DISTRIBUTION OF TRACE METALS IN THE SEDIMENTS FROM THE WINTERGREEN BROOK DRAINAGE BASIN, HAMDEN, CT

Wintergreen Brook lies directly adjacent to one of the earliest areas of industrialization in the United States yet its watershed has remained relatively undeveloped providing a unique opportunity to study non-point source deposition of trace metals. The western edge of the drainage basin is flanked by West Rock Ridge (elevation 200 m) and much of the watershed lies 75-200 meters above the surrounding heavily urbanized region that includes the cities of New Haven and Hamden. Land use within the drainage basin is primarily forestland, agriculture (orchards and farms), and suburban housing. The bedrock in the basin includes Mesozoic arkosic sandstones/siltstones, and diabase that are overlain, in some areas, by late Cenozoic glacial deposits. The watershed includes a number of lakes/ponds, the largest of which is Lake Wintergreen. This 45-acre impoundment served as a water supply reservoir for the New Haven metropolitan area between 1863 and 1978. Wintergreen Brook forms a tributary of the West River that flows into New Haven Harbor/Long Island Sound. The harbor and Long Island Sound have well documented histories of anthropogenic metal accumulation. Surface sediments have been collected from streams and lakes throughout the Wintergreen Brook watershed and cores have been collected from a select number of lakes. Sediment samples have been analyzed by energy dispersive XRF for a range of environmentally sensitive trace elements including Cr, Ni, Cu, Zn, As, Cd, Sn, Ba, and Pb. The samples show significant enrichments in some metals relative to concentrations observed in pre-industrially deposited sediments. The enrichment is attributed to non-point source accumulation, primarily atmospheric in origin.