CHLORINATED HYDROCARBONS AND RADIONUCLIDE CHRONOLOGIES IN SEDIMENTS OF THE HUDSON RIVER AND ESTUARY, NEW-YORK

The Hudson River received discharges of at least several hundred tons of PCB [polychlorinated biphenyl] from 2 General Electric capacitor manufacturing facilities in the upper part of the drainage basin .apprx. 1950-1976. Measurements of PCB compositions and amounts in sediment cores throughout the tidal Hudson (.apprx. 250 km) indicated that maximum concentrations occurred in the early 1970s, probably due to removal of a dam just downstream of the release area in 1973. Significant decreases in surface sediment PCB concentrations occurred since .apprx. 1973, well before monitored releases of PCB from the manufacturing facilities ceased in 1976, probably primarily as the result of dilution and burial of the most highly contaminated sediments released upon removal of the dam with soils from the drainage basin. Declines in the concentrations of chlorinated hydrocarbon pesticides and fallout radionuclides since the mid-1960s and reactor-released radionuclides over 1971-1975 were also established from sediment core measurements.