and small mammals were collected from the FCAP and a nearby reference site in September 1992, and June--September 1993. Vegetation and small mammals were analyzed for As, Cd, Cr, Pb, Se, Tl and Hg. Mean concentrations of Se and As for FCAP vs. reference site samples were significantly higher in deciduous tree foliage (18.9 {+-} 19.1 /{mu}g Se/g and 1.6 {+-} 0.69 /{mu}g As/g) and small mammals (2.4 {+-} 1.4 {mu}g Se/g and 0.16 {+-} 0.1 {mu}g As/g) inhabiting the FCAP. Thus, biota living on or near the ash disposal site have bioaccumulatedmore » Se and As. Concentrations of these metals in vegetation and small mammals are sufficient to cause toxic effects in their consumers.« less