METAL CONTAMINATION OF SEDIMENTS IN THE ASHUELOT RIVER, KEENE, N.H

Over the years my students and I have sampled sediments from the Ashuelot River in Keene, New Hampshire, to assess heavy metal contamination (Cr, Ni, Cu, Zn, and Pb). We have discovered very high levels of lead in sediments underneath bridges that had been painted with lead paint. In our current work, the lead-contaminated sediments do not appear to be very mobile in the river, as the lead concentration in the sediment drops off rapidly as one moves downstream from the bridges, however the concentrations are still in excess of background values. Some of the other metals are also found at elevated concentrations under the bridges, and may also be attributed to paint pigments. However, we have also observed elevated concentrations of Cr, Ni, Cu, and Zn (but not Pb) in sediments not associated with the bridges. These occurrences are consistent with Road Dust Sediment contamination that we have measured in soils adjacent to a nearby highway, and appear to be associated with parking-lot runoff and a storm drain outfall into the river.