COPPER AND ZINC CONTAMINATION IN CONNECTICUT HARBOR SEDIMENT

Harbor sediments, due to restricted water circulation and the proximity to multiple sources of industrial and municipal wastewater, are often contaminated with metals of environmental concern. Sediment metal contents also vary as a function of sediment type and coastal harbors are usually characterized by a variety of sedimentary environments. Since 2001, SCSU Center for Coastal and Marine Studies researchers have collected and analyzed the composition of surface sediments from eight Connecticut harbor and river estuaries with the specific goal of conducting a high spatial resolution sampling within each harbor to determine variations in sediment composition and metal contamination. Harbors examined in this study represent a range of demographics, land use, urbanization and industrialization, and are geographically located in eastern LIS [New London and Clinton], central LIS [Branford, New Haven and Milford] and western LIS [Housatonic river estuary, Bridgeport and Norwalk]. All median and mean copper (Cu) and zinc (Zn) concentrations exceed their respective crustal abundance values. For many harbors, crustal abundance of Cu is exceeded by greater than 10-20 fold while Zn enrichment relative to background is 2-4 fold. Embayment sediment Cu and Zn also show a greater range of variability compared to their respective location in greater LIS. Linear regression analyses of the sediment Cu and Zn concentrations within each harbor show that Cu and Zn co-vary in CT river and harbor sediment. Variations in sediment Cu and Zn are largely explained by variations in sediment physical properties. Copper is strongly correlated with both sediment loss on ignition (LOI) and sediment Fe for all harbors studied. Locations within each of the harbor/river estuaries identified as “hot spots” are characterized by the presence of fine-grained, high LOI sediment and are most frequently located in the inner (northern) reaches of the harbors (dredged channels, river mouths, river coves) proximate to contaminant sources. Copper and Zn sediment concentrations at these “hot spot” locations in all CT harbors examined exceed ERL and ERM thresholds. Additionally, two WLIS harbors (Housatonic river estuary and Bridgeport) are characterized by disproportionately high sediment Cu concentrations compared to other CLIS and ELIS harbors.