METAL CONTAMINATION OF SEDIMENTS IN THE NORTH RIVER ESTUARY, SALEM, MA

The North River and its estuary in Salem, MA is an important body of water for industrial and recreational use. For many decades, industrial wastes were emptied directly into the North River. Much of the waste was related to the many tanneries that lined the North River in Peabody and Salem, MA. Many of these waste products contain toxic elements such as As and Cr. The metals within the industrial wastes are often incorporated into the sediments near the mouth of the river. The distribution of metals within the North River sediments was determined using a portable x-ray fluorescent spectrometer. The full range of metals measured in this study include As, Cd, Cr, Cu, Pb, Hg, Ni, Ag, and Zn. Results indicate substantially elevated trace metal concentrations in all samples throughout the river and estuary. In particular, Cr, Hg, and Pb are consistently at concentrations above the Effects Range Medium while Cu, Zn and As are consistently above the Effects Range Low values. Effects Range Medium and Effects Range Low indicate probable harm to 50 percent and 10 percent of the biological population within the sediments respectively.

When plotted against the Fe concentration, Pb, Cu, Hg, and Zn display a positive correlation while Cr and As show no correlation to Fe at all suggesting a difference in the origin and geochemical behavior of Cr and As compared to the other metals. Comparison of the data in the North River and its estuary to data collected in the nearby Forest River estuary display differences that most likely reflect the varied industrial histories of each area. For example, although both sites show elevated concentrations of Pb, there is no correlation of Pb with Fe at Forest River, suggesting a different source of Pb in each location. The samples have been expanded to include additional parts of the North River estuary as well as the upstream portion of the river itself. Grain size analysis is being conducted on the samples to check for the expected association of the metals with the fine fractions of the sediment. Loss on ignition is also being conducted to check for a correlation with organic carbon content.