MERCURY CONTAMINATION IN CONNECTICUT RIVER SEDIMENTS

The Connecticut River is a tributary of Long Island Sound containing elevated sediment mercury levels from many sources; these include historical contamination from the industrial period of the 1800's as well as current atmospheric deposition. For this project we have taken sediment cores in a series of inlets connected to the river from near the Sound to Mt. Tom, a large coal-burning power plant in central Massachusetts. Cores were analyzed for TOC, grain size distribution, porosity and lead-210 concentrations. While background mercury concentration for this area was approximately 40-80ppb in the pre-industrial period, preliminary analyses of sediment cores have concentrations reaching nearly 1000 ppb, with common values between 200 and 500 ppb. As expected, TOC values closely track changes in Hg concentration, since much of the Hg is adsorbed into organic matter. Sediment samples are being digested for other trace metal determinations to further aid in source identification of the Hg. The sedimentology of the cored locations is also being studied using GPR and sonar to help place the history of Hg loading in the context of sediment transport to these depositional sites.