The percentage of CCP plus coal particles in the sand size fraction, with the remainder of the sample being composed predominately of quartz and a trace of muscovite and feldspar, is plotted in Fig. 6. Samples between

242 and 440 cmblf contain high selleck products amounts of CCP and coal (Fig. 6). The basal lithologic unit contains gravel-sized sandstone and shale similar to the rocks of the Cuyahoga Group, rounded quartz pebbles similar to those found in the Sharon Formation, and particles of coal. ESEM-EDAX examination of grains that were magnetically extracted from the CCP-bearing sediment reveals spherical particles having Fe, O, Al and Si compositions and surface textures characteristic of CCP (Rose, 1996). In core C4, trace metal concentration profiles of Zn, Cr, Cu, and Pb all show similar trends, and the Pb profile is plotted in Fig. 6. Trace metal concentrations are low but steadily increase in concentration from 0 to 200 cmblf. Between 200 and 520 cmblf the trace metal concentrations are high but variable, and then decrease from 520 cmblf to the base of the core. Samples having a sand component generally have lower trace metal content, because metals are preferentially absorbed to

finer particles (Fig. 6). However, mud is the dominate lithology throughout this website the core; thus, the major changes in metal content are not controlled by changes in grain size. The consensus-based probable effect concentration (PEC) is the freshwater sediment contaminant concentration above which adverse biologic effects are expected to frequently occur in sediment-dwelling organisms (MacDonald et al., 2000). Pb, Cr, and Zn display similar profiles with concentrations exceeding the PEC between about 125 and 520 cmblf (Fig. 6). Cu exceeds the PEC between about 240 and 475 cmblf. Upstream of the former power plant the impoundment continues to narrow and shallow in an upstream direction (Fig. 2). Between cross sections 11 and 15 the water area decreases from 320 m2 to 190 m2 (Fig. 5). However, field observations indicated that flow velocity remains low in this reach. Core C10 reached the underlying

bedrock and recovered 570 cm of sediment. cAMP Core C11 recovered 520 of sediment before sampling was halted due to lightning. These two cores have low magnetic concentration (Fig. 4). The dominant lithology is dark brown to black mud interbedded with layers of organic matter and sand. CCP-bearing sediment layers are absent. The sandy layers correspond to increased magnetic susceptibility values (Fig. 4). Upstream of cross section 16 the water area decreases from 100 to 30 m2, and flow velocity was observed to increase dramatically. Both cores C8 and C9 ended at bedrock and recovered approximately equal amounts of dark brown mud and gravelly sand. The higher magnetic susceptibility values correspond to the gravelly sand layers (Fig. 4). The 210Pb concentration generally declines with depth in core C4 (Fig. 7). The background (i.e., supported) 210Pb concentration is the average (0.