OCCURRENCE AND DISTRIBUTION OF TRACE-METAL-CONTAMINATED SEDIMENTS IN THE ASHUELOT RIVER, KEENE, NH

Given the history and geography of the Ashuelot River in southwestern New Hampshire, we have been assessing the concentrations of toxic trace elements (As, Pb, Cu, Ni, Cr, and Zn) in sediments from the river. Lead, Copper, and Nickel were all found at relatively high total concentrations in bulk sediment—exceeding toxicological thresholds (Buchman, 1999), in some cases significantly—at one or more sampling sites within the city of Keene. Following initial reconnaissance "grab" sampling, we have mapped out the extent and distribution of contamination at two selected sites. This work suggest that the occurrence of contaminated sediments is wide-spread, but we do not as yet understand the pattern of distribution in relationship to the pattern of stream flow and sediment transport in this meandering river system. For example, the highest Lead concentrations are found on the outsides of the river bends, while sediment deposition would be expected to occur on the insides of the river bends. Additional work has also been done to assess how labile these metals are within the sediments.